Ask the Aquarium: The Truth About Sea Stars
Q. I heard if you cut up a starfish it will make new starfish. Is that true?
A. Yes, but please don't cut up a sea star to prove it!
If the arm of a sea star is severed but retains part of the body core, it can create an entirely new sea star. This amazing process is called regeneration. If a sea star loses only part of its arm, a new arm will begin growing within days.
Some sea star species even repopulate by breaking apart and slowly regenerating an entire body from a single arm. Although most sea stars have five arms, some have as many as 25 or 50, always in multiples of five.
Previously, sea stars were called starfish. They were renamed "sea stars" because they're echinoderms, not fish, and are related to sand dollars, sea urchins and sea cucumbers. Most North Carolina sea stars live around the subtidal zone or on the sandy seafloor of the continental shelf. Of more than 2,000 species known worldwide, 30 to 40 are found in North Carolina waters. The greatest variety is found south of Cape Hatteras, but only a few types commonly washed on shore.
One is the margined or purple sea star, Astropecten articulata. Another is the gray or slender sea star, Luidia clathrata. But by far the most familiar sea star found on our beaches is the Eastern or Forbes' sea star, Asterias forbesi, a chubby, burnt-orange to wine-colored specimen, with orange-yellow knobby skin and a conspicuous orange spot on top. The orange spot, called a madreporite, works like a sieve, straining sea water taken in by the sea star. When fully grown, the Eastern sea star can measure up to 6 inches across.
Sea stars are slow movers, using thousands of flexible tube feet on the underside of each arm to pull themselves over rocks or along the sea floor. They have no brain, just a simple nervous system, and all are predators. Some attack mollusks, some feed on dead fish, and others take in organisms from seawater.
These lovely but predacious animals can wreak havoc on oyster beds and other shellfish populations. Their mouths are on the underside of their body, and they have voracious appetites, eating almost constantly. Some species have been known to cause serious damage to coral reefs in parts of the world.
The state operates three public aquariums: one in Pine Knoll Shores, another at Fort Fisher and a third on Roanoke Island. The aquariums are administered by the North Carolina Department of Environment and Natural Resources, and are designed to inspire appreciation and conservation of North Carolina's aquatic environment.
For more information about the aquariums, visit www.ncaquariums.com, or call 800-832-FISH.
Sherry White works in the public affairs office for the N.C. Aquariums.
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