The smalltooth sawfish is an unusual fish that is native to subtropical and tropical waters in coastal parts of the Atlantic Ocean and the Mediterranean Sea. Growing to lengths of 25 feet (7.6 meters), they are quite massive, but they are also quite rare. In fact, they are critically endangered, and their populations are severely threatened. Because of their increasing rareness, many female smalltooth sawfish have been reproducing parthenogenetically, which means they have been giving birth without a male or any sort of fertilization. A virgin birth, so to speak.

Pristis_pectinata_-_Georgia_Aquarium_Jan_2006 - Photo by Diliff
Smalltooth sawfish. Photo by Diliff.

Smalltooth sawfish are the first and only fish known to participate in this behavior in the wild, although captive sharks in aquariums have been known to have virgin births. In a Florida estuary, about 3% of the sawfish are the result of parthenogenesis (virgin birth) because some female sawfish cannot find any males during the mating season.

Pristis_pectinata_juvenile - Photo by NOAA
Juvenile smalltooth sawfish. Photo by NOAA.

While the ability to have virgin births might seem beneficial to a critically endangered species, it is not. Since these female smalltooth sawfish are reproducing without any input from a male sawfish, their offspring are not receiving any new genes, and they are practically clones. As a result, the smalltooth sawfish suffers from diminished genetic diversity. Without diverse genes, entire populations of sawfish could be wiped out by a single disease.