amazing creatures

Sharks are old—they predate dinosaurs by about two hundred million years. But despite this distant past they are related to humans in unusual ways. We owe both the lever system in our jaws and small bones in our ear to our shark ancestors. Sharks have their own “Jesus,” too: in 2001, workers in an Omaha zoo discovered a baby shark that seemed to have appeared overnight in a tank full of young females, an occurrence repeated in other shark tanks across the country. By a last-resort evolutionary adaptation, female sharks, it turns out, are capable of parthenogenesis, or virgin births.
Madeleine Schwartz, from a 6/27/11 New Yorker Page-Turner post on Juliet Eliperin's Demon Fish.


The natural history is pretty amazing. Sharks are cartilaginous fishes (they have a skeleton made of cartilage, not bone) of the sub-class elasmobranchii, which also includes rays and skates. There are more than four hundred species, ranging from the dwarf lanternshark (about 15 cm) to the whale shark, the biggest fish in the sea (‘Max: possibly 1700-2100 cm’, according to my Princeton Field Guide to Sharks of the World). They are very, very old: fossilised species that lived 150 million years ago are almost identical to modern sharks. Sharks were swimming the seas before our continents took shape, while the dinosaurs were still around; Homo sapiens’s 200,000 years are, in the shark’s sight, but an evening gone. Until recently, we knew strikingly little about them. We’re still hazy about such basic matters as how long they live, but research has been revolutionised by genetic testing and electronics. Reports of miraculous ‘virgin births’ to female sharks isolated from males in aquariums, for instance, have recently been explained: genetic sampling shows that sharks are capable of parthenogenesis, or asexual reproduction, in cases where sexual reproduction isn’t possible.
Theo Tait, reviewing Eliperin's book for the LRB, vol. 34, no. 15.

My favorite fact cited in both pieces: Americans are 40 times more likely to be hospitalized for an encounter with a Christmas tree ornament than from a shark attack.