ASK THE AQUARIUM: Are Arms and Tentacles the Same?
BY SHERRY WHITE
Special to The Pilot
Q. On TV shows about octopuses and squid, the narrator sometimes uses the word "arms" and at other times the word "tentacles." Are arms and tentacles the same thing?
A. Good question, and a tricky one. Although arms and tentacles are very similar, there are differences. The terms are often used interchangeably by mistake.
Scientists classify octopuses, squid, cuttlefish and nautiluses as cephalopods (sef-ah-la-pods). Generally speaking, arms have suckers running their full length. Tentacles usually have suckers only at the tips. Also, tentacles are usually longer than arms.
Octopuses, squid and cuttlefish all have eight arms. Cuttlefish and squid have eight arms and two tentacles. The seldom-seen, nocturnal chambered nautilus has 90-plus tentacles!
Both tentacles and arms vary in length, depending on the animal. How animals use these highly-adapted appendages also varies, depending on the species. The most common uses include locomotion, mating and capturing prey.
Jellyfish are totally unrelated to cephalopods, but also have tentacles, some of which can reach lengths up to 60 feet. Sea stars, commonly called starfish, are not related to cephalopods either, but they too have arms lined top to bottom with small, sucker-like cups called "feet." All that's another column.
The biology and habits of cephalopods are extremely interesting. Scientists consider them the most intelligent of all invertebrates, and experiments have demonstrated that they learn quickly. Scientific debate continues as to whether or not these animals can learn by observation.
For more information on the intriguing, intelligent creatures known as cephalopods, check out www.thecephalopod page.org/.
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, log onto www.ncaquariums.com, or call 800-832-FISH.
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