How Do Starfish Get Away from Their Predators?

Starfish is a misnomer, since these marine creatures are not fish but echinoderms. Scientists now refer to them as sea stars, reports the "National Geographic." About 2,000 species of sea stars, relatives of sea urchins, exist. Because the most common varieties have five arms, the creatures are called stars. Their colors range from neutral brown shades to brights, like pink and orange. The smallest are 1 inch long, the largest about 2 feet.

  1. History

    • Now present in all the oceans of the world, starfish evolved about 600 million years ago in the Precambrian period, the earliest era of geological history, explains Earthlife. During that time, many single-celled organisms appeared. Members of the Echinodermata phylum did not develop their characteristic shapes till much later in their evolutionary history. Because of their bony, calcified skeletons, echinoderms have fossilized well, giving scientists a record of their evolution.

    Deterrents to Predators

    • Among the predators of sea stars are fish, including sharks; crustaceans, like crabs; birds; and humans, according to A-Z Animals. The animals pursue them for food. Humans collect them and dry their bodies to sell to tourists as souvenirs. Some traits of starfish, however, allow them to escape notice. Starfish are nocturnal, often sleeping under rocks all day. The ones with subdued coloring can camouflage themselves on the ocean floor, while those with the most striking colors can scare off potential predators, reports "National Geographic."

    Regeneration Abilities

    • Sea stars have a unique characteristic that permits them to regenerate a limb if they lose an arm. In fact, a few species can grow an entire new sea star from the severed appendage, as well, according to "National Geographic." This trait has proved to be their best defense against attackers. If the foe has one of the starfish's arms in its grip, then the echinoderm can drop it in order to escape.

    Threatened But Threatening

    • To maintain an ecological balance, enough sea stars must escape potential predators, but their preying on other species must also be limited. According to A-Z Animals, starfish populations are being drastically cut, not so much due to predators, as to loss of habitat and ocean pollution. On the other hand, sea stars, which each may eat more than a dozen clams or oysters a day, are doing serious damage to commercial beds in some places. The crown-of-thorns starfish, in particular, has devastated the world's coral reefs, most notably the Great Barrier Reef off Australia, reports Earthlife.