Cirri are slender, hair-like structures found in various organisms, including some species of marine invertebrates and plants. In marine biology, cirri often serve as sensory organs or feeding appendages, helping creatures like barnacles and sea cucumbers interact with their environment. In botany, cirri can refer to tendril-like structures that help climbing plants attach to supports. These adaptations allow plants to reach sunlight and grow more effectively in their habitats. Overall, cirri play important roles in the survival and functionality of the organisms that possess them.