The Greenland shark, Somniosus microcephalus, is also called the sleeper shark and the gurry shark. This large, slow-swimming shark has glow-in-the-dark eyes. It lives in very deep waters of the North Atlantic Ocean. It lives at depths down to 1,800 feet (550 m) in very cold water (36 to 45°F=2 to 7°C).

These sharks swim to shallow Arctic waters (up to 80° North) during the winter to eat (they gather in large numbers to feed around fishing and sealing operations). They migrate back to deep waters during the summer. Eskimo hunters traditionally used this shark's skin for boots and its teeth for knives.

Anatomy: The Greenland shark is up to 21 feet (6.5 m) long. This grayish-brown shark has a short snout and small fins. Bioluminescent (glowing) copepods attach to the Greenland shark's corneas (a part of the eyes). This may attract curious prey to the shark's head! The shark's upper teeth are long and sharp; the lower teeth are flatter, more closely-set (and also sharp).

Diet: The Greenland shark eats fish (like salmon), dead cetaceans (whales), and pinnipeds (like seals and sea lions).

Reproduction: This large shark reproduces via aplacental viviparity, having litters of about 10 pups, each roughly 15 inches (38 cm) long. In aplacental viviparity, the eggs hatch and the babies develop inside the female's body but there is no placenta to nourish the pups.

Classification: Kingdom Animalia, Phylum Chordata, Class Chondrichthyes, Order Squaliformes, Family Squalidae (dogfish sharks).