The All-Female Crayfish Species

Written by Science

Crayfish, sometimes also known as crawfish, crawdad or freshwater lobsters, are closely related to the lobster. Crayfish can be found throughout the world, mainly in freshwater. These freshwater crustaceans are mainly used as food globally and a quick search on Google will return you with various ideas of how you can prepare a crayfish dish. Apart from that, crayfish are also being used as bait for fishing or kept as pets in freshwater aquariums.

Recently, a study has reported that marbled crayfish, a mutant species of all-female crayfish, are upsetting the ecosystem due to their ability to self-clone (reproduce by themselves) rapidly. But where do these mutant crayfish originate?

Genome sequencing of a few marbled crayfish from various locations suggests that all of them are of the same origin. The common ancestor of these self-cloning mutant crayfish is a female slough crayfish born in the aquarium of a German pet shop in 1995. Unlike normal crayfish, this particular female had an additional set of chromosomes that gave her (and her offspring) the ability to reproduce asexually (to lay hundreds of eggs at a time without mating) as well as the ability to survive changes in environmental conditions.

Taking only two to 20 weeks for the eggs to hatch (depending on the water temperature), these crayfish are indeed very useful to be used as a cheap source of protein in poverty-stricken countries. Besides that, in Germany, scientists are actually using crayfish as tumour models to aid understanding on how tumours can adapt and develop resistance to drug treatments.

This reproductive behaviour of crayfish has created an ecological nightmare

However, this rapid, high-volume reproductive behaviour of mutant marbled crayfish has also created an ecological nightmare, as they are threats to the native freshwater crayfish species in the habitats invaded by them. This is particularly problematic in Madagascar with the population of marbled crayfish estimated to be in the millions.

In fact, knowing the problem posed by the marbled crayfish, the European Union and a few American states have already banned the ownership or trading of said crayfish. It is also illegal for anyone to release any unwanted crayfish into the wild.

If you are interested in reading more about another similar story, then why not check out the ‘Amazon molly’. This freshwater fish reproduces asexually-ish, in that females must mate with a male, but their eggs do not take any genetic material from the ‘father’ (a process called gynogenesis by the science community).

Last modified: 28th February 2018

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