What are Chaetae?

Chaeta (plural: chaetae) is a term used in biology to describe a type of sensory organ found in some invertebrates, such as annelids (earthworms), mollusks, and echinoderms (starfish and sea urchins). Chaetae are small, thread-like structures that are typically found on the body surface or appendages of these animals.

Chaetae are thought to be sensory organs that help the animal detect touch, vibrations, and possibly chemical signals in its environment. They are often found in clusters on the body surface and can be sensitive to different types of stimuli, such as pressure, temperature, or chemicals. In some species, chaetae are also used for locomotion or feeding.

The word "chaeta" is derived from the Greek word "kheir," which means "hair," and refers to the hair-like appearance of these structures. Chaetae are a distinctive feature of many invertebrate animals and can be found in a wide range of species, from simple worms to complex sea stars.