Season's Greetings from the Barbados Fisheries Division! Christmas is a day where many of us celebrate the birth of Jesus Christ - a birth described as a miracle, and quite out of the ordinary; that is, for humans at least. In the natural world, there are many examples of virgin births within bony fishes, amphibians, reptiles and birds, where females are able to produce offspring from unfertilized eggs; a strategy formally know as parthenogenesis. Below are two species, found within Barbados' waters, which have this capability!

2007-2008 was a busy period for Demian Chapman, who was at the time based at the Guy Harvey Research Institute, Oceanographic Centre, Nova Southeastern University, Florida. He spent time researching parthenogenesis in two species: the bonnet hammerhead shark (Sphyrna tiburo), and the blacktip shark (Carcharhinus limbatus), being the first to provide definitive evidence of the process in cartilaginous fishes.

Blacktip Shark (left) (photo credit: Seattle Aquarium) and the Bonnet Hammerhead Shark (right) (photo credit: Robertson Ross).

In both instances, genetic analysis of tissue samples from captive bonnet hammerhead and blacktip sharks who had given birth was conducted. the three hammerhead sharks studied were captive and isolated from males for three years, while the blacktip shark had no contact with male members of its species for eight years, but did live in the same tank as a male sandbar shark. In both cases, however, genetic analysis revealed that the offspring produced had no paternal genes, being genetically identical to the mothers. It is hypothesized that this strategy was most likely employed for survival in the absence of eligible mates.

While baby Jesus may not have been genetically identical to his mother Mary, his birth, to a virgin mother, left many in shock! We hope you enjoyed reading about these interesting marine births.

Merry Christmas from the Barbados Fisheries Division, and a Happy New Year!

References:

Chapman et al. (2007) Virgin birth in a hammerhead shark. (doi: 10.1098/rsbl.2007.0189)

Chapman et al. (2008) Parthenogenesis in a large‐bodied requiem shark, the blacktip Carcharhinus limbatus (DOI:10.1111/j.1095-8649.2008.02018.x)

Cover photo credit: eatlife.net