Appropriate time of year to think about sharks, right? What, you don’t think so? You will – at the end of our review of what makes them Terminators of the deep. First, their skeletons are cartilaginous instead of bone, yielding flexibility and energy efficiency. Jaws aren’t attached in back allowing for horrifyingly huge portions to be torn apart by an endless supply of sharp teeth.
Sharkskin is basically a corset of dermal teeth which not only is protective, but also has hydrodynamic properties. Sharks have an acute sense of smell. Most see well. They can hear us splashing on the beach from far away. Their Ampullae of Lorenzini detect the electromagnetic fields all living things produce helping to locate you even if you’re floating quietly in the dark.
Jeesh. Think that’s not enough? Consider aspects of their reproduction. First, males have two penises. Hmm, get me some of that shark fin soup. And, hallelujah, if there are no males around, the females can produce pups on their own!
It’s called parthenogenesis. Virgin birthed shark offspring are all females, but they can, and will, mate with males as a future opportunity might present itself. Switching back and forth is called heterogamy. Dang if sharks don’t have quite the bag of tricks.
Make you feel superfluous guys? Well, before going for the saltpeter, note that (some will disagree) it is not known to have occurred naturally in a mammal although it has been in many other animal groups.
Some species of bees and wasps have exhibited parthenogenesis. Some crustaceans, snails, flatworms, and wild turkeys too. Several species of reptiles can reproduce parthenogenetically including whiptails, geckos, rock lizards, and Komodo dragons. Interestingly, in order for the process to commence in some lizards, one female must sort of go through the motions with another to stimulate egg production.
At the cellular level the process varies considerably from one species to another and can involve either meiosis or mitosis. (The diagram above relates only to sharks) Some of the progeny thus produced will result in genetic identity with the mother and others will be unique. Like I’ve said, truth is stranger than fiction.