In the world full of concern about endangered animals, the mutant crayfish are in the totally opposite state. These mutant crayfish, called marmorkrebs (or marbled crayfish), are spreading all over the world – from a stream in Florida to Madagascar.
Then, why are the people calling them the “mutant” crayfish? The reason is that the number of the marmorkrebs with the same copies of chromosomes is increasing. In other words, they are being “clones” for each other!!!
Indeed, there is one distinct feature of marmorkrebs which let them make their offspring as their clones. It is “PARTHENOGENESIS”. In parthenogenesis, the female marmorkrebs are able to fertilize themselves and lay their eggs without the assist of male marmorkrebs. Despite the fact that common animals’ chromosomes are comprised of the chromosomes both from their mom and dad, marmorkrebs, which show parthenogenesis, does not. To be specific, common animals has two sets of chromosomes, one from their mom and the other from dad. However, marmorkrebs get all of those two from their mom!! Then, does it mean that males do not have any role?
No, it’s not. Here is the case. If a female produces an egg with two sets of chromosomes and a male fertilize it, a third chromosome is added to it, making these offspring to have three sets of chromosomes. Then, what makes these offspring special is that an extra copy of the gene can remove damaged genes from the marmorkrebs’ genomes!
However, as these species are becoming popular as pets, they lack the chance to make three chromosomes. The female-produced eggs hatch without the males’ fertilization. If one of the female marmorkrebs escapes from one’s house and enters a stream, then the result will be awful – a stream full of clones. One final problem is that they are going to invade the native species in the new environment.
For this problem of rapidly spreading species, ecologists are still working hard for the remedy.