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Perfect Predators
Sea stars are eating machines that have gobbled up entire populations of marine animals. Long Island Sound oysters disappeared during the early 1960s after several years of sea-star feasting. Sea stars grab both sides of oysters with the suction cups on their arms and pry the animals open. The stars push their stomach out of their bodies through a small, central opening and insert it into their victim's shell, where they start digesting the animal. Sea stars finish their meals by sucking up their prey and passing it to a second, internal stomach.
A New Sea Star Species
A research team working with the National Science Foundation's Tree of Life Project have found that xylopax, a small, white disc-shaped animal about the size of a quarter, is a sea star that lost its rays through a process of natural selection. As sea stars mature, their rays grow from their centers. Xylopax kept a circular, juvenile form to enhance their survival. Without arms, they are better able to slither into scraps of wood from shipwrecks littered along the ocean floor where they feed on microbes and hide from predators.
Crown-of-thorn Sea Stars
Crown-of-thorn sea stars were named for the short, sharp predator-proof spikes that cover their bodies. The species travel in packs, settling in reefs and feeding on the live adult coral. One crown-of-thorn sea star can destroy roughly 65 square feet of coral a year. Coastal communities have tried to protect reefs by eradicating the sea stars. Originally, divers worked their way through the coral stabbing and cutting up the predator. However, like other sea stars, crown-of-thorns can regenerate new bodies from a single arm, and cutting up the sea stars only increased their numbers.
Sea Star Slime
The cushion sea star, a puffy, five-armed star found along the northern pacific coast, is one of several species that release a wave of thick mucus to protect themselves. The slime not only makes it difficult to capture the animal; it has a bad taste that discourages predators looking for feed. Spiny sea stars that live off the coast of Scotland generate a coat of slime to protect themselves from bacteria and other irritants. Scientists believe spiny sea star slime might lead to treatments from asthma, arthritis and gout in humans.