All-Female Fish Species

The "Amazon Molly" fish species, which is all female, has survived for 70,000 years without reproducing sexually, experts believe.

Scientists think the Amazon Molly may be employing special genetic survival "tricks" to avoid becoming extinct. The species, found in southeast Texas and northeast Mexico, interacts with males of other species to trigger its reproduction process. The offspring are clones of their mother and do not inherit any of the male's DNA.

Typically, when creatures reproduce asexually, harmful changes creep into their genes over many generations. The species will eventually have problems reproducing and can often fall victim to extinction. One theory for the Amazon Molly's continued existence is that the fish may occasionally be taking some of the DNA from the males that trigger reproduction, in order to refresh their gene pool.