Alex Mustard / Flamingo tongue (Cyphoma gibbosum) feeding on a seafan (Gorgonia ventalina) Cyphomas feed on corals and concentrate the toxic chemicals into their mantle, which they then wrap around the outside of it...

Alex Mustard / A common octopus (Octopus vulgaris) shelters between rocks. Gran Canaria, Canary Islands, Spain

Alex Mustard / Sea nettle jellyfish (Chrysaora quinquecirrha) with a small fish swimming alongside seeking shelter, West Palm Beach, Gulf Stream, Caribbean Sea, Florida, USA.

Alex Mustard / Bareye hermit crab (Dardanus fucosus) makes its home in a conch shell as it crawls over the sand, West Palm Beach, Gulf Stream, West Atlantic Ocean, Florida, USA.

Alex Mustard / Brown tube sponges (Agelas conifera) formation on reef wall with diver above, image taken with a circular fisheye, East End, Grand Cayman, Cayman Islands, British West Indies, Caribbean Sea.

Alex Mustard / A diver and dive boat visible through the canyons of a coral reef, East End, Grand Cayman, Cayman Islands, British West Indies, Caribbean Sea, January 2011.

Alex Mustard / Looking up at a dive boat over a shallow reef, East End, Grand Cayman, Cayman Islands, British West Indies, Caribbean Sea.

Alex Mustard / Red rope sponge (Amphimedon compressa) on coral reef wall with diver in background, High Rock Drop Off, East End, Grand Cayman, Cayman Islands, British West Indies, Caribbean Sea.

Alex Mustard / Stareye hermit crab (Dardanus venosus) in a canyon on a coral reef, East End, Grand Cayman, Cayman Islands, British West Indies, Caribbean Sea.

Alex Mustard / Turtle seagrass (Thalassia testudinum) a shallow seagrass meadow in a lagoon behind a coral reef, East End, Grand Cayman, Cayman Islands, British West Indies, Caribbean Sea.