Alex Mustard / Red clingfish (Arcos rubiginosus) pair blend in with their host, a deepwater sea fan (Iciligorgia nodulifera) East End, Grand Cayman, Cayman Islands, British West Indies, Caribbean Sea.

Tim Laman / Close up of Tiger leech (Haemadipsa picta) on a leaf in tropical rainforest, waiting for passing victim. Borneo

Tim Laman / Close up of Tiger Leech (Haemadipsa picta) on a leaf in tropical rainforest, waiting for passing victim. Borneo

Juergen Freund / Flatworm {Platyhelmintha} Indo-pacific

Peter Scoones / Sabelled worm / fan worm (Sabellastarte indica) Red Sea

Juergen Freund / Bristleworm feeds on coral {Polychaeta} Caribbean sea

Angelo Giampiccolo / European fan worm (Sabella spallanzanii) at night off Ponza Island, Italy.

Roberto Rinaldi / Tube worm (Spirographis spallanzanii), Egadi Island, near Sicily, Italy.