Underwater Oddities, Photos

A crab crawls on the red tentacles of a sea fan in Fiji waters. Sea fans, also known as gorgonians, catch plankton in their polyps, which microscopic zooxanthellae then turn into gorgonian food. Sea fans also provide shelter and camouflage for reef life.
Photograph by Tim Laman

Majestic in purple, a spotted cleaner shrimp in the waters off Bonaire Island in the Caribbean works hard for its customers. This cleaner shrimp (Periclimenes yucatanicus) associates with a sea anemone and attracts fish from which it cleans and eats detritus such as parasites and algae. Such a symbiotic relationship benefits both the shrimp and the fish.
Photograph by Paul Sutherland

This close-up of a colony of white-spotted ascidians (Pycnoclavella diminuta) in Indonesian waters resembles aliens ready to feed. Instead, these ascidians, or sea squirts, are filter-feeding animals with one siphon to pull in water and another to discharge it. Adults remain rooted to the same spot their entire lives.
Photograph by Tim Laman