Introduction to the Marine Mammals Mammal Any of various warm blooded vertebrate animals of the class Mammalia characterized by a covering of hair on the skin and in the female milk producing mammary glands for nourishing the young Marine Mammals o Have similar adaptations for the marine environment Body Size Streamlined Shape Insulation Dense fur or blubber Modified skeleton Shortening of appendages Loss of hind limbs Similar Physiological Adaptations For diving thermoregulation osmoregulation communication and orientation o Have similar habitat requirements Require the aquatic habitat for survival They can therefore be used as indicators of habitat degradation o Many have been exploited by humans to the point of near extinction o Three Orders Carnivora The mammalian carnivores includes cats and dogs Suborder Pinnipedia fin footed o Most marine of the Carnivora o Use fat and or fur for insulation o Deep divers o Must return to land in order to give birth o Family Otariidae Sea lions and fur seals The Eared Seals Hind flippers rotate under the body to permit walking or running on land Swim by using the large fore flippers Dense fur that consists of long coarse hairs and thick underfur in which air is trapped to promote insulation Tend to have a temperatue to subtropical distribution o Family Phocidae True Seals Lack ears sometimes called earless seals Unable to rotate the hind limbs forward under the body and therefore don t move well on land Swim by using the hind flippers Small pectoral flippers are used for steering Blubber is used for insulation Excellent diving abilities Phocids are relatively large compared to Otariids Phocids are found throughout the world s oceans o Family Odobenidae Walruses One species Odobenus rosmarus Large tusks Can rotate hind flippers under the body Use both front and hind flippers to swim No external ear Naked skin with only a few sparse hairs Other Marine Carnivora o Family Ursidae Polar Bears Found only in the Arctic o Family Mustelidae Otters Sea otters of the pacific coast of N America and Russia Marine Otter of Chile and Peru Extremely dense fur Flattened hind feet for propulsion in water Axillary flap of skin to hold or store food and tools Horizontally flattened tail Cetacea Whales dolphins and porpoises Evolved from ariodactyls even toed ungulates such as cows or pigs All are large ranging from 2m to 30m Streamlined body form with minimal protuberances that could cause drag o Ex They all lack external ears reproductive organs appendages and are generally hairless Vestiges of the pelvic girdle Some have hair during fetal development Elongated skull with overlapping bones Dorsal positioning of the blowhole Subdermal blubber that can be 10 s of centimeters thick Porous oil filled bones Multiple stomach compartments 78 living species in two suborders o Mysticeti baleen whales Have baleen a keratin based brushlike adaptation suspended from the upper jaw Dorsally symmetrical skull Two blowholes Non fused mandible Tend to be large Smallest mystecete the Pygmy Right Whale is 6m Family Balaenidae 4 Species N and S right Whale Bowhead and Pygmy Right Whale Extremely convex profile of upper surface of skull No dorsal fin No gular grooves Family Balaenopteridae 6 species Blue Fin Sei Bryde s Minke and Humpback Flat profile to skull Small triangular dorsal fin Numerous gular grooves run from the snout to umbilicus Family Eshrichtiidae 1 species Gray whale slightly convex profile to skull no dorsal fin aseries of Knuckles above the audal peduncle 2 4 short gular grooves benthic feeder o Odontoceti toothed whales Possess teeth in one or both jaws Dorsally asymmetrical skull A single blowhole Fused mandible Vary in size Some dolphins are 2m The sperm whale is 18m Family Physeteridae 3 Species Sperm whale Pygmy and Dwarf sperm whale Dorsal hump or small dorsal fin Large bulbous head with spermaceti organ Flukes notched Well developed conical teeth in lower jaw only fit into sockets in upper jaw Family Ziphiidae 18 species Beaked whales 2 gular grooves Small dorsal fin Slender rostrum beak Flukes not notched 1 2 pairs of teeth confined to lower jaw Family Monodontidae 3 Species Beluga Narwal and Irrawaddy Dolphin Generally no dorsal fin or small dorsal fin Head blunt no beak Flukes notched All cervical vertebrae free Family Platanistidae 5 Species River Dolphins Small dorsal fin Jaws form a long beak Flukes notched Many well developed conical teeth in both jaws Family Delphinidae 32 Species Dolphins including the Orca Large dorsal fin except right whale dolphin Jaws form a beak or head gibbose hump Flukes notched Well developed conical teeth in both jaws or in lower jaw only Family Phocoenidae 6 Species Dorsal fin large and triangular Head blunt no beak Well developed to poorly developed spatulate teeth in both jaws Sirenians Manatees and Dugongs Evolved from elephants and other subungulates Skin lacks hair Well developed vibrissae whiskers Well developed layer of fat Pectoral limbs modified as flippers Hind limbs absent Tail modified into flukes Ears absent Family Dugongidae o 1 Species Dugong dugon o Nails absent o Tail modified into notched flukes o Male and female approximately the same size Family Trichechidae o 3 Species of Manatee o Vestigial nails present o Tail modified into rounded paddle o Male and female approximately the same size