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

– 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

Marine Mammals

– Have similar habitat requirements• Require the aquatic habitat for survival

– They can therefore be used as indicators of habitat degradation.

– Many have been exploited by humans to the point of near extinction

Types of Marine Mammals

– Three Orders• Carnivora- The mammalian carnivores, includes

cats and dogs – Suborder Pinnipedia (‘fin’-‘footed’)– Other Marine Carnivora

» Family Ursidae: Polar Bears» Family Mustelidae: Otters

• Cetacea- Whales dolphins and porpoises• Sirenians- Manatees and Dugongs

Marine Carnivora

• Suborder Pinnipedia (‘fin’-‘footed’)– Most marine of the Carnivora– Use fat and/or fur for insulation– Deep divers– Must return to land in order to give birth– Ex: Seals, Sea lions and walruses

Sea Lions

• 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 temperate-to-subtropical distribution

Sea Lions

True Seals• 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

Seals

Walrus

• 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

Walrus

Other Marine Carnivora

– Family Ursidae• Polar Bears

– Found only in the Arctic

Other Marine Carnivora

• 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

Sea Otters

Cetaceans

• Cetacea- Whales dolphins and porpoises– All are large, ranging from 2m to >30m– Streamlined body form with minimal protuberances

that could cause drag• 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

Cetacean Evolution

• Evolved from ariodactyls, even-toed ungulates such as cows or pigs– Multiple stomach compartments

• Like cows

Two Suborders of Cetaceans

• Mysticeti– Baleen Whales– 11 Species

• Odontoceti– Toothed Whales– 64 species

Mysticeti

• 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

Mysticeti Families• 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

Family Balaenidae

Family BalaenopteridaeBlue Whale

Fin Whale

Minke Whale

Humpback Whale

Family Eshrichtiidae

• Gray Whales

Odontoceti (toothed whales)

• 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

Sperm Whale

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

Beaked Whale

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

Belugas

Family Platanistidae

• 5 Species: River Dolphins

• Small dorsal fin

• Jaws form a long beak

• Flukes notched

• Many well developed conical teeth in both jaws

River Dolphins

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

Dolphins

Family Phocoenidae

» Porpoises» 6 Species: Dorsal fin large and triangular» Head blunt, no beak» Well developed to poorly developed spatulate teeth

in both jaws

Porpoises

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

• 1 Species Dugong dugon

• Nails absent

• Tail modified into notched flukes

• Male and female approximately the same size

Dugong

Family Trichechidae

• 3 Species of Manatee

• Vestigial nails present

• Tail modified into rounded paddle

• Male and female approximately the same size

Manatees