David Fleetham / Sea cucumber (Holothuria pervicax) at night with Red boring sponge (Hamigera sp) in foreground. Hawaii.

David Fleetham / Tiny brittle star (Ophiothrix sp) crawling across Sea cucumber, (Bohadschia argus) Yap, Micronesia.

David Fleetham / Sea cucumber (Bohadschia argus) which has ejected a part of its internal organs called Cuvierian tubules. These significantly sticky strings are a defense mechanism designed to deter predators. Yap,...

David Fleetham / Necklace seastar (Fromia monilis) on Sea cucumber (Bohadaschia argus) Yap, Micronesia.

Constantinos Petrinos / Emperor shrimp (Periclimenes imperator / Zenopontonia rex) with parasitic Isopod (Bopyridae) and living commensally with Leopard Sea Cucumber (Bohadschia argus) Lembeh Strait, North Sulawesi, Indonesi...

Georgette Douwma / Eyed sea cucumber (Bohadschia argus) on sandy reef slope. Similan Islands, Andaman Sea, Thailand.

Georgette Douwma / Black sea cucumber (Holothuria atra) rearing up and releasing eggs and sperm. Andaman Sea, Thailand.

Georgette Douwma / Black sea cucumber (Holothuria atra) rearing up and releasing sperm. Andaman Sea, Thailand.

Georgette Douwma / Leopard sea cucumber (Bohadschia argus) Lembeh, Sulawesi, Indonesia.

Georgette Douwma / Leopard sea cucumber (Bohadschia argus) Lembeh, Sulawesi, Indonesia.

Juergen Freund / Dried Sea cucumbers (Holothuria) Yadua Island, Bua Province, Fiji, South Pacific. August 2013

Juergen Freund / Dried Sea cucumbers (Holothuria) Yadua Island, Bua Province, Fiji, South Pacific. August 2013

Pete Oxford / Sea cucumber (Bohadschia sp) Rainbow Reef, Fiji, South Pacific.

Pete Oxford / Blackspotted sea cucumber (Bohadschia graeffei) on coral reef, Fiji, South Pacific.

Pete Oxford / Pink and Black Sea Cucumber (Holothuria edulis), Fiji

Alex Mustard / A male sea cucumber (Holothuria tubulosa) rears up from the seabed and releases a stream of sperm. Spawning of this species has been reported to be synchronised with lunar phases, however this photo w...

Alex Mustard / A male sea cucumber (Holothuria tubulosa) rears up from the seabed and releases a stream of sperm. Spawning of this species has been reported to be synchronised with lunar phases, however this photo w...

Norbert Wu / Sea Cucumber (Holothuria fuscogilva), Ambon, Indonesia

Juergen Freund / Sea cucumber (Bohadschia marmorata) discharging sticky threads as a defence mechanism, Palawan, Philippines.

Juergen Freund / Sea cucumber (Bohadschia marmorata) on seabed, when threatened it discharges sticky threads in defence, Palawan, Philippines.

Juergen Freund / Sea cucumber (Bohadschia marmorata) discharges sticky threads as a defense mechanism when threatened, Palawan, Philippines, Indo-pacific.

GEORGETTE DOUWMA / Black sea cucumber (Stichopus chloronotus) on seabed, Indonesia

Tom Vierus / Graeffe's sea cucumber (Pearsonothuria graeffei) on a coral bommie near 'Shark Point', Munda, Western Province, New Georgia, Solomon Islands, Pacific Ocean.

Joel Sartore / Photo Ark / Black sea cucumber (Holothuria leucospilota) portrait, from the Gulf of Oman. Captive.

Joel Sartore / Photo Ark / Sand sea cucumber (Holothuria arenicola) portrait, from the Gulf of Oman. Captive.

Tony Wu / Male Leopard sea cucumber (Bohadschia argus) broadcast spawning by raising itself above substrate and sending streams of sperm into water. East China Sea, Kagoshima Prefecture, Japan.

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. SEA CUCUMBER row from left: Pineapple sea cucumber (Thelenota ananas), Leopard sea cucumber (Bohadschia argus), Yellow sea cucumber (Colochirus...

Georgette Douwma / Composite image of echinoderms on black background. Species present: - Top row from left: Yellow sea cucumber (Colochirus robustus) and Lampert's sea cucumber (Synaptula lamperti), Black sea c...

Joel Sartore / Photo Ark / Florida sea cucumber (Holothuria floridana) close up moving its tube feet, Butterfly Pavillion. Captive.

Sergio Hanquet / Sea cucumber (Holothuria sanctori) aggregating on algae covered rock, Tenerife, Canary Islands.

David Fleetham / Parasitic Scale worm (Gastrolepidia clavigera) on a Blackspotted sea cucumber (Bohadschia graeffei) off the island of Yap, Federated States of Micronesia.

David Fleetham / Adult Graeff's Sea Cucumber (Pearsonothuria graeffei) feeding, Yap, Micronesia.

David Fleetham / Sea cucumber scale worm (Gastrolepidia clavigera) crawling on its host holothurian, the Black sea cucumber (Holothuria atra), Fiji.

Alex Mustard / Portrait of a large female Emperor shrimp (Zenopontonia rex/ Periclimenes imperator) on a sea cucumber (Bohadschia sp.). Dauin, Dauin Marine Protected Area, Dumaguete, Negros, Philippines. Bohol Sea,...

Sergio Hanquet / Sea cucumbers (Holothuria sanctori) Tenerife, Canary Islands.

Claudio Contreras / Impatient sea cucumber (Holothuria impatiens), Botella Point, Gulf of California (Sea of Cortez), Mexico, August

David Fleetham / Tigertail sea cucumber (Holothuria hilla), Hawaii.

Sergio Hanquet / Sea cucumber (Holothuria sanctori) Tenerife, Canary Islands.

David Fleetham / Sea cucumber (Holothuria sp). Pacific Ocean, Hawaii.

David Fleetham / Sea cucumber (Bohadschia argus) which has ejected a part of its internal organs called Cuvierian tubules. These significantly sticky strings are a defense mechanism designed to deter predators. Yap, M...

Francisco Marquez / Sea cucumber (Holothuria hylla) on white background, Islas Marias Archipelago, Marias Biosphere Reserve, Mexico.

Sirachai Arunrugstichai / Graeff's sea cucumbers (Bohadschia graeffei) extend their bodies to spawn on top of coral bommie, releasing gametes into the flowing current at Hin Daeng Pinnacle, Mu Koh Lanta National Park, Krabi Pr...

Sirachai Arunrugstichai / Graeff's sea cucumbers (Bohadschia graeffei) extend their bodies to spawn on top of coral bommie, releasing gametes into the flowing current at Hin Daeng Pinnacle, Mu Koh Lanta National Park, Krabi Pr...

Dimitris Poursanidis / Sea cucumber (Holothuria tubulosa) in seagrass meadow. Skyros, North Aegean, Greece.

David Fleetham / Graeff's sea cucumber (Pearsonothuria graeffei) showing the tentacles of this adult Holothurian feeding. Fiji.