Corresponding author: Nico Fassbender (
Academic editor: Danwei Huang
During the 2019 First Descent: Seychelles Expedition, shallow and deep reef ecosystems of the Seychelles Outer Islands were studied by deploying a variety of underwater technologies to survey their benthic flora and fauna. Submersibles, remotely operated vehicles (ROVs) and SCUBA diving teams used stereo-video camera systems to record benthic communities during transect surveys conducted at 10 m, 30 m, 60 m, 120 m, 250 m and 350 m depths. In total, ~ 45 h of video footage was collected during benthic transect surveys, which was subsequently processed using annotation software in order to assess reef biodiversity and community composition. Here, we present a photographic guide for the visual identification of the marine macrophytes, corals, sponges and other common invertebrates that inhabit Seychelles’ reefs. It is hoped that the resulting guide will aid marine biologists, conservationists, managers, divers and naturalists with the coarse identification of organisms as seen in underwater footage or live in the field.
A total of 184 morphotypes (= morphologically similar individuals) were identified belonging to
Coral reef ecosystems are some of the most diverse hotspots for life on our planet. Both shallow and deep water coral reefs are valued for their incredible diversity and species richness, yet little is known about the processes and functions of mesophotic coral ecosystems (MCEs; reefs ~ 30–150 m depth, as proposed by
Deeper coral ecosystems provide a number of ecosystem services to support their shallow-water (< 30 m depth) counterparts and oceanic processes, harbouring unique assemblages of life and preserving biodiversity by supporting shallow reef systems (
To effectively protect and manage an ecosystem, it also needs to be documented and monitored. Knowledge of mesophotic and rariphotic reefscapes in Seychelles waters remains poorly known. Gaining a better understanding of deeper reef ecosystems and their communities was identified as a crucial step towards effectively protecting 30% of Seychelles’ waters as part of the
The Seychelles consists of 115 islands located in the Western Indian Ocean, between 480 to 1600 km from the African coast (Fig.
The multidisciplinary First Descent: Seychelles Expedition, from which images in this guide were drawn, provided an opportunity to understand patterns of diversity and connectivity between the various shallow and deep reef marine ecosystems.
During the expedition, benthic and fish communities were surveyed across seven sites around Seychelles Outer Islands (Fig.
All of the collected video footage was screened during and straight after the expedition in order to create image-based morphotype lists. These, along with collected specimens, were then reviewed during a taxonomic workshop that took place in the South African Institute of Aquatic Biodiversity in August 2019 (
This guide is designed to aid with the identification of organisms as seen in underwater footage or in the field. For each entry, we provide a taxonomic identification and higher-order classification, information on distribution across our surveyed sites and observed depth ranges and sizes, based on our work only, a short morphological description as observed from the video footage and some representative images extracted from the video footage. Where available, an additional
Identifying taxa from images is challenging. Well-trained researchers use a combination of traditional taxonomic features and ecological information (e.g. depth, location, knowledge of the local species pool) to arrive at decisions on a taxon identification. The taxonomic level of each identification will vary depending on the type of organism in question, but in general, rarely reaches species level. This is due to a number of challenges, one of which being the often reduced quality of frames exported from video footage due to the camera moving fast or suspended sediment present within the frame. Additionally, some groups either have enormous morphological plasticity (e.g. sponges) or their unique characters are too small to be distinguished on video footage alone without the use of high-power microscopes (e.g. corals, algae). We have, therefore, placed each taxon into visually distinct morphotypes (i.e. aggregation of morphologically similar individuals) that can correspond to species or higher taxonomic level (genus, family etc.).
All observed morphotypes are divided into 18 major classification groups, ranging from phylum to order. The choice of the taxonomic level for each major group corresponds with groups commonly recognised by the general public and experts alike, such as hard corals (Order:
Wherever species-level identifications are not possible, organisms are provided with a higher classification ranking (e.g. genus, family, class) followed by the use of open nomenclature (ON) signs applicable to image-based faunal analyses (e.g. indet., stet., inc.) as suggested by
Finally, whenever
A green seaweed that grows in twig-like, branched plants with a creeping stolon and multiple erect fonds. The stolon is attached to the seabed by several bunches of rhizoids. Species of
A green seaweed with creeping stolon and erect fronds with branchlets consisting of a short pedicel ending in a rounded, disc-like to spherical appendage. Stolons are attached to the substratum by bunches of rhizoids. Species of
Seaweed whose thallus can display erect or prostrate forms, usually stiff. Erect forms (as observed here) display dichotomous branching, attached to the substratum by groups of rhizoids. The colour is dark green, sometimes with a brownish tint (Fig.
Conspicuous, cactus-like macroalgae with jointed, disc-like and calcified segments. Individual segments can vary in shape that ranges from round to kidney-, wedge- or even cylindrical-shaped. The thallus anchors to the bottom by a dense tuft of rhizoids which varies in shape depending on the substratum. Dead specimens have been observed to lose their green colour, revealing their white calcium carbonate skeletons. Five species were identified from collections (
A green calcified seaweed composed of a stipe and either a single or several fan-shaped blades. It is anchored to the bottom by uncalcified tufts of rhizoids, which vary in shape depending on the substratum, most commonly sand.
Thin, leaf-like green algae made of complanate, monostromatic, reticulate blades that occasionally form dense mats (Fig.
A green algae that forms somewhat encrusting, hollow or solid, globose or flattened thalli made of vesicular segments (pseudoparenchymatous cushion of polygonal cells). They are attached to the substratum by rhizoids produced by basal vesicles (Fig.
Thallus can vary in shape and resemble lettuce leaves. The thallus is composed of two layers of cells attached to the substratum by a holdfast made of rhizoidal proliferations. The overall shape of the algae is very variable depending on the environmental conditions. Colour varies from light to dark green (Fig.
Brown fan-shaped blade with a firm texture. The creeping, ascendant or erect fonds can range from foliose to rounded and are attached to the substratum by rhizoids. Previously thought to be represented by only one species (
Creeping red fleshy algae with small, arborescent and feather-like fonds arising from a decumbent rhizome-like base (Fig.
Commonly known as crustose coralline algae, these encrusting algae grow on rocks, coral fragments, shells, other algae or seagrasses. Hard and rock-like, their surface can be smooth or rough. Colours range from bright pink to purple. This group contains a variety of species that are difficult to identify from images, hence, no attempt was made to identify them at a lower taxonomic level (Fig.
This seagrass species can form dense meadows and is identified by its linear and falcate leaves arising from a rooted rhizome. Its colour is a rich green. One species (
Species of seagrass with a creeping bifurcated stem from which arise distichously arranged linear, oblong or rounded delicate leaves. Colour light green (Fig.
Oval oral disc that is flat or slightly undulating and densely covered with finger-like tentacles. Tentacles are hardly tapered or blunt, sometimes with a swollen end. Oral disc white; tentacles light brown to green. Typically found growing in comparably exposed positions. They can host anemonefish and are associated with the anemonefish species
Meandering oral disc; surface covered in small tentacles (~ 1-2 cm), sometimes longer (~ 5 cm). Dark brown colouration with whitish stripes throughout the colony. Hosts several species of anemonefish, associated with
Round oral disc (~ 4 cm in diameter) with numerous short tentacles (~ 1.5 cm) along the outer edge of the disc. Colour orange to reddish. Further microscopic examination is necessary for positive taxonomic identification (Fig.
Round oral disc (~ 2.5 cm in diameter) with numerous, thin (~ 2.5 cm long) tentacles along the outer edge of the disc. Colour translucent to white. Further microscopic examination is needed for positive taxonomic identification (Fig.
Round oral disc (7 cm in diameter) with numerous thin tentacles (~ 6 cm long) along the outer edge of the disc. Oral disc pale to bright orange, tentacles translucent to pale white. Further microscopic examination is needed for positive taxonomic identification (Fig.
Round oral disc entirely covered by thick, long (with respect to the size of the disc) tentacles. Colour of oral disc unknown; tentacles dark brown to dark red with white tips. Further microscopic examination is needed for positive taxonomic identification (Fig.
Colonies up to 1.7 m in height, mainly bushy and bramble-like, sparsely to densely-branched with fine, elongate branches. Light to dark brown colour (Fig.
Colonies observed were large (> 2 m in height), fan-shaped and uniplanar. With thick, central stalk and several finer branches. Colour dark red to orange (Fig.
Colonies up to 20 cm in height, columnar, monopodial or very sparsely branched. Thick bottlebrush-like appearance. Irregularly pinnulate. Brownish to grey colouration. Darker coloured central axis enclosed by bushy, lighter coloured branches and polyps (Fig.
Colonies up to 1.8 m in height, densely branched, appearing rather bushy. Colouration ranges from brownish to grey and orange, with polyps coloured lighter than the branches (Fig.
Colonies have two rows of fine and long branches on either side of the central axis and grow up to ~ 15–20 cm in height. Branches are thin and rounded, giving the colony a feather-like appearance. Colonies are pink to purple coloured (Fig.
Colonies up to 50 cm in height, columnar, monopodial or very sparsely branched. Thin bottlebrush-like appearance. Irregularly pinnulate. Whitish to pink colouration. Darker coloured central axis enclosed by bushy, lighter coloured branches and polyps. Appears similar to
Colonies up to 1 m in height, fan-shaped and uniplanar with a high degree of ‘anastomosis’ (branch joins), giving the colonies a net-like appearance. In larger colonies, smaller branches may grow perpendicular to the main plane. Colour bright green to yellow. Occasionally with crinoid commensals (Fig.
Colonies thickly encrusted with lobed projections, typically < 50 cm across (= in the longest dimension). Some species are bowl-shaped or stand more erect. Generally following the substrate, colonies look like large plates. Some form small individual bumps (1), others have long valleys and walls (2). Polyps are only present on the upper surface. Colouration brown to grey. The tips of the individual lobes are often coloured lighter than the sides. Similar species include
Colonies are digitiform, with a short tapered stalk resembling a carrot, up to 10 cm long. Polyps are only extended at night. Colouration yellow, orange or red, with white polyps (Fig.
Colonies are lobate with conspicuous bare stalks merging into a wide, fleshy, disc-like head (polypary). The polypary is concave at the centre and wavy around the edges, giving it a mushroom appearance (especially in juveniles). Polyps are only found on top of the polypary. Colouration shades of brown, beige, yellow or green. Polyps are generally of the same colour as the colonies, but can be yellow or white in brown individuals. In downward facing videos typical for benthic surveys, the stalk will not always be visible. Maximum recorded size: 20 cm across. Similar species include
Colonies were up to 40 cm in height (Fig.
Colonies are small (< 25 cm in height) and growing as stubby, finger-shaped branches. No central stalk was visible on the captured footage. Surface covered with polyps giving it a fuzzy appearance. Colony colour was orange with orange polyps (Fig.
Individuals are whip-like, forming single, unbranched colonies growing up to 2 m in height. Distal parts can be straight, heavily bent or coiled. Colour ranges from red to orange, pink, white, orange-yellow with red polyps or red with white polyps. Individuals most likely belong to the genus
Colonies with sparse or rich dichotomous branching - in this survey, the sparsely branched form, seen in Fig. 35 below, was more common. Colonies can appear bushy to planar. The maximum recorded colony size was 50 cm in height. Branches are thick and relatively short and split into smaller branches towards the periphery of the colony. Colouration is red to orange.
Colonies up to 2 m in height, bush-like, with whip-like branches; branching can range from sparse to densely packed. Colouration is red to orange, pink, white, orange-yellow with red or white polyps. Similar-looking species include
Colonies up to 1.5 m in height, fan-shaped, with sparse, fine branches typically growing in one plane. Colonies sometimes show dichotomous branching and never show anastomoses. Branching starts from the bottom, hence, the stalk is rarely visible. Colour white with dark-brown to black coloured polyps (Fig.
Large sea fans (~ 1 m in height and width), with dense, uniplanar branches that create a mesh-like appearance; conspicuous central stalk. Colouration observed here was exclusively purple; however red, orange, yellow and shades of brown are also common. More sparsely branched colonies can resemble
Colonies typically < 1 m across, appear bushy, with either sparse, whip-like branches or dense shrub-like branches that have a smooth surface and blunt tips. Light brown to greyish colour (Fig.
Colonies up to 40 cm in height, can appear fan or bush-like, with thick branches covered in fuzzy-looking polyps. Colour ranges from yellow to green or brownish (Fig.
Colonies up to 20 cm in height, mostly fan-shaped and uniplanar, sometimes slightly bushy. Mostly dichotomously branched, where branches originate from the nodes. Colouration rich purple-reddish colour at the base that becomes lighter towards the tips of the branches. The centre of the colony always appears darker than the edges (Fig.
Colonies up to 60 cm in height, mostly fan-shaped, multiplanar with irregular branching. The periphery of the colony is rather sinuous. The main stem has a distinct orange colour with additional branches becoming successively lighter; tips of the branches appear almost white (Fig.
Colonies less than 20 cm in height, arborescent with dichotomous branching; sometimes appear slightly bushy when heavily branched. Colour deep purple with slightly lighter polyps (Fig.
Bushy colonies up to 20 cm in height, with close, short branching and distinct, large, round polyp bunches at the end of each branch. Colonies can show one of three growth forms: divaricate (sparse, arborescent branching with bundled polyps), glomerate (close, short branching with polyps forming rounded bunches) or umbellate (polyps forming umbrella-like crowns that may combine to form hemispheres). White stalk with polyps of red, orange, purple, yellow, pink or white colour (Fig.
Colonies umbellate up to 20 cm in height, with polyp bunches closely arranged at the same level on the end of small branches (twigs), forming umbrella-like crowns. Creamy-white colour (Fig.
Colonies are tree-like with branched polyparium, growing out from one single stem, growing up to 55 cm in height. Polyps are non-retractile and clustered at the end of the terminal branches, forming catkins. Colouration orange to yellow, cream, brown or purple.
Colonies up to 25 cm in height, sparsely branched and arborescent, often planar. Polyps only on the branched part of the colony and are normally expanded at night and in strong currents. Colouration translucent-white with bluish-purple polyps. Can be confused with
Colonies up to 50 cm in height, typically heavily branched with a bushy appearance. Colouration orange-brown with similar coloured polyps (Fig.
Colonies fan-shaped, mostly uniplanar, with a thick main stem and several thinner branches. Overall, there is a strong tree-like resemblance with branches growing upwards. Anastomoses are never observed. Colony size typically < 50 cm in height but can occasionally reach > 1 m. The colour is bright green to yellow. Young colonies grow upright into branched stalks and do not yet have a fan morphology. Belongs to either
Colonies large (typically > 1 m in height), slightly bushy, with dichotomous to pinnate branching. Branches covered with small polyps and appear fuzzy. Colour shades of brown to greenish-grey (Fig.
Colonies up to 30 cm in height, uniplanar, branching dichotomously from the bottom of the colony with no clear mainstem visible. Conspicuously monodirectional upward branching pattern. Branches covered in small polyps and appear fuzzy. Dark brown with grey-brow polyps (Fig.
Colonies up to 60 cm in height, fan-shaped, uniplanar with irregular branching. The stem is coloured brown with yellow to pale-grey polyps that tend to be more brightly coloured towards the end of the colony's branches (Fig.
Colonies up to 50 cm in height, bushy, with dense, short branches. Polyps are small, but numerous, giving the colony a fuzzy appearance. Dark brown to black with pale white to purple polyps (Fig.
Colonies small (typically ~ 10 cm in height), with sparse, dichotomous branching and a twig-like appearance. No visible polyp calices. Dark red to dark brown.
Colonies up to 40 cm in height, fan-shaped, appearing mostly uniplanar and heavily branched. With conspicuous polyps giving the colony a fuzzy appearance. Multi-coloured with a pale white base, a dark-red to purple middle area and a bright yellow outer edge. This colouration is mostly well-developed in larger colonies (Fig.
Colonies up to 40 cm in height, fan-shaped to slightly bushy and heavily branched. Large polyps are giving the colony a fuzzy appearance. Purple to dark brown stem with yellow-orange polyps (Fig.
Colonies are short (~ 15 cm in height), irregularly branched, forming small bushes. Branches are thin and almost twig-like, giving an overall delicate and brittle appearance. The colouration is bright yellow. Observed to grow in sedimented habitats around 60 m. The species could be confused with
Colonies up to 40 cm in height, displaying uniplanar to bushy branching. Conspicuous polyps give the colony a rather fuzzy appearance. The colouration is a pale yellow to brown, with the polyps slightly darker coloured than the colony main colour (Fig.
Colonies typically < 20 cm in height, but some up to 55 cm tall, growing as uniplanar, irregularly branched fans. Branches thin with large polyp calices giving the colony a spiky appearance. Anastomoses are never observed. Colour shades of red to brown with yellow polyps. Species of
Colonies up to 50 cm in height, with thin branches and uniplanar growth form, with side branches much shorter than main branches. Some degree of anastomoses should always be present. Polyp calices are conspicuous and give branches a bumpy appearance. Colonies are red-brown to grey, with one white individual recorded. The similar-looking
Colonies up to 60 cm in height, uniplanar and profusely branched. With a thick central stem and visibly thinner branches. Colour observed here was a distinctly bright red, with pink, yellow and pale-blue also common (Fig.
Colonies < 50 cm in height, fan-shaped and uniplanar. Dense, fine branches displaying a high degree of anastomoses, giving the colony a mesh-like appearance. Colour pale yellow-green to grey (Fig.
Colonies typically ~ 20 cm in height, fan-shaped, densely-branched, with fine branches and a strong tree-like appearance. The colouration of the branches is a light orange that tends to have a reddish tint (Fig.
Colonies up to 40 cm in height, sparsely branched, with thick branches starting from the base of the colony; large polyp calyces give branches a serrated appearance. The colouration of the colony is light pink (Fig.
Colonies are fan-shaped and uniplanar. Branches display a high degree of anastomoses, forming net-like fans. Stalks are always attached to hard substrates. Colouration ranges from red to orange and yellow. Some colonies are larger than 2 m across. Often with crinoids commensals. The three known species of
Colonies are thickly encrusted to massive and hemispherical, made up of upright, connected, parallel tubes that house a single polyp. Colonies can form step-like morphologies, growing on multilevel, horizontal platforms. Polyps are typically extended and visible. The skeleton of live individuals is always covered by polyps. The colouration of the skeleton is bright to dark red, with tentacles coloured in variations of pale, cream, green and white. Maximum recorded size: 55 cm across (Fig.
Colonies up to 30 cm, cylindrical with dome-shaped summits. Can sometimes show branching (not observed here). Polyps found exclusively on the upper colony surface. Polyps have varying contractility, but are never fully retracted. The colouration of stalks is often similar to the polyps' colouration, ranging from white, yellow, cream, brown to dark brown (Fig.
Colonies up to 20 cm in height, flat and fan-shaped, displaying dense, dichotomous branching. Polyps are numerous, giving the colony a fuzzy appearance. Light blue colouration with dark blue polyps (Fig.
Colonies typically ~15–20 cm in height, fan-shaped and heavily branched. Colour deep purple with lighter coloured polyps (Fig.
Branching colonies up to 20 cm in height. Branching starts from the base of the stalk. Colour in shades of red to brown and orange (Fig.
Colonies up to 30 cm in height, fan-shaped, growing uniplanar. Dichotomously branched. Dark grey to black colour (Fig.
Colonies up to 50 cm in height, fan-shaped, growing in multiple planes. Conspicuous central stem with many side branches. Branches appear fuzzy due to conspicuous polyps. Colour pink to fuchsia with polyps covered similar to the main colour, yet slightly lighter (Fig.
Colonies are columnar, plating or branching. Maximum recorded size: 60 cm across. As the only octocoral genus with a massive aragonite skeleton, it is often mistaken for a scleractinian coral. However, its colonies have a unique blue to green colouration with large pore-like polyps of white colour that are often visible, both in-situ and on video footage (Fig.
Wide range of morphologies; in the present survey, commonly digitate, branching or tabular. In this survey, colony size was typically < 40 cm across. Visually distinct corallites, 0.7 to 1.3 mm in diameter, cylindrical in appearance. A key feature of this taxon are its differentiated axial corallites located at the tips of branches that are often pale or white; this should not be confused with bleaching-induced colour changes. Commonly in shades of brown, although other colours can occur (Fig.
Colonies are massive, plating or encrusting. Maximum recorded size: 80 cm across. Polyps are conspicuous with corallites between 1.6 to 2.2 mm (typically distinguishable on video footage); resembling jet engines, sometimes of irregular sizes, always tightly packed. Coenosteum is typically spinous or flaky, giving colonies a granular appearance. Colourations range from pale-brown tones to dark orangy-brown. Can be confused with
Colonies are sub-massive or thickly encrusted often with thick club-like branches or robust cylindrical branches. Maximum recorded size: 1 m across. Corallites up to 4.0 mm in diameter. Colours range from cream, pale brown to green. Can be confused with
Colonies are thickly encrusting, sub-massive, plating. Maximum recorded size: 1.2 m across. Corallites are extremely small (0.25 to 1.0 mm) and thus not visible on video footage. Very rough, grainy texture, often with several bumps on colony surface. Colours ranging from beige to dark shades of brown, some species with variable additional pigmentation like purple, red and violet (Fig.
Colonies are massive or encrusting with laminar margins. Maximum recorded size: 35 cm across. Corallites are immersed with distinct, steeply sloping acutely ridged walls whose ridges can appear pale, giving the colony a honeycomb-like appearance. Corallite size 3.0 mm in diameter. Colours range from yellowish to shades of light and dark brown.
Colonies typically small (~ 20 cm in the longest dimension), although some were up to 90 cm, encrusting or plating, unifacial and contorted. Polyps usually without distinct walls and larger than 5 mm in diameter. Growth form tends to change with depth: deeper colonies found in mesophotic depths are often laminar with a white edge. Widely spaced corallites that may be inclined to the margin, that can cluster within pockets (raised rounded walls). Appearance is wavy, granulated or waxy; deeper plating forms with small bumps on the colony surface. Colour ranges from pale to lighter shades of yellow-brown.
Colonies typically < 40 cm in the longest dimension, massive, columnar, laminar or encrusting, sometimes contorted. Laminar colonies are bifacial. Corallites between 0.5 to 3.0 mm in size, walls poorly developed or absent, centres in small shallow depressions surrounded by acute ridges. Colours range from beige to darker shades of brown. Might be confused with
Small (typically < 10 cm) branching colonies. Branches ending in tubular corallites. Corallites have high, thin walls with well-defined septa. Colouration normally dark green or black, in our survey orange or grey (Fig.
Colonies are tall with thick, erect branches. Maximum recorded size: 30 cm across. Corallites sparse, tubular and are clearly discernible both in-situ and on video footage. Colouration is dark green or black.
Colonies are laminar, columnar, dome-shaped or foliaceous. Maximum recorded size: 1.3 m across. Frequently contorted; laminar and foliaceous growth forms often with paler margins. Corallites usually only on one surface, round and well-spaced from each other; often form tubular raised mounts giving the coral a bumpy texture. Corallite size 1.5 to 4.0 mm. Smooth coenosteum. Colouration ranging from beige to shades of brown and green.
Massive or encrusting colonies, predominantly cushion-shaped or irregularly following the substrate. Maximum recorded size: 20 cm across. Corallites are between 3.5 to 6.0 mm, plocoid, cylindrical with relatively large, visible gaps. Septa are large and form tall, sharp points that are visible underwater. Tentacles can be extended during the day. Colours can be green to brown with yellow variants observed at Desroches (Fig.
Solitary, free-living. Forms elongated discs with an axial furrow that may extend to reach the colony edge. Septa are alternating and are non-continuous from the axial furrow to the sides. The maximum recorded size in this survey was 30 cm (length), although specimens can grow >1 m and also appear y- or x-shaped. Belongs to either
Solitary, free-living, except juveniles of
Free-living, flat, domed or bell-shaped and oval growth forms are commonly observed. Maximum recorded size: 30 cm across. Corallites 6.0 mm. No axial furrow, but septo-costae radiate out from the centre towards the margin. Corallites are often white. Colouration pale brown with bright pink or purple margin (Fig.
Colonies can be massive, flat or dome-shaped or, as observed here, encrusting. Maximum recorded size: 50 cm across. Corallites raised unevenly from the coenosteum, giving the colonies a bumpy appearance. Corallites are 2.5 to 6.0 mm in diameter. Colouration shades of brown, but tends to have a white upper surface with darker corallites.
Colonies are thickly encrusting or laminar. Maximum recorded size: 1 m across. Large, round or oval protuberant corallites that are visible underwater, 4.0 to 15.0 mm in diameter. Septa are numerous and form visible ridges running along the surface towards the edge of the colony; the colony edge appears serrated. Septa resemble dripping candle wax. Corallites are scattered and often separated by a gap of several mm. Colouration brown, commonly with pale or whitish scalloped edges.
Colonies are massive, sub-massive or flat-topped. Maximum recorded size: 50 cm across. Most colonies in this survey with corallites forming valleys of varying length, resembling ear-lobes or meandering ridges. Often with spiky appearance due to large skeletal teeth. Large corallites that range in size from 13.0 to 35.0 mm. Colours range from brown and greyish-green to bright orange and shades of purple.
Massive, sub-massive or encrusting colonies. Maximum recorded size: 50 cm across. Corallites are highly plocoid to almost-cerioid, roughly equal in size and do not share walls. Corallite size can range from 3.0 to 25.0 mm. Colouration shades of beige, brown or green. Sometimes confused with
Colonies encrusting, laminar or branching. Maximum recorded size: 1 m across. Corallites are plocoid, uniformly shaped and elevated from the colony surface, 3.5 to 4.5 mm; they are often visible on video footage. The surface of the colony appears rough due to irregularly shaped septo-costae with spines. Colour shades of brown to grey with brightly coloured corallite centres (green) and white growing edges.
Colonies massive, sub-massive or encrusting. Maximum recorded size: 60 cm across. Corallites are cerioid, with oblong or polygonal calyces of even size, between 3.0 to 25.0 mm across; they share walls that can be smooth or serrated-looking. Colours vary from brown to yellow and sometimes orange or green.
Colonies massive, sub-massive, plate-like or encrusting. Maximum recorded size: 80 cm across. Corallites are cerioid, uniformly shaped and 3.5 to 14 mm in diameter. The septo-costae are neatly arranged around the corallite chalices, giving them a serrated appearance. Colour shades of brown.
Colonies massive, encrusting or branching. Maximum recorded size: 30 cm across. The colony surface is covered in skeletal bumps (‘hydnophores’) that appear as lemon-squeezers or juicers, with small corallites, 3.0 to 4.0 mm in size, clustered in between. Hydnophores are often brighter than the corallites, with the latter being commonly brown to grey-green (Fig.
Dome-shaped or laminar colonies, forming thick plates. Maximum recorded size: 30 cm across. Corallites 4.5 to 24.0 mm. With thin-walled, meandering valleys that increase in depth towards the centre of the colony. Some colonies branch towards the centre. Colour ranges from light brown to grey or green.
Colonies massive, dome-shaped or encrusting. Corallites forming dense meandroid valleys, giving the colony a maze-like appearance. Maximum recorded size: 40 cm across. Corallite size between 4.0 to 6.0 mm. Colour typically shades of brown or green. Can look similar to some meandering colonies of
Colonies massive appearing thickly encrusting. Maximum recorded size: 20 cm across. The colony surface consists of monocentric to meandroid, thin and ragged walls forming large valleys. Paliform lobes are commonly observed. Corallites between 12.0 to 15.0 mm in diameter. Colouration shades of brown.
Colonies are massive or form thick plates. Colony surface entirely covered in bubble-like, teardrop-shaped vesicles. Meandroid with short widely spaced valleys that are only visible when vesicles retract. Maximum recorded size: 1.5 m across. Corallites 18.0 mm in diameter. The colouration of the vesicles is always pale-whitish (Fig.
Colonies branching. Morphology depends on the environment, with thicker, stubby branches common in high-energy environments. Maximum recorded size: 30 cm across. Corallite size is 1.1 mm. In deeper, more sheltered waters, branches are thinner and more open. Colony surface covered in skeletal bumps (‘verrucae’) giving a rather spiky/rough appearance. The corallites’ darker colouration gives the coral a “black peppered” appearance (Fig.
Colonies are branching with branches shorter than those of other species of its genus. Morphology correlated to environmental parameters with colonies in calmer waters being more open and branched and colonies in high-energy environments appearing more compact. Maximum recorded size: 35 cm across. Colouration normally pale-brown, but can appear greenish and pink.
Colonies branching or encrusting. Morphology is correlated to wave action energy levels of the surrounding environment - higher wave action leads to a more compact and dense growth of the colony. Branches have blunt ends and can be very thick. The surface appears rough and the corallites are very small, 1.0 mm in diameter and hooded towards the end of each branch. No verrucae present. Branches resemble teddy bear legs due to their thick appearance. Maximum recorded size: 30 cm across. Colouration pale brown.
Massive, sub-massive, encrusting or branching colonies. Maximum recorded size up to 1 m across, except for some colonies that become hemispherical to helmed-shaped and can be several metres across. Branching colonies have stubby branches with pale tips. Corallites are very small, 0.6 to 1.3 mm and a close-up or a high-resolution camera is needed to distinguish them underwater; the surface of the colony is smooth, giving the coral an almost rock-like appearance. Colours include shades of brown or green (Fig.
Colonies with a range of growth forms; in this survey, mostly massive. This genus is easily recognised by the long, fleshy polyps that are extended day and night. Maximum recorded size: 1 m across. Corallites between 2.2 and 5.0 mm in size.
Colonies laminar and unifacial to branched and bifacial; also encrusting. Surface covered in a series of concentric ridges that are either parallel to colony margins or contorted. Corallites 0.5 mm in diameter. Most abundant in mesophotic waters, where it forms plating colonies several metres long. Colouration shades of brown with white laminar margins.
Colonies thickly encrusting to massive. Conspicuous, elliptical to round polyps, typically discernible underwater. Colour shades of creamy-white. Maximum recorded size: 50 cm across. This group likely contains a variety of species that are difficult to identify from video footage; hence, no attempt was made to identify them at a lower taxonomic level. Zoanthids can be distinguished from other Anthozoans by their tendency to incorporate sand and small pieces of the substrate into their tissue (Fig.
Often colonial, with varied branching forms and dimensions (few millimetres to few tenths of centimetres). Colouration variable. Aggregations of hydroid colonies commonly overgrow rocks and portions of dead corals. Some hydrozoans bear resemblance to octocorals, but the latter have a much more solid structure and tend to be larger. This group likely contains a variety of species that are difficult to identify from video footage; hence, no attempt was made to identify them at a lower taxonomic level. Members of the
Colonies encrusting or branching, either thick and heavy with lobed projections or cylindrical branches. Bumpy texture with almost no gaps between bumps, but smooth surface. Generally following the substrate, colonies can appear massive or look like large plates. Colouration pale brown to yellow or whitish. Branched colonies normally have pale to whitish tips. Maximum recorded size: 1 m across. In general,
Colonies are fan-shaped with fine branches typically growing in one plane. Colouration dark brown to black. Resemble sea fans, but can be distinguished by their extremely fine branches and very dark colouration. Commonly known as tree or sea fan hydroids (Fig.
Colonies delicately branched with branches ending in sympodial fashion. Maximum recorded size: 60 cm tall. Commonly growing in caves or underneath ledges. Branch surfaces are covered by dactylophores. Colouration observed was pale white, with orange, red, pink, purple and yellow possible (see the colour change in the collected specimen in Fig.
Colonies form thin, unbranched stalks. The surface is covered in dactylopores. Colouration observed here was pale white. Maximum recorded size: 10 cm in height. Commonly known as lace coral (Fig.
Colonies irregularly branched in one plane, with stem stiff and unfascicled (i.e. with a single perisarc tube). Hydrothecae relatively prominent, pedicellated, not annulated and without nematothecae. Colouration yellowish to reddish (Fig.
While most ctenophores are present in the water column, ctenophores belonging to the order
Five tapered, triangular arms merging into a conspicuous central disc. Smooth body surface. Arms are light orange to yellowish with the body darker. These specimens are showing a reverse colour pattern, resembling a miniature sea star in a darker orange on the central disc between the arms. Maximum recorded size: 18 cm across (Fig.
Four to five slightly tubular, thick arms with rounded tips. The central disc is inconspicuous and the arms appear to almost seamlessly merge into one another at the base. The surface appears smooth. Dark blue colour, sometimes purple or light orange. Maximum recorded size: 11 cm across. The captured individuals could belong to the
Ten long and tapered arms merging into a small central disc. The surface is covered in small bumps and appears rough. Colouration is bright orange on the dorsal surface, with a lighter coloured edge around the sides of the organism (Fig.
Multiple long heavily bent arms merge into a conspicuously rounded central disc. The overall surface appears smooth. Arms are of light orange colour with the central disc coloured in dark orange to red (Fig.
Five tapered arms and a rough, spiny surface. Inconspicuous central disc. Colour of the body is beige with brown patches covering the disc and arms (Fig.
Five tapered arms merging into the central disc. Appearance varies and individuals can be slender to thick-bodied with stubby and rounded or slim and highly tapered arms. Smooth body surface. The main body is pale whitish or yellowish-orange. Approximately 7 cm across.
The individual might belong to
Five short tapered arms merge into a conspicuous central disc. Maximum recorded size: 15 cm across. The overall surface appears smooth, but the collected specimen displayed some very small bumpy projections. Orange colour (Fig.
Five short triangular arms and a wide central disc, ~ 10 cm across. Rough surface with small bumpy projections. Colouration is a light orange mottled in darker orange patches with a conspicuous seastar-shaped darker patch in the centre (Fig.
Five short, tapered arms and large central disc. Maximum recorded size: 10 cm across. The Latin name of this sea star translates to "star-shaped tile", describing tile-shaped plates covering the entire dorsal body surface. The main body is darker orange or yellow with slightly lighter coloured arm tips (Fig.
Five tapered spiny arms and a large central disc. Body surface covered in short spine-like projections and bumps. The main body is pale brown with lighter brown to pale whitish spines (Fig.
Five tapered arms and conspicuous central disc. The main body is dark red and the plates are creamy light brown to orange. Sometimes whitish. The central disc and the tips of the arms are darker. Maximum recorded size: 10 cm across. The collected specimen was
Five short, stubby arms and a large central disc. The edge of the starfish is slightly ridged. Maximum recorded size: 10 cm across. Darker main body with lighter edge and arm tips. Orange colour (Fig.
Five short, triangular and stubby arms with a large central disc. Maximum recorded size: 8 cm across. Dark orange with arm tips appearing lighter orange to yellow (Fig.
Five tapered, slender arms and inconspicuous central disc. Maximum recorded size: 19 cm across. Rough body surface covered in small bumps. The main body is pale brown to yellow, displaying cryptic mottled colour patterns that make them blend in with the substrate (Fig.
Five tapered slender arms merging into an inconspicuous central disc. Maximum recorded size: 18 cm across. Smooth body surface. The main body is pale orange to yellow (Fig.
Five tapered and slender arms and smooth body surface. The body colour is dark green (Fig.
Five short stubby arms that rarely protrude from the wide central disc. Maximum recorded size: 23 cm across. Smooth surface. Appears roughly pentagonal in shape. Colouration is a uniform light grey. Possible genera could be
Five stubby, triangular arms merging into a cushion-like central disc. Maximum recorded size: 16 cm across. Roughly pentagonal appearance with a leathery surface. The aboral surface is covered in small conical spines. Colouration can vary, but most commonly a light greyish base colour with small pink patches adjacent to black tubercules (Fig.
Five stubby, triangular arms merging into a cushion-like central disc. Approximately 15 cm across. The body appears inflated with a smooth surface. Colour is a light brownish-grey with a dark brown edge and arm tips (Fig.
Can be free-swimming or anchored to the substrate by a stalk. The mouth is located on the upper surface surrounded by a crown of feeding arms. Appendages displaying pentameral symmetry are often subdivided into ten or more arms and covered in feather-like pinnules. Colours can vary, in our survey mostly dark black and white, brown, pink and yellow. Stripes commonly observed. This group likely contains a variety of species that are difficult to identify from video footage; hence, no attempt was made to identify them at a lower taxonomic level (Fig.
Thick spines of varying lengths. The longest spines are curved, whilst shorter ones are straight. The body surface is almost entirely covered in spines, with naked and vertical spaces alternating along the body. The main body appears in a dark brown with spines being bright red and white, some with white bands towards the tips, some coloured half and half and others uniformly red. Maximum recorded size: 30 cm across. Positive species identification requires microscopic examination. Collected specimens belonged to
(Fig.
The body surface is entirely covered in fine needle-like spines that are longer than the body is wide. Maximum recorded size: 15 cm across. The main body is appearing globular, orange-brown in colour with similar coloured spines and a conspicuous predominantly white anal cone (Fig.
Thick spines pointed and longer than body width. The body surface appears smooth, but is covered with shorter spines that are encircling the attachment areas of the longer spines. Maximum recorded size: 25 cm across. Colour a pale white to cream brown. Positive species identification requires microscopic examination. Collected specimens belonged to
Thick spines longer than body width. Length of spines varies, with ventral ones shorter and dorsal ones longer. The body surface is covered in short inconspicuous spines in between larger, more prominent ones. Maximum recorded size: 10 cm across. Colour a dark red with spines pale white (Fig.
Thick, somewhat pointed spines longer than body width. The main body is very small in comparison to the spines and the body surface is almost entirely covered in spines. Maximum recorded size: 15 cm across. Colour a dark brown with the base of spines pale brown and dark brown to dark red towards the tips (Fig.
The body is dome-shaped and covered in short and fine spines, giving a smooth appearance from a distance. Maximum recorded size: 15 cm across. The main body is of light brown colour with darker pores that form a pattern on the dorsal side that resembles the outline of opened petals. Found on sand or in seagrass habitats, in deeper water often covered in seagrass fragments. Positive species identification requires microscopic examination. Collected specimens belonged to
Spines are roughly equal to the diameter of the body. Maximum recorded size: 14 cm across. Primarily found in crevices, but can form aggregations in the open. Colour a uniform black, juveniles can have banded spines. Commonly known as Short Spine Urchin. Spines are noticeably shorter than those of
Spines shorter than body width and of uniform length. Maximum recorded size: 20 cm across. Colouration variable, from dark red to pale orange with distinct white bands or a pale white with distinct red bands. Positive species identification requires microscopic examination. Collected specimens belonged to
The body surface is almost entirely covered in spines of varying lengths that tend to be thicker and longer towards the dorsal surface of the main body. The main body appears in a dark red with white spines. Maximum recorded size: 6 cm across.
Spines shorter than body width and of uniform length. The body appears egg-shaped and not as globular as other urchins observed here. Maximum recorded size: 12 cm across. Colour a dark red with distinct white patches. Spines all coloured dark red (Fig.
Two possible species,
Commonly known as "Lollyfish", this holothurian has a smooth, slender body that slightly tapers towards the ends. The body is often covered in sand, only leaving out small dotted areas on its dorsal surface. Body colour is black (Fig.
Commonly known as "edible sea cucumber", this holothurian has a smooth body that slightly tapers towards the ends. Darker, blackish dorsal surface and reddish or beige underside. Maximum recorded size: 35 cm long (Fig.
Body surface covered in spike-like papillae, but otherwise smooth. Square body cross-section. Approximately 10 cm long. Colouration dark red (Fig.
Commonly known as "Prickly Redfish", the body surface of this sea cucumber is almost entirely covered in spike-like papillae. Large (up to 50 cm long in this survey) and heavy-bodied with a square body cross-section. Colouration bright orange to greenish in deeper waters, with pink, red and brown common in shallow water (Fig.
Tube-dwelling worms with highly modified branchial crowns that form large fans. Crowns appear feathery and are separated into two clusters. Colours can vary and range from white to brown. Some species brightly coloured in pink, blue or green. Here orange. This group likely contains a variety of species that are difficult to identify from images; hence, no attempt was made to identify them at a lower taxonomic level (Fig.
Extremely large-bodied clams with four to five distinct folds in its shell. The mantle is always visible, even when the shell is closed and covered in hundreds of small spots. Shell colour can vary and is often determined by organisms growing on it (such as algae or CCA), the mantle is normally of a dark brown to bluish-purple colour (Fig.
A spherical sponge that resembles an upside-down teardrop with a tapered, singular oscule. Maximum recorded size: 5 cm long. Individuals emerge from a stubby conspicuous stem. Pale-whitish colouration (Fig.
Erect flabellate sometimes fan-shaped with a short stalk. Maximum recorded size: 30 cm long. The surface appears rough, convoluted and crinkly with shallow ridges. Colour dark red (Fig.
Thickly encrusting, plate-like sponges; buried in sand, with groups of tubes exposed with conspicuous terminal oscules. Maximum recorded size: 1 m across. Tubes growing more towards the centre of the individual sponge tend to be volcano-shaped and larger with multiple oscules. Colour is dark green to black (Fig.
Thickly encrusting sponges with groups of tubes clustered around one or two central, conspicuous, volcano-shaped main tubes with multiple oscules. Maximum recorded size: 50 cm across. Surface undulating and texture tough. From the top, the sponge looks like a volcano. Colour is green (Fig.
Barrel sponge with a smooth surface. Maximum recorded size: 20 cm across. Singular, very conspicuous terminal oscule. Can be covered in epifauna. Colouration creamy-brown (Fig.
Thin, soft, encrusting sponge with surface uplifted into low conules, otherwise smooth. Oscules mounted at the end of oscular chimneys. Maximum recorded size: 40 cm across. Red or green colouration (Fig.
This sponge forms groups or chains of tubes with conspicuous terminal oscules. Tubes can become very elongated, almost fan-like in some cases. Branching originates at the base. Maximum recorded size: 40 cm across. The surface is covered with small spiny projections, giving the sponge a rough appearance. Colour ash-grey (Fig.
Sponges form encrusting to laterally spreading masses of branches and protrusions, shaped somewhat finger-like. Maximum recorded size ~ 30 cm. Inconspicuous oscules. Surface smooth with a velvety touch. Texture very soft. Colour greenish to grey. Other members of this group have large, irregularly spaced oscules that lack raised edges (Fig.
Morphology can vary from thin encrusting to laterally spreading masses of branches and protrusions. Maximum recorded size: 50 cm across. Can form tubes as seen above. Oscules either spread across the surface or at the top of tubes. Colour purple to grey (Fig.
Thin encrusting sponges that can have singular, chimney-like protrusions. Maximum recorded size: 15 cm across. Oscules either spread across the surface or at the top of tubes. Colour greenish to pale-grey (Fig.
Encrusting sponge with multiple small oscules prominent. Maximum recorded size: 20 cm across. The surface appears smooth. Irregular knobs or lobes are present. Might be covered in epifauna. Colour cream brown to greenish. Specimens belong to either
Encrusting sponge with multiple oscules on the surface; surface smooth with a stony appearance. Maximum recorded size: 10 cm across. Sometimes irregular knobs or lobes present. Might be covered in epifauna. Colour cream brown to orange or red. Specimens belong to either
A massive sponge (up to 50 cm across) that appears smooth with a stony, velvety texture. Forms irregularly shaped masses that resemble rocks. Colouration mottled with yellow, greenish and brown patches (Fig.
A massive sponge that forms large barrels. The maximum recorded length was 32 cm, although they can often reach > 1 m. While the outside surface is heavily ridged, the inside appears smooth with a stony, velvety texture. Dark brown colouration (Fig.
Thick encrusting to massive sponges with a rough surface dominated by prominent oscules. Maximum recorded size: 25 cm across. Grey-whitish colouration (Fig.
Encrusting or massive sponge up to 1 m long, with a smooth surface. Surface area covered in inconspicuous oscules across. Can be observed as a singular encrusting mass or as a group of multiple small sponges. Colouration black (Fig.
Branching sponge with thick, ramose branches and a rough surface. Maximum recorded size: 35 cm across. Colouration dark brown, but mottled throughout with bright yellow patches (Fig.
Thickly encrusting, sub-massive to fan-shaped morphology. Short stalk present in the fan-shaped form with thick, fleshy lobes. Maximum recorded size: 30 cm across. The surface appears rough, crinkly and conulose, corrugated longitudinally with shallow ridges. Oscules are inconspicuous and spread throughout the surface. Colour dark orange to orange-yellow (Fig.
Flabellate: either fan-shaped or branching. Forms short stalk with fleshy, blade-like lobes or erect, expanded leaves. Maximum recorded size: 31 cm across. The surface appears rough and crinkly, corrugated longitudinally with shallow ridges. Colour orange to pink.
Globular sponge with a smooth surface. Maximum recorded size: 17 cm across. Singular terminal oscule very conspicuous in the darker coloured morphotype. Colouration pale grey to a dark brown (Fig.
Cup-shaped sponge with a smooth, velvety surface. Up to 22 cm across; however, the majority ~ 10 cm. The funnel-shaped cup is anchored to the substrate with a short, stubby stem. Texture hard. Colour whitish to pale yellow (Fig.
Massive or thickly foliose sponge with very rough, hispid surface. Maximum recorded size: 50 cm across. Rock hard texture. Colouration whitish with yellow to greenish patches (Fig.
Encrusting morphology, sometimes forming shallow tubes. Maximum recorded size: 10 cm across. Large oscules at the end of tubes. Colourations pale whitish to beige (Fig.
Globular sponge with a warty surface; inconspicuous singular terminal oscule. Maximum recorded size: 20 cm across. Can be covered in epifauna or sediment. Colouration yellow (Fig.
Tube-shaped sponge with tubes growing in a cluster that originates from a broad base. Maximum recorded size: 40 cm across. Conspicuous oscules at the terminal end of slightly tapered tubes. Smooth, velvety surface. Maroon-brown to dark brown colouration. Can be confused with
Thickly encrusting sponge, sometimes with shallow, bumpy tubes. Maximum recorded size: 15 cm across. Conspicuous, terminal oscules that can appear clustered on the surface, giving it a mammiform appearance. Smooth, velvety surface. Dark brick-red colouration (Fig.
Encrusting sponge with a velvety smooth surface texture. Colouration creamy brown, sometimes mottled with yellow patches. This group likely contains a variety of species belonging to different families; however, consistent positive identification was not always possible (e.g. due to distance from the camera) and, in most cases, requires microscopic examination. Observed genera included
Encrusting sponges of variable thickness and surface texture. Colouration shades of orange. This group likely contains a variety of species belonging to different families; however, consistent positive identification was not always possible (e.g. due to distance from the camera) and, in most cases, requires microscopic examination. Observed genera included
Encrusting sponges of variable thickness and surface texture. Colouration bright red to dark red and red-brown. This group likely contains a variety of species belonging to different families; however, consistent positive identification was not always possible (e.g. due to distance from the camera) and, in most cases, requires microscopic examination. Observed genera included
Encrusting sponge with a bumpy or rough surface texture. Bright yellow to pale yellow. This group likely contains a variety of species belonging to different families; however, consistent positive identification was not always possible (e.g. due to distance from the camera) and, in most cases, requires microscopic examination. Observed genera included
A massive-globular sponge, less than 10 cm across, that creates a single giant basal spicule to anchor itself in the sediment. Smooth surface with rough-looking “stalk”. Colouration pale white (Fig.
Cup-shaped sponge with a smooth surface and serrated edge. Typical recorded size: 10 cm across. Individuals appear rather flat and form roughly oval masses. Pale-whitish colouration (Fig.
Branching sponge that can appear twig-like or fan-like in larger individuals due to its heavily branched appearance. Typically between 25 to 30 cm in height, although individuals can grow > 50 cm. Raised oscules that resemble corallites in hard corals. Colour light yellow. Somewhat resembles hard corals if not for the depth where it is found. (Fig.
Encrusting sponge with multiple small oscules; surface smooth, but irregular, uneven with a soft texture. Maximum recorded size: 30 cm across. Colour pale brown to yellow, orange and purple. Commonly known as “chicken liver” sponges because of their fleshy texture. These sponges are soft. It is typical of the group in that the internal colour is virtually identical to the external colour (Fig.
A foliose sponge that resembles lettuce. Maximum recorded size: 28 cm across. Flower-like appearance with irregular edges. Dark green colouration (Fig.
All underwater images were acquired from video data; hence, special thanks to the SCUBA divers (Nekton, Blue Safari and Island Conservation Society) and pilots (ROV support and Global Sub Dive) operating the ROV and mini-ROV (ROV Support A/S, Kolding, Denmark) and the two submersibles (Triton submersibles, Vero Beach, Florida, USA), respectively. We would also like to thank Emma Deeks, Francesca Sahit and Molly Rivers for helping with the initial screening of underwater footage and helping with the compilation of morphotype lists. We also thank Denise Swanborn for helping us create a map of our surveyed sites including the collected multibeam bathymetry data. Furthermore, we would like to thank the Seychelles Government, namely the Ministry of Agriculture, Climate Change and Environment and all our other Seychelles partners (Seychelles Fishing Authority, The Ministry of Fisheries and the Blue Economy, The Seychelles Tourism Board, The Ministry of Foreign Affairs and Tourism, University of Seychelles, Seychelles Island Foundation, Marine Conservation Society Seychelles, The Nature Conservancy, The Seychelles Conservation and Climate Adaptation Trust, Nature Seychelles, The Island Development Company, The National Institute of Science and Technology and The Seychelles National Parks Authority) for helping us with the planning and execution of the Expedition. We wish to thank Omega and Kensington Tours for their generous funding and our strategic partners for their in-kind contributions. Special thanks go out to National Research Foundation, South African Institute of Aquatic Biodiversity for hosting our taxonomic ID workshop and everyone who attended it, helping with the finalisation of our species identification lists and the identification of collected specimens. Finally, thanks to all the Expedition participants, the crew of the
LCW and PVS designed fieldwork data collection and, together with KNS, NF, JM and RW, collected the video and biological specimens in the field. LW served as the chief scientist on the First Descent: Seychelles 2019 expedition. NF and PS annotated the collected footage and placed them into an initial set of morphotypes. Further taxonomic identification was conducted in collaboration with JAM and LM (
Map of the seven surveyed sites around Seychelles Outer Islands. Multibeam data were overlaid to show survey areas. Sites are listed from west to east.
Survey site mean coordinates:
1) Aldabra West 1 (
2) Aldabra North 1 (
3) Astove West 1 (
4) Alphonse North 1 (
5) Poivre East 1 (
6) St. Joseph* North 1 (
7) Desroches South 1 (
*St. Joseph was hereafter referred to as D'Arros due to initial naming when compiling datasets and the islands close proximity to one another.
Maps were created in ESRI using the basemaps "
D'Arros N1, 60 m.
Desroches S1, 10 m, collected specimen (SEY1_1377).
Aldabra N1, 10 m.
Aldabra N1, 10 m.
Poivre E1, 30 m.
Poivre E1, 30 m.
Astove W1, 60 m.
Alphonse N1, 60 m.
Desroches S1, 10 m.
Desroches S1, 10 m.
Astove W1, 10 m.
Astove W1, 10 m.
Aldabra W1, 250 m.
Astove W1, 250 m.
Aldabra N1, 30 m.
Aldabra N1, 60 m.
Alphonse N1, 250 m.
Alphonse N1, 250 m.
Desroches S1, 30 m.
D'Arros N1, 60 m.
Desroches S1, 60 m.
Aldabra N1, 30 m.
Desroches S1, 60 m.
D'Arros N1, 60 m.
D'Arros N1, 350 m.
D'Arros N1, 350 m.
Alphonse N1, 60 m.
Alphonse N1, 60 m.
Poivre E1, 10 m.
Poivre E1, 10 m.
Aldabra N1, 10 m.
Alphonse N1, 97 m.
Alphonse N1, 97 m.
Aldabra N1, 10 m.
Aldabra N1, 10 m.
Aldabra N1, 10 m, collected specimen (SEY1_250)
Aldabra N1, 10 m, collected specimen (SEY1_250)
Aldabra N1, 30 m.
Poivre E1, 10 m.
Aldabra W1, 10 m.
Aldabra W1, 60 m.
Aldabra W1, 60 m.
Astove W1, 60 m.
Aldabra N1, 120 m.
Aldabra N1, 120 m.
Alphonse N1, 120 m.
Aldabra W1, 30 m.
Aldabra W1, 60 m.
Aldabra N1, 100 m.
Aldabra N1, 100 m.
Aldabra N1, 30 m.
Aldabra N1, 30 m.
D'Arros N1, 120 m.
Alphonse N1, 103 m.
Poivre E1, 60 m.
D'Arros N1, 60 m.
Desroches S1, 60 m.
Aldabra N1, 120 m.
Aldabra N1, 120 m.
Astove W1, 60 m.
Astove W1, 60 m.
Aldabra W1, 30 m.
D'Arros N1, 60 m.
D'Arros N1, 60 m.
Desroches S1, 120 m.
Desroches S1, 120 m.
Aldabra N1, 160 m.
Aldabra W1, 120 m.
Aldabra W1, 32 m.
Aldabra W1, 30 m.
Aldabra N1, 30 m.
Alphonse N1, 104 m.
Alphonse N1, 97 m.
Aldabra N1, 91 m.
Aldabra N1, 91 m, collected specimen (SEY1_200) corresponding to the in-situ colony of Fig. 61c.
Aldabra W1, 120 m.
Aldabra N1, 140 m.
Aldabra N1, 148 m.
Aldabra N1, 30 m.
Astove W1, 60 m.
Aldabra W1, 120 m.
D'Arros N1, 120 m.
Desroches S1, 60 m.
Desroches S1, 60 m.
Alphonse N1, 108 m.
Alphonse N1, 100 m.
Aldabra N1, 120 m.
Alphonse N1, 107 m.
Aldabra N1, 100 m.
Aldabra N1, 100 m.
Aldabra N1, 60 m.
Astove W1, 60 m.
Aldabra N1, 60 m.
Aldabra W1, 60 m.
Aldabra N1, 120 m.
Aldabra N1, 120 m, collected specimen (SEY1_158) corresponding to the in-situ colony of Fig. 63c.
Alphonse N1, 250 m.
Alphonse N1, 242 m.
D'Arros N1, 350 m.
Aldabra N1, 190 m.
Aldabra N1, 190 m, collected specimen (SEY1_195) corresponding to the in-situ colony of Fig. 67b.
Aldabra N1, 60 m.
Alphonse N1, 60 m.
Aldabra N1, 60 m.
Aldabra N1, 30 m.
Aldabra N1, 30 m, collected specimen (SEY1_149).
Alphonse N1, 10 m.
Alphonse N1, 10 m.
D'Arros N1, 120 m.
D'Arros N1, 120 m.
D'Arros N1, 120 m.
D'Arros N1, 120 m.
Astove W1, 10 m.
Aldabra N1, 10 m.
Branching colony. Astove W1, 10 m.
Branching colony. Astove W1, 10 m.
Tabulate colony. Astove W1, 10 m.
Tabulate colony. Astove W1, 10 m.
Digitate colony. Alphonse N1, 10 m.
Encrusting colony. Aldabra N1, 10 m.
Massive colony. Aldabra N1, 10 m.
Encrusting-columnar colony. Astove W1, 10 m.
Encrusting-columnar colony. Astove W1, 10 m.
Encrusting colony. Astove W1, 10 m.
Columnar colony. Astove W1, 10 m.
Encrusting colony. Astove W1, 10 m.
Encrusting colony. Astove W1, 10 m.
Encrusting colony. Alphonse N1, 60 m.
Plating colony. Alphonse N1, 60 m.
Laminar colony. Astove W1, 10 m.
Encrusting colony. Astove W1, 10 m.
Astove W1, 10 m.
Aldabra N1, 30 m.
Laminar colony. Aldabra N1, 10 m.
Laminar colony. Astove W1, 10 m.
Massive colony. Aldabra N1, 10 m.
Massive colony. Alphonse N1, 10 m.
Desroches S1, 30 m.
Desroches S1, 30 m.
Astove W1, 10 m.
Aldabra N1, 10 m.
Poivre E1, 30 m.
Encrusting colony. Aldabra W1, 10 m.
Encrusting colony. Astove W1, 10 m.
Encrusting colony. Aldabra N1, 60 m.
Laminar colony. Astove W1, 30 m.
Massive colony. Aldabra W1, 10 m.
Massive colony. Aldabra N1, 10 m.
Encrusting colony. Astove W1, 10 m.
Massive colony. Aldabra N1, 10 m.
Encrusting colony. Astove W1, 10 m.
Encrusting colony. Astove W1, 10 m.
Laminar colony. Astove W1, 10 m.
Massive colony. Alphonse N1, 10 m.
Encrusting colony. Astove W1, 10 m.
Massive colony. Alphonse N1, 10 m.
Massive colony. Astove W1, 10 m.
Encrusting colony. Astove W1, 10 m.
Massive colony. Astove W1, 10 m.
Encrusting colony. Astove W1, 10 m.
Encrusting colony. Astove W1, 10 m.
Encrusting colony. Astove W1, 10 m.
Massive colony. Aldabra N1, 10 m.
Massive colony. Aldabra N1, 10 m.
Branching colony. Astove W1, 10 m.
Branching colony. Alphonse N1, 10 m.
Branching colony. Astove W1, 10 m.
Branching colony. Alphonse N1, 10 m.
Massive colony. Alphonse N1, 10 m.
Massive colony. Alphonse N1, 10 m.
Branching colony. Poivre E1, 10 m.
Branching colony. Astove W1, 10 m.
Sub-massive colony. Poivre E1, 10 m.
Sub-massive colony. Poivre E1, 10 m.
Laminar colony. Astove W1, 10 m.
Laminar colony. Astove W1, 10 m.
Astove W1, 10 m.
Astove W1, 10 m.
Aldabra N1, 60 m.
Astove W1, 30 m.
Alphonse N1, 10 m.
Astove W1, 10 m.
Alphonse N1, 10 m.
Alphonse N1, 10 m.
Aldabra W1, 60 m.
Aldabra N1, 250 m. (collected specimen SEY1_213)
Aldabra W1, 250 m.
Aldabra W1, 250 m. Close-up of Fig. 111a.
Astove W1, 10 m.
Astove W1, 60 m.
Specimen attached to a collected
Aldabra W1, 250 m.
Aldabra W1, 250 m.
Aldabra W1, 250 m.
D'Arros N1, 350 m.
D'Arros N1, 350 m. Collected specimen SEY1_1079.
Poivre E1, 120 m.
Poivre E1, 120 m.
Poivre E1, 120 m. Collected specimen (SEY1_724)
Poivre E1, 120 m. Back-side of collected specimen (SEY1_724)
Alphonse N1, 252 m.
Alphonse N1, 238 m.
D'Arros N1, 30 m.
Alphonse N1, 60 m.
D'Arros N1, 30 m. Collected specimen (SEY1_1154)
D'Arros N1, 30 m. Backside of collected specimen (SEY1_1154)
Alphonse N1, 250 m.
Astove W1, 250 m. Collected specimen (SEY1_603)
Astove W1, 250 m. Back-side of collected specimen (SEY1_603)
Alphonse N1, 255 m.
D'Arros N1, 350 m.
Astove W1, 250 m.
Poivre E1, 120 m.
Poivre E1, 120 m.
Poivre E1, 120 m. Collected specimen (SEY1_722).
Poivre E1, 10 m.
Poivre E1, 10 m.
Aldabra N1, 60 m.
Aldabra W1, 250 m.
Aldabra N1, 30 m.
D'Arros N1, 350 m.
Desroches S1, 230 m.
Desroches S1, 230 m. The collected specimen (SEY1_1277) has been identified as
Alphonse N1, 250 m.
Aldabra W1, 250 m. The collected specimen (SEY1_390) has been identified as
Poivre E1, 120 m.
Poivre E1, 120 m.
Desroches S1, 250 m.
Poivre E1, 250 m. The collected specimen (SEY1_0773) was identified as
D'Arros N1, 350 m.
Alphonse N1, 250 m.
Aldabra N1, 250 m. The collected specimen (SEY1_178) was identified as
Alphonse N1, 250 m. The collected specimen (SEY1_122) was identified as
Poivre E1, 120 m.
Astove W1, 350 m.
Desroches S1, 60 m.
D'Arros N1, 30 m.
Astove W1, 60 m.
Astove W1, 60 m.
Aldabra W1, 30 m.
Aldabra N1, 30 m. Collected specimen (SEY1_210)
Aldabra N1, 30 m.
Aldabra W1, 30 m.
Aldabra W1, 60 m.
Aldabra W1, 60 m.
Aldabra W1, 60 m.
D'Arros N1, 60 m.
D'Arros N1, 60 m.
Aldabra N1, 10 m.
Aldabra N1, 30 m.
Aldabra N1, 60 m.
Aldabra W1, 30 m.
Aldabra W1, 30 m.
Alphonse N1, 60 m.
Alphonse N1, 60 m.
D'Arros N1, 60 m.
Astove W1, 60 m.
Poivre E1, 30 m.
Aldabra W1, 120 m.
Alphonse N1, 60 m.
Alphonse N1, 60 m.
Astove W1, 10 m.
Astove W1, 10 m.
Astove W1, 60 m.
Astove W1, 60 m.
Aldabra W1, 30 m.
Aldabra W1, 30 m.
Poivre E1, 120 m.
Poivre E1, 120 m.
Aldabra N1, 120 m.
Aldabra W1, 60 m.
Aldabra W1, 60 m.
Aldabra W1, 60 m.
Aldabra W1, 60 m.
Astove W1, 10 m.
Aldabra W1, 30 m.
Aldabra W1, 30 m.
Astove W1, 10 m.
Aldabra N1, 30 m.
Aldabra N1 60 m.
Aldabra W1, 60 m.
Aldabra W1, 60 m. Collected specimen (SEY1_351)
Astove W1, 60 m.
Aldabra W1, 120 m.
Aldabra N1, 160 m.
Aldabra N1, 160 m.
Aldabra W1, 120 m.
Aldabra W1, 120 m.
Aldabra W1, 120 m. Collected specimen SEY1_388.
Astove W1, 60 m.
Astove W1, 60 m.
Aldabra N1, 10 m.
Astove W1, 10 m.
Astove W1, 10 m.
Astove W1, 10 m.
Alphonse N1, 60 m.
Astove W1, 120 m.
Aldabra N1, 120 m.
Aldabra W1, 250 m.
Astove W1, 250 m.
Astove W1, 250 m.
Astove W1, 250 m.
Aldabra W1, 120 m. Collected specimen (SEY1_163).
Astove W1, 10 m.
Alphonse N1, 30 m.
Aldabra W1, 60 m.
Lettuce-like green sponge
Aldabra N1, 120 m.
Aldabra N1, 120 m.
List of the 184 morphotypes observed in shallow and deeper reef habitats in the Seychelles during the First Descent: Seychelles 2019 expedition. Open nomenclature (ON) signs applicable to image-based faunal analyses (e.g. indet., stet., inc.), as suggested by
Phylum | Class | Order | Family | Genus | Species / Morphospecies Scientific Name with ON signs |
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Holothuriida |
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Holothuriida |
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Holothuriida |
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Synallactida |
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Synallactida |
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Cardiida |
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Axinellida |
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Clionaida |
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Clionaida |
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Clionaida |
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Scopalinida |
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Sceptrulophora |
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Unknown lettuce-like green sponge |