Many people use the names crawfish, crawdad and crayfish interchangeably, but is that right? Are you getting your crustaceans correct? It's usually easy enough to identify a lobster, but crawfish, crawdads and crayfish come in a variety of sizes and colours, so it's no wonder people get confused.
What's the difference between crawfish, crawdad and crayfish?
What is a crayfish?
The name crayfish is primarily used to describe a freshwater crustacean that looks a little like a lobster, only smaller. However, some places use crayfish to describe saltwater species, too. Having crayfish in your waterways is usually a sign of clean water, as most crayfish can't live in polluted water.
Crayfish are omnivorous scavengers, and they can filter and process mud and can eat most foods. The white-clawed crayfish is the UK's only native crayfish, and is under threat from increasing droughts as well as invasive species - such as the American signal crayfish.
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Crayfish are crustaceans and invertebrates and shed their exoskeleton many times over the course of their lives. They have 10 legs - 2 at the front that are large claws - and are usually 5–15cm long. They are normally dark blue, dark green or black.
There are around 600 known species of crayfish and all of them have blue blood, due to a copper-based protein. They are also usually a keystone species, which means they play a central role in the structure of an ecosystem.
Is a crayfish a lobster?
Some people interchange lobsters and crayfish, but although they are closely related, they are not the same. Lobsters, which generally live on the seafloor, are significantly larger - measuring at around 20–50cm long. Lobsters can live for up to 100 years. Crayfish, however, live for 3–8 years.
What is a crawdad and crawfish?
In short, the answer to this question is: they are both the same as crayfish. These are common names used to describe what is essentially the same animal in different parts of the world. In the US state of Louisiana, people commonly call crayfish, crawfish – and it's Louisiana's official state crustacean.
Crawdad or crawfish are primarily used in central and southwestern American as a alternative name for crayfish.
Crayfish don't just have three names – they are also called baybugs, crabfish, craws, crawdaddies, freshwater lobsters, mountain lobsters, mudbugs, rock lobsters and yabbies.
When is a crayfish not a crayfish
There are places that describe certain crustaceans as crayfish, such as in Singapore, where the term crayfish tends to refer to Thenus orientalis, which is not a crayfish, but a crustacean from the slipper lobster family. In the UK, people may also refer to the European spiny lobster as a crayfish, or crawfish, but the only true native crayfish species is the white-clawed crayfish.
Threats to UK crayfish
The American signal crayfish was brought to the UK in the 1970s as a commercial species, but quickly escaped from fisheries, wreaking havoc on the native crayfish. They carry a disease that is deadly to white-clawed crayfish, and can also cause erosion along riverbanks.
