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.

Shane Gross / Channel clinging crab (Mithrax spinosissimus) in a pond on Eleuthera Island, Bahamas.

Shane Gross / Channel clinging crab (Mithrax spinosissimus), Eleuthera, Bahamas.

Shane Gross / Channel clinging crab (Mithrax spinosissimus), Eleuthera, Bahamas.

Pete Oxford / Channel Clinging Crab (Mithrax spinosissimus). Sian Ka'an Biosphere Reserve, Yucatan Peninsula, Mexico.

Shane Gross / Channel clinging crab (Mithrax spinosissimus) hiding under ledge, Eleuthera Island, Bahamas, North Atlantic Ocean.

Shane Gross / Channel clinging crab (Mithrax spinosissimus) hiding in cave, Eleuthera Island, Bahamas, North Atlantic Ocean.

Francisco Marquez / Moss-backed spider crab (Mithrax) on white background, Islas Marias Archipelago, Marias Biosphere Reserve, Mexico.