What is an "antenna"?

An antenna is an appendage attached to the head of some animals, including insects, crustaceans, and some mollusks. They are primarily sensory structures used for detecting touch, smell, and taste. The antennae are composed of a series of segments called antennomeres, which are connected by flexible joints. The shape and size of antennae can vary widely between different species, with some being thin and elongated while others are short and stout. Antennae can also be modified for specific purposes, such as for use as weapons, or for attracting mates through pheromones. In insects, the antennae are also important for flight, as they help to stabilize the insect's orientation and sense changes in wind speed and direction. Overall, the structure and function of antennae vary greatly across different animal groups, but they are an important sensory organ for many organisms.