Alex Mustard / Commensal emperor shrimp (Periclimenes imperator) moves across the colourful red patterned surface of its host Candycane sea cucumber (Thelenota rubralineata). Misool, Raja Ampat, West Papua, Indonesi...

Juergen Freund / Timelapse of Giant sea cucumbers (Thelenota ananas) moving underwater, with a Giant clam (Tridacna gigas) in the background, Great Barrier Reef, Queensland, Australia, 2015.

Juergen Freund / Imperial / Emperor shrimp (Periclimenes imperator / Zenopontonia rex) on an Eyed / Leopard sea cucumber (Bohadschia argus). Lembeh Strait, North Sulawesi, Indonesia

Juergen Freund / Imperial / Emperor shrimp (Periclimenes imperator / Zenopontonia rex) on an Eyed / Leopard sea cucumber (Bohadschia argus). Lembeh Strait, North Sulawesi, Indonesia.

Juergen Freund / Imperial / Emperor shrimps (Periclimenes imperator / Zenopontonia rex) on a sea cucumber. Lembeh Strait, North Sulawesi, Indonesia.

David Shale / Underside of deepsea Sea cucumber (Deima validum) from 2500m, mid Atlantic ridge, June 2010

Jeff Rotman / Scarlet Psolus Sea Cucumber (Psolus fabricii), feeding with arm in mouth. Bay of Fundy, Canada, Atlantic Ocean.

Fred Bavendam / Leopard Sea Cucumber (Bohadschia argus) ejects a mass of long white sticky cuvierian tubules as a defense when disturbed, Manado, Indonesia

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

Tony Wu / Japanese sea cucumber (Apostichopus japonicus), rare albino. Hokkaido, Japan. May.

Georgette Douwma / Lampert's sea cucumber (Synaptia lamperti) group feeding, North Sulawesi, Indonesia.

Georgette Douwma / Candycane sea cucumber (Thelenota rubralineata). North Sulawesi, Indonesia.