Why are starfish brightly colored

Tube feet also help the sea star hold its prey, including clams and mussels. Sea stars prey on bivalves like mussels and clams as well as small fish, snails, and barnacles. If you've ever tried to pry the shell of a clam or mussel open, you know how difficult it is. However, sea stars have a unique way of eating these creatures. A sea star's mouth is on its underside.

When it catches its food, the sea star will wrap its arms around the animal's shell and pull it open just slightly. Then it does something amazing: the sea star pushes its stomach through its mouth and into the bivalve's shell. It then digests the animal and slides its stomach back into its own body. This unique feeding mechanism allows the sea star to eat larger prey than it would otherwise be able to fit into its tiny mouth.

Many people are surprised to learn that starfish have eyes. It's true. The eyes are there—just not in the place you would expect. Sea stars have an eye spot at the end of each arm. This means that a five-armed sea star has five eyes, while the armed sun star has 40 eyes. Each sea star eye is very simple and looks like a red spot. It doesn't see much detail but it can sense light and dark, which is just enough for the environments the animals live in.

Starfish belong to the animal class Asteroidea. These echinoderms all have several arms arranged around a central disk. Asteroidea is the classification for "true stars. Male and female sea stars are hard to tell apart because they look identical.

While many animal species reproduce using only one method, sea stars are a little different. Sea stars can reproduce sexually. They do this by releasing sperm and eggs called gametes into the water. The sperm fertilizes the gametes and produces swimming larvae, which eventually settle on the ocean floor, growing into adult sea stars. Starfish succumb to predators such as large crabs, sharks, triggerfish and giant Triton snails.

Although it's unlikely your aquarium has these animals large enough to attack your starfish, it might have another major predator: other starfish. Large starfish can chase down -- slowly -- smaller starfish and attack them.

Prey starfish often detach an arm to escape, but it doesn't alway save them. Keeping your starfish well-fed can help keep them from attacking each other. The granulated sea star Choriaster granulatus has many nicknames: cushion sea star, doughboy star, big-plated sea star, and others pertaining to its characteristic plumpness.

The only species in the genus Choriaster , this uniquely puffy starfish is found in shallow waters on coral reefs and rubble slopes, where it feeds on algae, coral polyps, and dead animals.

The royal starfish Astropecten articulatus gets its name from its decadent purple and gold color. The vividly hued species is found along the east coast of North America, primarily in the Southeast.

While it can live at depths of up to feet, it mostly hangs out at around 70 to feet deep, where there are plenty of mollusks to eat. Unlike many other species of starfish, the royal starfish eats its prey whole. The fascinating bat sea star Asterina miniata is called so because of the webbing — resembling bat wings — between its arms.

While the species usually has five arms, it can have up to nine, and it can occur in a range of colors, including green, orange, and purple. The crown-of-thorns starfish Acanthaster planci is one of the largest sea stars in the world, and its upper surface is covered in spines hence the name. To satisfy its extraordinary appetite, it eats stony coral polyps in the subtropical waters where it lives. Where crown-of-thorns exist in small quantities, they help boost the biodiversity of coral reefs by preying on the fastest growing coral species.

But where their populations are high, they can wreak havoc on the reefs. Their population booms are due in part to fishing and collection of their natural predators, the humphead wrasse and triton snail.

Named for its red-orange color, the Pacific blood star Henricia leviuscula is common along the Pacific coast of North America, found at depths of more than 1, feet.

It's actually a very small, slender species — up to 10 inches in diameter — that feeds on sponges and bacteria. Its main predators are birds and humans. The order Brisingida comprises 70 or so deep sea-dwelling starfish species.

Residing at depths of to 19,plus feet below sea level, they are suspension feeders, which means they use their six to 16 spine-covered arms to filter water and capture food as it drifts by.

They resemble seaweed or coral more than they do traditional starfish. The sea star's mouth is located at the center of the underside of the creature's central disc, the area from which its arms radiate. The starfish has a cardiac stomach and a pyloric stomach. Some species of sea stars have the ability to protrude their cardiac stomach from their mouths to grab and digest their prey.

She's covered the New York Comic Con for NonProductive since and writes about everything from responsible pet ownership to comic books to the manner in which smart phones are changing the way people shop. By using the site, you agree to the uses of cookies and other technology as outlined in our Policy, and to our Terms of Use. Size Sea stars range from almost 5 inches to more than 9 inches in size. Color Sea stars can be sand- or neutral-colored, or brightly colored. Arms Sea stars with five arms are the most common type of sea star.