Alex Mustard / West Indian spider crab (Mithrax spinosissimus) shelter in a giant barrel sponge (Xestospongia muta) on a coral reef. Jardines de la Reina, Gardens of the Queen National Park, Cuba. Caribbean Sea.

Paul Harcourt Davies / Crab spider (Misumena vatia) with prey, Queen of Spain Fritillary (Issoria lathonia) near Orvieto, Umbria, Italy, July.

Alex Mustard / Sharpnose crab (Scyra acutifrons) male, crawling along the stipe of a Palm kelp (Eisenia arborea), Browning Pass, Vancouver Island, British Columbia, Canada, Queen Charlotte Strait, Pacific Ocean.

Alex Mustard / Maroon hermit crab (Pagurus hemphilli) with hitchhiking snails on its shell, portrait, Browning Pass, Vancouver Island, British Columbia, Canada, Queen Charlotte Strait, Pacific Ocean.

Alex Mustard / Pygmy rock crab (Cancer oregonensis) peering out from a hole in Yellow encrusting sponge (Myxilla lacunosa), Browning Pass, Vancouver Island, British Columbia, Canada, Queen Charlotte Strait, Pacific...

Alex Mustard / Sharpnose crab (Scyra acutifrons) hiding in a Purple sponge, Browning Pass, Vancouver Island, British Columbia, Canada, Queen Charlotte Strait, Pacific Ocean.

Alex Mustard / Sharpnose crab (Scyra acutifrons) feeding on passing particles, whilst hiding in a gap between a White short plumose anemone (Metridium senile) and a Yellow encrusting sponge (Myxilla lacunosa), Brown...

Alex Mustard / Spiny lithode crab (Acantholithodes hispidus) portrait, Browning Pass, Vancouver Island, British Columbia, Canada, Queen Charlotte Strait, Pacific Ocean.

Pascal Kobeh / Cuban rock iguanas (Cyclura nubila) and Caribbean hermit crabs (Coenobita clypeatus) on the beach with a Desmarest's hutia (Capromys pilorides), a species of rodent, in the background, Gardens of...

Pascal Kobeh / A Batwing or Queen crab (Carpilius corallinus) among corals, The Gardens of the Queen, Cuba, Caribbean Sea.

David Hall / The Umbrella crab (Crytptolithodes sitchensis) viewed from above, Queen Charlotte Strait, British Columbia, Canada. September.

David Hall / Umbrella Crab (Crytptolithodes sitchensis) portrait, Queen Charlotte Strait, British Columbia, Canada. September.

David Hall / Umbrella crab (Cryptolithodes sitchensis) resembling a discarded mollusc shell, Queen Charlotte Strait, British Columbia, Canada. October.

David Hall / Maroon hermit crabs (Pagurus hemphilli) in shells of Blue Topsnail (Calliostoma ligatum) Browning Pass, Queen Charlotte Strait, British Columbia, Canada. September.

David Hall / Helmet crab (Telmessus cheiragonus) and Hooded nudibranchs (Melibe leonina), Nigei Island, Queen Charlotte Strait, British Columbia, Canada. October.

David Hall / Greenmark hermit (Pagurus caurinus) Browning Pass, Queen Charlotte Strait, British Columbia, Canada. September.

David Hall / Rhinoceros crab (Rhinolithodes wosnessenskii) Queen Charlotte Strait, British Columbia, Canada. September, 2012.

David Hall / Spiny lithode crab (Acantholithodes hispidus) Queen Charlotte Strait, British Columbia, Canada. October.

David Hall / Hermit crab (Labidochirus splendescens) Slingsby Channel, Queen Charlotte Strait, British Columbia, Canada. September

David Hall / Pygmy rock crab (Cancer oregonensis) in the empty shell of a Giant Acorn Barnacle (Balanus nubilus). Browning Pass, Queen Charlotte Strait, British Columbia, Canada. September.

David Hall / Puget sound king crab (Lopholithodes mandtii) and Red sea urchins (Strongylocentrotus franciscanus), Deserter Group, Queen Charlotte Strait, British Columbia, Canada. September.

David Hall / Puget Sound king crab (Lopholithodes mandtii), Browning Pass, Queen Charlotte Strait, British Columbia, Canada. September.

David Hall / Northern kelp crab (Pugettia producta) large adult male is clinging to strands of bull kelp (Nereocystis luetkeana). Nigei Island, Queen Charlotte Strait, British Columbia. September.