Animals That Don't Have a Male for Reproduction

Virgin female hammerhead and blacktip sharks have both been documented as producing young, much to the surprise of the scientific community. Little is known about the process by which these sharks are able to reproduce, but an emerging consensus suggests that sharks are evolving to use parthenogenesis, a process in which female eggs self-fertilize, when populations dip. In both recorded cases, no males were present when the captive female sharks became pregnant.

Jellyfish, sea anemones and flatworms all use a process called budding to reproduce. This complex process of reproduction, most commonly associated with strawberries, sees the parent produce cloned cells of itself, which eventually break away and grow into exact replicas of that parent. However, females who use budding as a means of reproduction are also capable of sexual reproduction.

Greenflies, stick insects, aphids, water fleas, scorpions, termites and honey bees are all capable of reproducing without males, using parthenogenesis. In the case of the honey bee, the use of parthenogenesis has evolutionary benefits, as they elect to use parthenogenesis when the local population requires more workers, or more queens.

The boa constrictor, monitor lizard and Komodo dragon are both capable of becoming pregnant without male fertilization, by parthenogenesis. This form of reproduction is not the preferred method and has evolutionary disadvantages for the species, as it constitutes a form of inbreeding that reduces genetic diversity. Whiptail lizards however, have evolved to a point where no males exist. This all-girl species relies entirely on parthenogenesis.

Chickens and turkeys can use parthenogenesis to fertilize their eggs. However, unlike reptiles, avian parthenogenesis has evolutionary benefits. It is most typically observed in younger hens, who have lower levels of age-related genetic damage and can therefore produce more viable young. Birds also produce nonidentical replicas, so genetic diversity is wider in populations conceived by parthenogenesis.