Symbiosis & Anemonefish - Reef Life of the Andaman - Part 18

Some cardinalfishes are small and careful enough to hide amongst the spines of the crown of thorns starfish or the sea urchin, thereby using the defense of the host to protect themselves. This is known as a "commensal" relationship, whereby one partner in the relationship benefits while the other receives neither benefit nor harm. It's a similar strategy adopted by anemonefishes. They make their home in sea anemones, the perfect refuge from predators. Their skin has a special immunity from the anemone's stinging tentacles. Skunk clownfish tend to favor the magnificent sea anemone. Clark's anemonefish are not so particular and find their home amongst a number of species of sea anemone. This is a mutually-beneficial relationship. While the fish are protected, their feces provide food for the anemone and they help keep it free of parasites. They also chase away polyp eaters such as butterflyfishes, thereby defending the anemone as well as their own family. Some even attempt to chase off passing divers. Juvenile Clark's anemonefish are predominantly orange in color. Saddle anemonefish are not so prevalent and are commonly associated with bubble-tip anemones such as here at Richelieu Rock. Juveniles display a white stripe reminiscent of other adult species. Anyone who has seen the film "Finding Nemo" will already be familiar with ocellaris clownfish. They are normally found living amongst magnificent sea anemones. Typically an anemone hosts a dominant female matriarch and her male mate, as well as one or more juvenile anemonefish. When the female dies, the male transforms into a female and the highest ranking adolescent is promoted to be her mate. Due to abnormally warm sea conditions, this anemone has lost the symbiotic zooxanthellae that give it its color, and may or may not recover. Other types of fish have also evolved a resistance to the sea anemone's sting. Juvenile domino damsels are often seen around sea anemones. Competition with anemonefishes, as well as with each other, can be fierce and incessant. As adults they are one of the most aggressive fish on the reef, for their size, and become less reliant on anemones for protection. Another creature that uses the anemone to protect itself is the porcelain anemone crab. At the end of the crab's third maxillipeds is a fan of bristles known as "setae" which the crab holds against the current to filter plankton from the water. Any collected food is scraped into the mouth by smaller setae on the innermost maxillipeds. Tube anemones are often seen in isolation on the seabed. This tube anemone's stinging tentacles provide protection for a magnifcent shrimp, as well phoronid worms which cover the tube. A pair of whitecheek monocle bream pass by. Jellyfishes, of course, are well known for their sting and often attract hitchhikers such as small sardines. The small fishes remain in the vicinity of the jellyfish, sometimes for their whole lives. When attacked, they find protection under the jellyfish's bell or even right inside, past its stinging tentacles. These hitchhikers are sheltering in a crowned jellyfish. And this rhizostome jellyfish is harboring juvenile scad. Older scad change from hunted to hunter. The jellyfish's sting is no guarantee of its own survival. This Australian spotted jellyfish at Racha Yai comes under attack from a scrawled filefish.