Marine Mammals
• All marine mammals arose from land ancestors and have become adapted to a marine existence • Streamlined body shapes reduce drag • Limbs have been modified into flippers • Evolved means of retaining large quantities of oxygen to facilitate long dives • Concentrated (highly saline) urine
Crabeater seal
Weddell seal
Leopard seal
Crabeater seal
Sea lions and fur seals
• Sea lions and fur seals (eared pinnipeds; family Otariidae) have 15 representative species
Marine Mammals
• In the United States, marine mammals are protected by the Endangered Species Act of 1985 and the Marine Mammal Protection Act of 1972 • Prohibits the capture, harming and/or killing of any marine mammal
Harbor Seal
Harp Seal
Hooded Seal
Marine Mammals
• Like the marine reptiles and birds before them, several different types of land animals successfully invaded the ocean:
– Seals, sea lions, and the walrus (order Pinnipedia) – Sea otter and the polar bear (order Carnivora) – Manatees and dugongs (order Sirenia) – Whales, dolphins, and porpoises (order Cetacea) • 120 species altogether
Marine Mammals
• Approximately 200 million years ago, another group of air-breathing vertebrates, the mammals, evolved from now-extinct reptiles • Phylum Chordata – Subphylum Vertebrata • Class Mammalia
– Seals – Sea lions and fur seals – Walruses
Seals, Sea Lions, and Walrus
• Pinnipeds (“fin-footed”) evolved from a terrestrial carnivore • They are predators, feeding mainly on fish and squid • Streamlined bodies for swimming • Thick layer of fat, or blubber for insulation, food reserves, and buoyancy
Photographs are property of the Riverhead Foundation
Seals, Sea Lions, and Walrus
• Members of the order Pinnipedia are nearly exclusively marine • Pinnipeds include:
– Rear flippers cannot be moved forward – No external ear flap – Claws (and fur) on flippers – Short, robust neck
Photograph is property of the Riverhead Foundation
– Long overshadowed by the dinosaurs until ~65 million years ago
Class Mammalia
• All mammals share the following characteristics:
– Warm-blooded (endothermic and homeothermic) – Four-chambered heart – Fur or hair (not feathers) to retain heat – Mammary glands to produce milk for young
– Rotatable hind flippers – External ear flap – Long, flexible neck – No fur or clal
Seals Found in Long Island waters
Sea lions and fur seals vs. Seals
Sea lions and fur seals (Otariidae)
Seals (Phocidae)
Seals
• Seals (earless pinnipeds; family Phocidae) have 19 representative species