What is the structure of a tentacle?

A tentacle is unique in that “structure” is a word not often used in reference to this special aspect of biology. That is to say, tentacles are without a skeletal structure and are organs. Several species have tentacles, including squids, octopuses, snails, jellyfish, coral polyps, and even a mole (the star-nosed mole, to be precise). Tentacles are composed mainly of muscle tissue and are used for both movement and object manipulation (think here of an octopus escaping from a jar) as well as sensory perception (taste, smell, feel). The movement aspect and the sensory aspect of a tentacle varies based on the animal in question. In other words, some animals (e.g., the star-nosed mole) use their tentacle primarily for enhanced sensory perception, others use them primarily for movement and manipulation, and others have a combination of both at play.
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