Presentation on theme: "Marine Mammals Approximately 200 million years ago, another group of air-breathing vertebrates, the mammals, evolved from now-extinct reptiles Phylum Chordata."— Presentation transcript:
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 – 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
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 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
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 Photographs are property of the Riverhead Foundation
Seals, Sea Lions, and Walrus Members of the order Pinnipedia are nearly exclusively marine Pinnipeds include: – 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
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 – 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
Sea lions and fur seals Sea lions and fur seals (eared pinnipeds; family Otariidae) have 15 representative species – Rotatable hind flippers – External ear flap – Long, flexible neck – No fur or claws on flippers
Seals Found in Long Island waters Harbor SealHarp Seal Gray Seal Hooded Seal Ringed Seal All photographs are property of the Riverhead Foundation
Sea Lions found in Long Island waters There are NO sea lions in the Atlantic Ocean, and therefore no sea lions on Long Island (except at local aquariums) http://www.atlantismarineworld.com/exhibit-outdoor-sealion.html X
Walrus Walrus (family Odobenidae) are large pinnipeds with a distinctive pair of tusks – Both male and female have tusks; can reach 1 meter in length! – Used for defense, and anchoring onto ice Strictly Arctic! Benthic-feeder; feeds primarily on clams
Sea Otters and Polar Bears Sea otters and polar bears are marine mammals belonging to order Carnivora The sea otter is the smallest marine mammal, which lacks a layer of blubber Instead, the sea otter has extremely dense fur, which traps air against the body for insulation – Hunted extensively for fur nearly to extinction
Sea Otters and Polar Bears Sea otters are found only in the Pacific Ocean, and have the densest fur of all animals Sea otters inhabit nearshore environments and dive to the sea floor to forage on mollusks, crustaceans and echinoderms (sea stars and urchins) – Must eat ~25-30% of their body weight per day
Polar Bear Polar bears are semi-aquatic mammals that spend a good deal of their life drifting on sea ice in the Arctic They feed primarily on seals, which they stalk at breathing holes World’s largest land carnivore Thick blubber; translucent fur, black skin! Threatened by the loss of Arctic sea ice!
The Truth about Christmas http://www.youtube.com/watch?v=dB3JLKfmq-M&feature=related Polar bears are found exclusively in the Northern Hemisphere Where are penguins found???
Manatees and Dugong Sirenians (order Sirenia) include the manatees and dugong Sirenians, also known as sea cows, have a pair of front flippers, but no rear limbs Swim with up-and-down strokes of their paddle- (manatee) or V- (dugong) shaped tails Closest land relative is the elephant!
Manatees and Dugong Sirenians are the only herbivorous marine mammals; feed on aquatic plants and algae Some species live in fresh and/or brackish water Inhabit temperate or subtropical waters Severely threatened by motor boat collisions, harmful algal blooms, pollution, and severe winters
Stellar’s Sea Cow (the sirenian you’ll never see) The Stellar Sea Cow was a large, herbivorous marine mammal formerly abundant in the North Pacific Described by naturalist Wilheim Stellar in 1741; hunted to extinction within 27 years of discovery! – 8 meters long – Fed on kelp – Did otter hunting play a role?