Refers to the sensory appendages of insects, crustaceans, and other arthropods. In everyday Japanese, 触角 is the standard zoological term.
A rhinoceros beetle's antennae are very sensitive.
Ants communicate with each other using their antennae.
触覚 means the sense of touch, while 触角 (same reading) refers to an insect's antenna or feeler—easy to mix up in writing despite the unrelated meanings.
触手 refers to the flexible, soft tentacles of animals like octopuses or sea anemones, while 触角 refers to the sensory antennae of insects and crustaceans.
Standard kanji spelling for antenna/feeler.
Compound of 触 (touch, feel) and 角 (horn). The reading しょっかく is the on'yomi of both characters, with gemination (促音) of the first character's final く.