Everything about Tentacles totally explained
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're used for feeding, feeling and grasping. Anatomically, they work like other
muscular hydrostats.
Tentacles in marine animals
The phylum
mollusca includes many species with
muscular hydrostats in the form of tentacles and arms (
octopuses don't have tentacles: they've arms). Tentacles are longer than arms and usually have suckers at their tips only.
Squid and
cuttlefish have eight arms like octopuses, and also two tentacles, which is one good way to distinguish squid from octopuses.
The tentacles of the
Giant Squid and
Colossal Squid are particularly formidable, having powerful suckers and deadly
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 thick, sharp, finger-length screws of protruding bone.
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
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're 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.
Tentacles in cultural context
The great differences between humans and the tentacle-bearing
mollusca have led to tentacles being associated with inhumanity and disgust in legend and fiction. For examples, see:
Further Information
Get more info on 'Tentacles'.
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