The Natural Habitat of Crayfish

Crayfish are a type of crustacean that have a similar appearance to small lobsters. Because more than 500 different species of crayfish are found, their sizes can differ greatly: the largest crayfish in the world is the giant Tasmanian freshwater crayfish, which can grow to 400 mm long and weigh 3.6 kg. Crayfish habitats are very important to their survival, and human activities, such as fishing and land development, can have a negative effect on their population numbers.

  1. Identification

    • Crayfish can be identified by their distinctive claws and antennae. They look very similar to lobsters and, like lobsters, they are edible. However, they are smaller, with different species' sizes ranging from 30 mm in length to 400 mm. Different crayfish species also have different colorings. The Queensland red claw crayfish, found in Australia, has a distinctive red patch on its claws. Other species of crayfish can be brown, green, blue, red, black and white.

    Geography

    • Crayfish can be found all over the world. Most species are freshwater crustaceans, while a few can also survive in saltwater environments. Crayfish can live in any body of water that doesn't become cold enough to freeze. This includes streams, ponds, rivers, dams and swamps. According to ecological implementation specialists Southern Ecological Solutions, crayfish prefer water with high oxygen content. While some species prefer environments with very little sediment, others, such as the spiny freshwater crayfish, live in environments with lots of debris.

    Behavior

    • Although different species can be found in different bodies of water, the one trait that all crayfish share is the need to hide. They will use rock crevices, tree roots or vegetation to do so to escape predators. If no cover is available, the crayfish burrow. According to the Australian Museum, all crayfish have the ability to dig and some species, such as the Australian land crayfish, spend their entire lives living in a burrow, only coming out to feed.

    Diet

    • Crayfish forage for food on the stream or lake bed, feeding off plant debris and rotting matter that they find in their local habitat. However, they are called "opportunistic omnivores" since they will eat most food they find, including carrion. According to Southern Ecological Solutions, the white-clawed crayfish will feed on worms, fish and even other crayfish, especially those that have just molted and have not yet developed a hardened exoskeleton.

    Threats

    • Crayfish face threats from predators, fishing and human activity. Predators that coexist in their natural habitat include birds, fish and invertebrates such as dragonflies and larvae. Crayfish are a popular food around the world and, in some areas, fishing has greatly affected certain species. One of these, the white-clawed crayfish in the United Kingdom, is protected under the Wildlife and Countryside Act of 1981. Other factors, including activities such as dredging and water pollution, have also caused a decline in crayfish numbers.