crayfish

Crayfish, also known as crawfish or crawdads, are freshwater crustaceans in the order Astacidea, comprising the families Astacidae, Cambaridae, and Parastacidae. They inhabit streams, rivers, lakes, and wetlands, and some species dig burrows to endure dry periods.

Physically, they have a hard carapace, two large front claws, four pairs of walking legs, and a segmented abdomen ending in a tail fan. Their bodies are typically adapted to living in or near aquatic habitats, with gills for respiration and sensory organs that help them navigate murky water.

Crayfish are typically omnivorous scavengers, feeding on detritus, plants, algae, and small invertebrates, and they are often more active at night. They play an important role in freshwater ecosystems by breaking down organic matter and helping to cycle nutrients.

Reproduction involves mating after a molt; the male transfers a spermatophore to the female, who then carries eggs under the abdomen until they hatch into juvenile crayfish that resemble small adults. Juveniles molt repeatedly as they grow, gradually reaching sexual maturity.

Ecologically, crayfish contribute to nutrient cycling, sediment aeration, and serve as prey for many animals. Some species are invasive and can displace native crustaceans or damage vegetation. Crayfish are valued as food in many regions and are raised commercially, but habitat loss, disease such as crayfish plague, and invasive species threaten various populations.