Diversity of reef organisms

A healthy reef supports a rich diversity of organisms.  CLICK ON a "hot" button to see some examples of Caribbean reef plants and animals. Throughout the VIRTUAL DIVE we’ll see these and many other reef-dwellers and will study what they do, how they behave, and how they interact. 

hot buttons for diversity section of BIOLOGY OF CARIBBEAN CORAL REEFS website diversity of corals diversity of gorgonians diversity of sponges diversity of worms diversity of molluscs diversity of crustaceans diversity of echinoderms diversity of tunicates diversity of turtles diversity of fishes diversity of sharks/mammals
icon for echinoderm-diversity section of Biology of Caribbean Coral Reefs website


There are over 400 species of echinoderms in the Caribbean Sea but, as with other types of motile reef organisms, only a fraction of the total would be seen on a SCUBA-dive in a given area, and then usually just the larger species.

seahorse dive leader sea star on sand taken from a video

"Sea stars are generally not all that common on reefs. For these cushion stars you have to be in quite shallow water over sand or, more commonly, seagrass beds" - Turks & Caicos 2003

NOTE Oreaster reticulatus

Some Caribbean echinoderms:
sea urchin Tripneustes ventricosus
West-Indian sea egg Tripneustes ventricosus. The small white dots are special defensive structures known as pedicellariae. They each consist of a pair of jaws with associated venom glands 1X
golden crinoid
Golden crinoid Davidaster rubiginosa raises its arms to filter-feed. Two other organisms are visible in the photo: a tubeworm Anamobaea orstedii and an yellowline arrow crab Stenorhynchus seticornis 0.6X
photograph of sea star
The sea star Linckia guildingii can reproduce both sexually via gametes, and asexually by dropping arms. One such arm is being regenerated in this individual 0.7X. Photograph courtesy Anne Dupont, Florida
crinoids with diver in background
Crinoids Davidaster sp. with diver in background

seahorse dive leader sea urchin on a shipwreck taken from a video These sea urchins are filmed on the deck of a shipwreck. The first is holding a few bits of seaweed against its body, possibly for camouflage protection, shading from light, or for eating later. This species Tripneustes ventricosus is locally called a "sea egg". Its gonads are tasty and are traditionally eaten from the half-shell. - St. Maarten 2005

donkey-dung sea cucumber
Donkey-dung sea cucumber Holothuria mexicana 0.5X
sea cucumber Holothuria thomasi
Mouth end of night-feeding sea cucumber Holothuria thomasi 0.3X
Sponge-inhabiting brittle
star Ophiothrix suensonii 1X
sponge-inhabiting brittle star Ophiothrix suensonii  

seahorse dive leader photo of a crinoid taken from a video This species of crinoid, possibly Nemaster grandis, likes to hang out in exposed positions on the reef, in areas of good water flow - Bonaire 2003