Objectives: 1.Know the defining characteristics of mammals. 2.Classify different types of marine mammals 3.Relate physiological adaptation of marine mammals to their environment

vocabulary Mammary glands homeothermic Pinnipeds Sirenians Cetaceans Echolocation Baleen

Characteristics of Marine Mammals Mammary glands: special glands in the mother that provide young with milk. Placenta: a remarkable organ which is present only during pregnancy that nourishes the developing fetus. Hair.

Enhydra lutris: Sea Otter Order: Carnivora Found along the coast of California to the Aleutian islands of Alaska Seldom venture more than a mile off coast. Rarely come to shore except during storms, and perhaps to sleep. Nearly hunted to extinction in 1911 with only 1000 animals remaining. Now about 130,000 occupy 20% of their previous range.

Pinnapeds Includes: seals, sea lions, and walruses. All pinnapeds come to shore to give birth. Can be found in all waters, concentrated in the cold water Northern and southern hemispheres. Feed on fish and crustaceans. Except the leopard seal has been seen to eat penguins and other seals.

Pinnapeds

Evolutionary homology of Pinnaped locomotion diving and swimming Fast swimmers with speeds of mph. While diving metabolism slows by 20% to conserve oxygen. Blood is redistributed so brain and heart receive ample oxygen. the northern elephant seal can dive 4,125 feet. Flex the spine up and down for propulsion through water, similar to locomotion in terrestrial mammals.

Sirens: Manatees and Dugongs Both have vestigial pelvis with no hind limbs, and tail flukes. Dugongs are strictly marine, manatees can inhabit inland rivers and lakes. Strict vegetarians, guiding water plants to their mouths with their flippers. Greatest danger to manatees are propellers of motor boats.

Evolution of Whales

Cetaceans: Whales, dolphins, and porpoises Evolved from an ancient group of land- dwelling carnivorous mammals. Share embryonic homologies with mammals, such as hair, four limbs, flippers have 5 finger hand, and blow hole is located at the end of its head.

Adaptations for Diving Take in a large breath, oxygen is quickly exchange to blood, and then an exhale decrease buoyancy for the dive. Cetaceans have a larger amount of hemoglobin, and an even higher percentage of myoglobin (higher affinity for oxygen).

Cetacean Behaviors

Spy hopping: sticking their heads straight up to survey their surrounding. Breaching: when a whale completely or almost completely leaves the water. May be a way for whales to establish dominance, or other communication. Slapping: lifting their huge tails and slap them down on the surface. May associated with marking position or aggression.

Baleen whales Baleen whales: feed by filtering out plankton (especially krill), or fish. The Humpback sometimes capture their food by blowing a bubble net trapping prey at the surface. Examples of baleen include right whales, rorquals, and grey whales.

Toothed Whales

Include: Sperm whales, Orca, narwhal, dolphins, and porpoises. Sperm whales: unlike other species, they are aggressive! Rare and endangered species due to over harvest for spermaceti ( a high grade wax used for face cream, and lubricants.)

Porpoises and Dolphins Dolphins have a beak, Porpoises have a rounded head. Both feed on schooling fish. Bottlenose dolphin: Highly intelligent with self awareness. Have been observed helping others of their species to reach the surface to breath, and some confirmed stories of aiding injured or drowning humans.

Echolocation Use of sound to locate objects. Sounds produced by the animals larynx are focused by a structure called the melon. Echoes are picked up by the animals lower jaw and transmitted to the inner ear. They can determine the size and shape of objects.

Polar Bear Considered by some to be a marine mammal. Worlds largest land carnivore. Use sea ice to reach their prey of other marine mammals, mostly seals. Considered a vulnerable species, with most groups in decline, especially due to global warming and loss of sea ice.