Georgette Douwma / Kaleidoscopic image of Sea apple (Pseudocolochirus violaceus). Komodo National Park, Indonesia.

Nick Hawkins / Orange-footed sea cucumber (Cucumaria frondosa) tentacles, Bay of Fundy, New Brunswick, Canada, July.

Sue Daly / Sea cucumber (Cucumaria frondosa), Trondheimsfjord, Norway, July.

Linda Pitkin / Sea cucumber (Pseudocolochirus violaceus) Rinca, Komodo National Park, Indonesia.

Linda Pitkin / Sea cucumber / Sea apple (Pseudocolochirus violaceus) Rinca, Komodo National Park, Indonesia.

Georgette Douwma / Sea apple (Pseudocolochirus violaceus) Komodo National Park, Indonesia.

Georgette Douwma / Sea apple (Pseudocolochirus violaceus) Komodo National Park, Indonesia.

Franco Banfi / Orange sea cucumber (Cucumaria miniata) Little Strytan dive site, Eyjafjordur nearby to Akureyri, northern Iceland, North Atlantic Ocean.

Georgette Douwma / Sea apple (Pseudocolochirus violaceus) on coral reef. It feeds by filtering the water column with its tentacular crown, successively bringing each arm into its mouth to deliver food particles. Komod...

Scott Leslie / Green Sea Urchin (Strongylocentrotus droebachiensis) barren with Orange-footed Sea Cucumber (Cucumaria frondosa), Passamaquoddy Bay, Maine

Franco Banfi / Orange sea cucumber (Cucumaria miniata) and anemone, (Metridium senile) Vancouver Island, British Columbia, Canada, Pacific Ocean

Juergen Freund / Sea apple (Pseudocolochirus violaceus) feeding, Komodo National Park, Indonesia.

Pascal Kobeh / Orange sea cucumber (Cucumaria miniata), Alaska, USA, Gulf of Alaska. Pacific ocean.

Sue Daly / Sea gherkin (Pawsonia saxicola) Pavlaison, Sark, British Channel Islands.

Scott Leslie / Orange-footed Sea Cucumber (Cucumaria frondosa) filter feeding, Nova Scotia, Canada

Birgitte Wilms / Ink-spot Ascidian (Polycarpa aurata) and Red Sea Cucumber (Cucumaria miniata) 60 feet deep, Indonesia

Shane Gross / Noble dorid (Peltodoris nobilis) resting on rocks surrounded by Sea urchins (Strongylocentrotus sp.) and Orange sea cucumbers (Cucumaria miniata), Barkley Sound, Vancouver Island, British Columbia, Ca...

Shane Gross / Underwater seascape showing Sunflower sea star (Pycnopodia helianthoides), Orange sea cucumbers (Cucumaria miniata) and Sea urchins (Strongylocentrotus sp.), Barkley Sound, Vancouver Island, British C...

Shane Gross / RF - Giant Pacific octopus (Enteroctopus dofleini) camouflaged among rocks with Sea urchins (Strongylocentrotus sp.) and Orange sea cucumbers (Cucumaria miniata), Barkley Sound, Vancouver Island, Brit...

Shane Gross / Orange sea cucumber (Cucumaria miniata) spawning, Browning Pass, Vancouver Island, British Columbia, Canada, Pacific Ocean.

Shane Gross / Basket star (Gorgonocephalus eucnemis) surrounded by Orange sea cucumbers (Cucumaria miniata) on seabed, Browning Pass, Vancouver Island, British Columbia, Canada, Pacific Ocean.

Shane Gross / Orange sea cucumber (Cucumaria miniata) spawning, Browning Pass, Vancouver Island, British Columbia, Canada, Pacific Ocean.

Georgette Douwma / Composite image of marine invertebrates on black background. Top row from left: Tube anemone (Ceriantharia), Yellow sea cucumber (Colochirus robustus), Nudibranch (Nembrotha lineolata), Squat shri...

Georgette Douwma / Composite image of echinoderms on black background. top left to right: Pineapple sea cucumber (Thelenota ananas), Yellow sea cucumber (Colochirus robustus), Frianti's starfish (Nardoa frianti),...

Georgette Douwma / Composite image of echinoderms on black background. Top row from left: Featherstar (Crinoidea), Sea apple (Pseudocolochirus violaceus). Central row from left: Mosaic cushion star (Halityle regu...

Georgette Douwma / Composite image of echinoderms on black background. SEA CUCUMBER row from left: Pineapple sea cucumber (Thelenota ananas), Leopard sea cucumber (Bohadschia argus), Yellow sea cucumber (Colochirus...

David Fleetham / Sea Apple sea cucumber (Pseudocholochirus violaceus), feeding on on passing plankton. Komodo National Park, Indonesia.

David Hall / Red sea cucumbers (Cucumaria miniata) and plumose anemones (Metridium farcimen)North Wall, Browning Pass, Queen Charlotte Strait, British Columbia, Canada. September.