Marine Mammals

BIOL265

Orders of Marine Mammals The class mammalia has four orders

that are considered marine related according to some sources.. Cetacea (Dolphins and Whales) Sirenia (Manatees and Dugongs) Pinnepedia (Seals, Sea Lions, and

Walruses) Carnivora (Sea Otters and Polar Bears)

The dolphins, whales and porpoises belong to this order. They are free swimming, descending from the land-based •Suborder Mysticeti (baleen whales) including the humpback, bow whale, blue, sei…•Suborder Odonticeti ("toothed whales") include dolphins, orcas, and porpoises•The taxonomy comes from both Peter Evans' "Biology of Whales and Dolphins" and Leatherwood and Reeves' "Handbook of Whales and Dolphins"

“One school of thought maintained that the similarities in the teeth between ancient whales and an extinct line of carnivorous mammals known as Mesonychia suggested the two were related. The other school of thought held that whales shared common ancestry with Artiodactlya, the family of even-toed ungulates that includes pigs, camels, giraffes and hippopatami. The recent discoveries tend to support the latter hypothesis” (Science News, 9/24/01).

http://www.neoucom.edu/Depts/Anat/whaleorigins.htm

This site has an interesting development including a third theory of cetacea lineage being debated today

Skeleton of Mesonychian, the third theory of cetacean lineage

Rodhocetus, a whale that lived 47 million years ago

Blowhole

Melon

TeethEye

Dorsal Fin

Powerful Tail Fluke

Underwater Life

How do they do it? BBC video

Nasal passages lead to blowhole and nasal plug which prevents water from entering lungs. Some can stay under for 4 – 20 minutes. Sperm whales can stay under for 90 minutes!

They have MYOGLOBIN in the muscles which can bind large amounts of oxygen, thus releasing GLUCOSE to increase energy

Some cetacea can reduce oxygen to the digestive system while diving

Notice the Dolphin Skeletal Pattern

They can also use Lactate to produce energy which is not possible for other mammals

Cetaceans use ECHOLOCATION

Dolphins and Humans Dolphin Lifesavers pt. 2:

How Dolphins see with Sound

Order Sirenia-Sirenia is a small order of fully-marine mammals that

consists of 2 families, 2 genera, and 5 species, one of which is extinct.

-They are recognizable by their flattened tail and cow-like appearance; indeed, they are often called "sea cows."

-All animals in this order are ungulates (hoofed mammals) even though they have no legs. The flippers are the leg substitutes, and on the flipper tips can be found small hoofnails.

The 2 sub-orders are: ..Dugongidae (dugongs) 2 - (1 extinct) spp

..Trichechidae (manatees) 3 spp

Over 50 millions years, related to the elephant. Feeds on vegetation, at least 10% of its body weight per day

They belong to the family Trichechidea

Scientific names include geographic locations Trichechus manatusis the west indies manatee, but Florida has become a sub-species Trichechus manatuslatirostris

There are three species of manatee and only one dugong. The West African and Amazonian are the other 2 manatees besides the West Indies (with a Florida subspecies

Their relatives, the dugongs and the lost Arctic Sea Cows belong to the family Dugongidae

They can grow to 3000 lbs and average 1000 lbs. They are sexually mature between 5 and 10 years. They have a 12 – 13 month gestation period and usually have single calves at one time

They can live up to 70 years

Manatees are related to elephants, thus descendants of the “subundulates”

They cruise at 2 mph, but can reach speeds of 15 mph

Notice Rounded “Fluke”

Notice the Submerged Vegetation Beds

Notice the Forked Tail of the Dugong

Manatee swimming in canal in Florida

Dugong

Dugong Photo © Doug Perrine/Seapics.com.

Steller's Sea Cow

Include the… Earless Seals (Phocidae) Eared Seals (Otariidae) Walruses (Odobenidae) Spend time on land in

rookeries with young pups. Gestation time is about one year. They usually have one pup, sometimes two.

Pinnipeds have several adaptations for survival in the marine environment. Some of these include - Streamlined bodies (to ensure that excess energy is not expended). Sex organs and mammary glands, which are retracted into slits or pockets beneath the skin. Modified fins and flippers to reduce drag in the water.

No eyelashes (eye protection is achieved by copious production of eye mucus). Grey Seal Resting

Eared Seals include sea lions and fur seals that can use hind flippers to walk on land

Earless Seals (true seals) have less body hair and thick epidermis

Walruses in polar areas have thick fat layers and large tusks for digging mollusks, etc.

The scientific name for the otters is Enhydra Lutris which means otter in the water. Groups of otters are called rafts.

Sea Otters use stones help crush hard shells of their food.

SIZES Body length: 40-50 inches

Tail length: 10-15 inchesWeight: 55-80 lbs

Sexual Maturity: 3 years Mating season: Year-round Gestation: 8-9 months Number of young: 1 raised at 1 year

Polar bears are a potentially threatened species. They wander across the circumpolar north on the ice from Russia to Alaska, from Canada to Greenland and on over to Norway. Their estimated population is around 22,000 to 27,000.

The Polar Bear has white fur, while its nose, lips, and eyes are black. The white coloring camouflages the bear in its snowy and icy environment. The bear can grow to lengths of 8 feet long and stands 3-4 feet at the shoulder.

The Polar Bear is found near the North Pole, northern Canada, Alaska and Arctic Islands. It may also inhabit broken ice packs at northern edge of North American continent

The Polar Bear mates in April and May every other year. Litters of 1-4 (usually 2) young are born around November-January in a winter den. Cubs remain with their mother about a year and a half, denning with her the winter after their birth.

Save the Whales

Enough is Enough by Greenpeace