Teacher Resources

Star fish, sea star, star fish, sea star. What is the difference? The answer is quite simple-there is no difference. The star fish and sea star are one in the same. Star fish is is just a nickname for the sea star. Sea stars belong to a group of echinoderms, which includes sea urchins, sea cucumbers, brittle stars, and sea lilies. There are about 1,500 species of sea stars found only in the marine environment and they are abundant at all depths of the ocean.

Sea stars are fascinating to observe because they are invertebrate animals. They have no head, no front end, and can move in any direction. One amazing fact about sea stars is that along with no head, they lack an important feature that most people would find to be standard and that is a brain. They range in size between 0.4 inches to 2 feet across.

Sea stars are some of the most unusual creatures you can find in a tide pool. They come in a variety of colors-orange, green, purple, blue, brown, red, yellow, or even multi-colored. One of the most remarkable features of sea stars is their ability to regenerate damaged or lost body parts. Generally sea stars are stiff bodied and crawl slowly. When moving around, they can reach a top speed of twenty inches per minute. Sea stars have four to six arms, but five is the most usual. Some sea star species even have up to forty arms.

If you ever picked up a sea star and turned it over, you probably noticed the hundreds of tube feet lining its arms used for crawling, feeding, and attachment. The skin is rough, leathery, and usually has spines. Sea stars have moderately well developed senses of touch, smell, taste, and respond to light. On the end of each arm is a small pigment eye spot that is sensitive to light. Some sea stars are drawn to light, while others would rather stay in darkness.

Sea stars feed on a wide range of items, including ocean-bottom deposits. They can eat small animals whole and deal with larger prey by using the outside of their bodies. Sea stars play an important role in some animal communities because they eat a variety of materials, such as bacteria. Finally, under some conditions, sea stars can do some harm-a few are pests to oyster beds, and some species of sea stars feed on coral reefs.