Author’s Note: We won’t be getting into the nitty gritty of the male/female reproductive systems as they are fairly complicated (and not our area of expertise). However, if you have further questions about their reproductive systems and the many body structures involved, we will gladly direct you to a more qualified scientist to answer.
Depending the shark, skate, ray or chimaera, not much is known about their mating. A few sharks and rays have been caught in the act (see these displays here, here, here), but scientists are still searching for answers. There are a few generalizations we can make:
First, fertilization in all Chondrichthyans is internal, unlike fish who disperse their eggs and sperm into the water. While that allows for a larger number of young to be born (and at a quicker rate), internal fertilization results in a higher chance of survival.
This internal fertilization requires a male to mate with a female, with most of the decision being left up to the female to choose her mate. Like humans, male sharks have paired testes that are symmetrical. With these paired testes come two claspers to aid with mating. Claspers are tube-like organs that help transport the sperm from the male shark into the female shark. They start off being small and flexible, hardening through calcification and growing as the shark matures. A male will insert the clasper (some may use just one clasper while others may use both and either insert them one at a time or at the same time) by where he has grasped a female with its teeth. This means that if he has gripped her left pectoral fin, he will use the left clasper.
Shark mating is anything but lovey-dovey. On top of the female being held by the male shark by his teeth (either on a pectoral fin or on her body), the clasper is held in place inside the female by a sharp spur. Don’t worry, though these bites often times leave wounds and scars, these bites are less powerful than feeding bites. Some sharks have got thicker skin to help mitigate the damage done by their partners.
Once in a good enough position, the male will release spermatophores from the storage chambers into his cloaca where they pass into the clasper. The male will contract his siphon sacs to help move the spermatophores along the clasper into the female’s cloaca to pass into the oviducts. A current of seawater also aids in this process, as well as possibly help eliminate other male gametes.
Females can mate with more than one male, allowing for their litter to be fathered by multiple males (more on that in the post “Different types of reproduction in Chondrichthyans”) or to store the sperm for future use.
From here, there are three different reproduction methods a Chondrichthyan can follow.
do you have any questions? feel free to ask us in the comments below!
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TFUI Founder Melissa C. Marquez is author of all animal bios and "Behind the Fins" segments.
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