A tentacle is a flexible, elongated organ most commonly found in pairs. It is most commonly found in invertebrates and a few species of mammals. Some plants also have analogous structures similar to tentacles.
Tentacles are most notably found in cephalopods such as squids and octopuses. They are mostly used to provide lift force while swimming. The tentacles also help to ensnare prey or fend off predators. The giant deep-sea squid has two elongated tentacles that have swivelling hooks attached to the ends. These are used to latch on to prey and reel it in towards the central beak. Other structures which are considered as tentacles include the eyestalk on snails.
Most plants are autotrophic, meaning that they derive their energy from the sun. However, some plants become heterotrophic as the soil they live in has poor nutritive value. These heterotrophic plants usually consume insects and small vertebrates that stumble into their trapping mechanisms. Some carnivorous plants, such as the sundew have tentacles covered with sticky substances that can capture prey.
Some limbless amphibians such as the caecilians have a pair of tentacles on each side of its head. Scientists speculate that these are used for aiding their sense of smell and navigation. Another vertebrate that has structures anatomically resembling tentacles is the star-nosed mole. As the name implies, it has tentacles around its nose. These tentacles are always in constant motion, feeling the environment around it. The star nose is also quite conspicuous and are 22 tentacle-like projects. The tentacles function as a touch organ by helping the animal find its way inside a burrow and also find prey.
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