A species of crayfish, also known as a crawfish or crawdad, is capable of reproducing without mating. These invasive female freshwater crustaceans have turned to cloning themselves, allowing the population of marbled crawfish to spread from a single aquarium in Germany to other parts of the world. Researchers believe the species will begin impacting local ecosystems as it continues to spread.
Female Marbled Crayfish Clone and Spread Rapidly
The marbled crawfish has only existed as a species for about 35 years. Its first known specimen appeared in 1995 in an aquarium in Germany. The first crayfish of this now all-female species was born with the ability to clone itself without having its eggs fertilized by a male. Every egg laid by a marbled crawfish is a clone of the mother.
The marbled species is a split from the slough crayfish native to the Florida Everglades. According to a genetic analysis, the marbled variety is the result of a mutation in the sex cells of the parents.
Aside from natural mutations, all marbled crawfish are genetically the same. Unlike most animals, which have two sets of chromosomes — one from each parent — this species has three sets.
Crawfish are popular aquarium pets because they can reproduce quickly. However, the problem comes when they are introduced into the wild. Their quick adaptability also means that they can spread very fast.
Since its creation in 1995, the marbled crawfish has spread to freshwater systems around the world, including Japan, Madagascar, Ukraine, and the United States.
The Crayfish, a Danger?
A recent study documenting this spread called the marbled crawfish potentially the most dangerous invasive crawfish species in Europe. A single specimen can easily become 300 within the span of three months.
While the news is a concern for environmentalists, cancer researchers hope to learn from the marbled crawfish’s abandonment of reproduction in favor of cloning. Because all specimens are genetically identical and reproduce by cloning themselves, the crawfish offers a model for an essential aspect of tumor development.
Tumor genomes in humans also come from a single cell and multiply by copying itself over and over. Both tumors and crawfish can still adapt to their environments by clonal evolution, which is a problem. With crawfish, this ability to change allows the species to spread to new climates. Tumors use this skill to develop resistance to treatments.
The best method to stop the spread of the crawfish is to prevent its introduction into the wild, as the species only travels through the pet trade. In the meantime, scientists hope the marbled crawfish’s reproduction strategy and genome will be useful in developing new cancer treatments.
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