Did you know that sharks are able to reproduce asexually? Genetic testing showed that the embryo did not arise out of storing sperm by the segregated female shark (as many are known to do) but from real parthenogenesis. One of them was a blacktip shark (another one a Zebra shark).

Kleiner Schwarzspitzenhai (Carcharhinus limbatus)
Blacktip shark, image by Albert Kok

Blacktip sharks (Carcharhinus limbatus) live in coastal tropical and subtropical waters all around the world, even in estuaries. They are fast and mostly hunt fish, but are also known to follow fishing boats and feed on their bycatch when discarded overboard. To protect their eyes from flailing prey they have got fully occlusible nictitating membranes.

Every other year female blacktip sharks return to their own nursery areas to give birth to four to seven pups. During the one year long pregnancy each embryo lives in its separate compartment (of the two uteri) – sustained at first by a yolk sac and later by placental connection. Due to predation and starvation the mortality rate of young blacktip sharks is high (up to 90%).

Blacktip sharks are up to 9.2 ft -2.8 m-  long and rather timid – except when captured or in the presence of food. They are responsible for 16% of the shark attacks around Florida (mostly resulting in only minor wounds, however). They are caught in large numbers by commercial fisheries for their meat, skin, liver oil and fins, and even more by recreational anglers (at least in the United States). All that caused the blacktip shark to become near threatened.

Sources: here, here and here

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