Sergio Hanquet / Arrow crab (Sternorhynchus lanceolatus). Tenerife, Canary Islands.

Juergen Freund / Arrow crab on sponge (Stenorhynchus seticornis) Caribbean

Juergen Freund / Arrow crab on brain coral {Stenorhynchus seticornis} Caribbean Sea, Cuba

Sergio Hanquet / Arrow crab (Sternorhynchus lanceolatus) portrait. Tenerife, Canary Islands.

Sergio Hanquet / Arrow crab (Sternorhynchus lanceolatus), close up. Tenerife, Canary Islands.

Graham Eaton / Yellowline Arrow Crab (Stenorhynchus seticomis) in an Azure Vase Sponge (Callyspongia plicifera). St Lucia, West Indies, July.

Chris Newbert / Arrow Crab (Stenorhynchus seticornis) in Anemone (Heteractis sp) 60 feet deep, Caribbean

Norbert Wu / Arrow Crab (Stenorhynchus seticornis) long spindly arms around central arrow-shaped body, Caribbean

Juergen Freund / Arrow crab (Stenorhynchus seticornis) on fan coral. Caribbean

Roberto Rinaldi / Arrow crab (Stenorhynchus setircornis), Belize

Roberto Rinaldi / Arrow crab (Stenorhynchus setircornis), Belize.

Angelo Giampiccolo / Arrow crab (Stenorhynchus seticornis) on tube sponge at night, Belize Cayes, Caribbean.