Is the word 'tentacles' only related to octopus or any animal?

Many animals are associated with tentacles. Yes, octopuses are too. Other animals having tentacles are Hydra, sea anemone, some species of snails, squids. Even a mammalian species found in the Northern parts of America, Condylura cristata (star-nosed mole) has tentacles around its nose.

So, tentacles are not only limited to octopus, but are seen in diverse forms across the animal kingdom.