Tentacle


Tentacle

Tentacles can refer to the elongated flexible organs that are present in some animals, especially invertebrates, and sometimes to the hairs of the leaves of some insectivorous plants. Usually, they are used for feeding, feeling and grasping. Anatomically, they work like other muscular hydrostats.

Tentacles in invertebrates

The phylum Mollusca includes many species with muscular hydrostats in the form of tentacles and arms (octopuses do not have tentacles: they have arms). Tentacles are longer than arms and usually have suckers at their tips only. Squid and cuttlefish have eight arms like octopuses, but also two tentacles.

The tentacles of the Giant Squid and Colossal Squid are particularly formidable, having powerful suckers and pointed teeth at the ends of the tentacle. The teeth of the Giant Squid are small, "bottle cap"-shaped circular saws, while the tentacles of the Colossal Squid wield two long rows of swivelling and three-pointed hooks.

Snails are another class of Mollusca. They have far less elaborate tentacles than the Cephalopods. Pulmonate land snails usually have two sets of tentacles on the head: the upper pair have an eye at the end; the lower pair are for olfaction. Both pairs are fully retractable. Some marine snails such as the abalone and the top snails, Trochidae have numerous small tentacles around the edge of the mantle. These are known as pallial tentacles.

Cnidarians, which include among others the jellyfishes, are another phylum with many tentaculated specimens. Cnidarians often have huge numbers of cnidocytes on their tentacles. Cnidocytes are cells containing a coiled thread-like structure called a "nematocyst", which can be fired at potential prey.

Many species of the jellyfishlike ctenophores have two tentacles, while some have none. Their tentacles have adhesive structures called colloblasts or lasso cells. These cells burst open when prey comes in contact with the tentacle; sticky threads released from each of the colloblasts will then capture the food.

Bryozoa (Moss animals) are tiny creatures with a ring of tentacles surrounding the mouth.

Tentacles in amphibians

Some wormlike amphibians have tentacles. The caecilians have two tentacles at their heads, which are probably used for the olfactory sense.

Tentacles in mammals

The star-nosed mole, "Condylura cristata", possesses nasal tentacles which are mobile and extremely sensitive, helping the animal to find its way about the burrow and detect prey.

Tentacles in plants

In carnivorous plants, tentacles refer to the stalked glands of the upper surface of the leaves.

On a sundew plant, they are hairlike projections with a drop of nectar-like glue which attract insects. When an insect is captured, the tentacles bend inward and the leaf rolls together as shown in the picture. The tentacles then secrete digestive enzymes to dissolve and engulf the insect.

External links

* [http://www.cephbase.utmb.edu/TCP/faq/TCPfaq2b.cfm?ID=50 Difference between arms and tentacles]


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  • Tentacle — Ten ta*cle, n. [NL. tentaculum, from L. tentare to handle, feel: cf. F. tentacule. See {Tempt}.] (Zo[ o]l.) A more or less elongated process or organ, simple or branched, proceeding from the head or cephalic region of invertebrate animals, being… …   The Collaborative International Dictionary of English

  • tentacle — 1762, from Mod.L. tentaculum feeler, from L. tentare to feel, try (variant of temptare to feel, try, test ) + culum, diminutive suffix …   Etymology dictionary

  • tentacle — ► NOUN ▪ a long slender flexible appendage of an animal, used for grasping or moving about, or bearing sense organs. DERIVATIVES tentacled adjective tentacular adjective. ORIGIN Latin tentaculum, from temptare to feel, try …   English terms dictionary

  • tentacle — [ten′tə kəl] n. [ModL tentaculum < L tentare, to touch: see TENT2] 1. any of a variety of long, slender, flexible growths, as about the head or mouth of some invertebrate animals, used variously for grasping, feeling, moving, etc. 2. Bot. any… …   English World dictionary

  • tentacle — UK [ˈtentək(ə)l] / US noun [countable] Word forms tentacle : singular tentacle plural tentacles one of the long thin arms of an octopus that it uses for feeling things or for moving …   English dictionary

  • tentacle — noun Etymology: New Latin tentaculum, from Latin tentare to feel, touch more at tempt Date: circa 1762 1. any of various elongate flexible usually tactile or prehensile processes borne by animals and especially invertebrates chiefly on the head… …   New Collegiate Dictionary

  • tentacle — noun An elongated, boneless, flexible organ or limb of some animals, such as the octopus and squid. With one blow of the axe, Captain Nemo cut this formidable tentacle, that slid wriggling down the ladder …   Wiktionary

  • tentacle — n. 1 a long slender flexible appendage of an (esp. invertebrate) animal, used for feeling, grasping, or moving. 2 a thing used like a tentacle as a feeler etc. 3 Bot. a sensitive hair or filament. Derivatives: tentacled adj. (also in comb.).… …   Useful english dictionary

  • tentacle — 1) a short fleshy appendage, perhaps better termed cirrus 2) the illicium, q.v., of an anglerfish, incorrectly …   Dictionary of ichthyology

  • tentacle — n. [L. tentaculum, feeler] Any elongate flexible appendage usually near the mouth; tentacular adj …   Dictionary of invertebrate zoology


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