chaete

Chaete are hair-like structures found on the surface of certain organisms, primarily in the phylum Chaetognatha and some species of annelids. The term "chaete" comes from the Greek word "chaite," meaning "hair." These structures serve various functions depending on the organism.

In chaetognaths, chaete are used for locomotion and feeding. They are typically arranged in rows along the body and can be moved independently to propel the animal through the water or to capture prey. Chaetognaths are small, marine organisms that resemble arrow worms.

In annelids, chaete are found on the body surface and are used for sensory functions. They are often referred to as setae and are involved in detecting environmental stimuli such as light, temperature, and chemical changes. Some annelids, like earthworms, use their setae to anchor themselves in the soil.

Chaete are not to be confused with cilia, which are shorter and more numerous, and are involved in movement and the transport of materials within cells. Unlike cilia, chaete are typically longer and fewer in number, and they are external to the organism's body.

The study of chaete is important in understanding the evolution of sensory and locomotive structures in various animal groups. They provide valuable insights into the diversity of life and the adaptations that have allowed different organisms to thrive in their respective environments.