Did you know that the skin of the seal shark (Dalatias licha) has been made into an expensive leather called shagreen and used in Europe for book binding, sword hilts, luggage and jewelry since the 17th century?

The skin is dark brown (that’s why the seal shark is called Schokoladenhai -schokolade shark- in German) with small and flat dermal denticles. Reaching usually 4.6 ft -1.4 m – in length, the seal shark is with its large teeth and strong bite a powerful predator, but can also take bites out of larger prey, just like its little cousin, the cookiecutter shark (although its lips are not modified to be suctorial).

Dalatias licha head.jpg
Von asobi tsuchiyadeepseashark25, CC BY 2.0, Link

Like all sharks of the family kitefin sharks, the seal shark is a deep sea shark with a slow growth and small reproductive rates. Females give birth to 6 – 8 living young after a gestation period of two years. The embryos hatch inside one of the two functional uteruses (not divided into compartments) and are sustained by yolk (ovovivipary). In between pregnancies the females may have a year of rest. The young are born at a length of 12 to 18 in -30 to 45 cm- and mature at 2.53 to 3.97 ft – 77 to 121 cm- (males) and 3.84 to 5.22 ft – 117 to 159 cm – (females).

The seal shark (also known as kitefin shark) is caught commercially for its liver oil (especially its squalene) and skin (see above) as well as for meat (in Europe and Japan, but also Australia due to the relaxation of regulations regarding seafood mercury content) and fish meal, but also as bycatch in deepwater longline, bottom trawl and gillnet fisheries. Once discarded overboard, deepwater sharks rarely survive. This causes the seal shark to be considered Near Threatened globally and Endangered in European waters. Due to its habitat near the bottom of the sea the seal shark is no danger to humans, but bites occasionally into underwater fiberoptic cables.

Sources: here and here