Question: what have you learned about crayfish in your research

Zara Gladman answered on 15 Jun 2011:

A good question 🙂

Since starting my PhD, I have learned that….

– Crayfish eat a huge range of things… from little invertebrate bugs in the riverbed, to plants and small fish… they’re also cannibals and eat each other!

– Crayfish can compete with other animals including fish. They compete with young salmon for food and shelter, for example. This means that the salmon are forced to swim in the open water away from shelter… forcing them to use up energy reserves and making them more vulnerable to predation.

– Crayfish are most active at night. When I peer into my crayfish tanks during the day, they’re usually sitting around doing nothing. I set up video cameras to record them during the night, and I was amazed at how active they are in darkness! Crayfish are nocturnal and so look for food when it’s dark.

– Crayfish move very large distances! I tracked crayfish in a river and found that they moved a few hundred metres in just a couple of days. A few animals in Loch Ken moved over a quarter of a mile in a couple of weeks. Pretty impressive for such a small animal!

– Crayfish can survive out of water for a long time… they can also walk on land quite easily.

– Once crayfish are introduced to a river, pond or lake, it is VERY difficult to get rid of them! One summer, some fishermen and scientists decided to trap as many crayfish as they could from Loch Ken, which has a massive population of crayfish. They removed OVER A MILLION animals! But at the end of the trapping, there was still an enormous population.

Finally, I have learned that when a crayfish manages to grab you with its claw… it is VERY PAINFUL!!! :-O