Bluntnose Sixgill Shark - Reproduction

Reproduction

Very little is known about the reproductive process of bluntnose sixgill sharks. What little is known is actually scientific speculation. Many biologists believe that the male bluntnose sixgill shark's teeth are specially adapted to the courtship ritual. The male will nip at the female's gill slits using its longer-cusped teeth. This action is thought to entice the female into mating. Evidence of this hypothesis is that female bluntnose sixgill sharks show up with seasonal scars around their gill slits, which apparently is from breeding with males. The female bluntnose sixgill shark reaches sexual maturity between the ages of 18 and 35 years. Males usually reach sexual maturity much younger, between the ages of 11 and 14 years old. Scientists are unsure of how the bluntnose sixgill shark reproduces but it is thought that males and females meet seasonally between the months of May and November. The gestation period is unknown but scientists believe that it is longer than 2 years. The bluntnose sixgill shark is ovoviviparous, which means that the young are carried within the mother's body until the eggs hatch. They develop without a placenta to provide nourishment. The pups are born at a fairly large and developed stage at 65 to 74 cm. New pups are also born with a lighter belly than adults. This is a form of cryptic coloration or camouflage that is used to disguise the pup's appearance. The litter size ranges from 22 to 108 pups. It is presumed that there is a high mortality rate of the young pups, owing to the large litter size.