Presentation on theme: "Marine Mammals Lesson 9.5 Great white shark, hump-backed whale breaching, sockeye salmon spawning, male and female elephant seals."— Presentation transcript:
1 Marine Mammals Lesson 9.5Great white shark, hump-backed whale breaching, sockeye salmon spawning, male and female elephant seals.
2 Diverse groups of landmammals that have adaptedto life in the ocean: all havehair, bear live young andnurse their offspringThey include:-sea otters and polar bears-seals, sea lions and walruses-manatees and dugongs-whales, dolphins and porpoises
3 Sea Otters Sea otter is the smallest marine mammal and has no blubber layerinsulation from air trappedin its thick fur.Otters use tools like rocksto crush shells of abaloneand other shellfishOtters help to keep kelpforests healthy by eatingsea urchins, which graze onkelpThis helps preservebiodiversity of ocean food webHunted for its fur and killedby fishermen, its numbershave declined
4 Polar Bears Polar bears are semi-aquatic spend much of their lives on drifting Arctic ice.They feed primarily on seals, butalso whale and walrus carcasses.Male polar bears may grow to10 feet tall and weigh over 1400 lb.Females may reach seven feet andweigh 650 lb.Polar bears have been known toswim 100 miles at a stretch.They are found in the Arctic, Alaska,Canada, Russia, Greenland, andNorway.Humans are their main predatorsGlobal warming threatens polarbear populations by melting the seaice, which is their main habitat.
5 Seals, Sea Lions and Walruses Have paddle-shaped flippers forswimming, but must rest andbreed on land”Blubber” = thick layer of fat forinsulation, food reserve andbuoyancyMany are large, which helps toconserve body heat in coldwatersElephant seals are the largest:males can be 20 ft long andup to 5,000 lb.Elephant seals can dive for 1.5hours without coming up for airWalrus tusks are used for defenseand to anchor the animal to the ice.M. Parker
6 Elephant seal research at Sonoma State University Dr. Dan Crocker with a bull elephant seal (anesthetized!) at Ańo Nuevo State Park in San Mateo County, fitting it with tracking devices to study its diving physiology and migration patterns. The scars on the seal’s back and snout are from fighting with other males during the breeding season, which is the only time that males are found on land. Females stay longer to give birth and wean their pups.
7 Manatees and Dugongs Sirenians, also known as “sea cows,” are named for mermaidsThese gentle mammals are related toelephants!only marine mammals that are strictvegetarians, feeding on sea grasses andother vegetationManatees larger, up to 15 ft long andover 1,300 lb.Hunted by humans for oil-rich blubberand meatSlow reproduction– 1 calf every 3 yr.Manatees found in Atlantic Ocean, theAmazon, Florida, S. AfricaDugongs only marine, from E. Africato western Pacific islands.Manatees have been injured and killedby collisions with boat propellers inFlorida; now have speed restrictions insome manatee habitats
8 Dolphins, Porpoises and Whales Along with sirenians, mostcomplete transition to marine life;spend their entire lives in the water.convergent evolution: theseanimals look very fish-like, butbreathe air, are warm-blooded andnurse their young.Front flippers only, some havedorsal fins like fishBlubber for insulation, buoyancyHair almost absentNostrils on top of head = blow-holeMany highly intelligent– malehumpback “songs” thought tocommunicate mating fitnessCan be heard for 100 miles!
10 Baleen whales Largest whales on earth are krillLargest whales on earth arebaleen, which eat tiny shrimp-likeanimals called krillNo teeth, but rows of flexiblefibrous plates made of keratin thathang from the upper jaws.It filter-feeds by gulping a hugemouthful of water and squeezing itout through the baleen to strain outfood particlesLargest baleen whales are theblue whales -- can reach lengths offt; weight up to 140 tons!(That is 280,000 lb!)If the average teenager weighed140 lb, 2000 teens = one blue whale!
11 80 species of toothed whales, including dolphins and porpoises Numbers of teeth vary from 2 (narwhal) to over 100 in some species of dolphinsMost smaller than baleen whales, although killer whales can reach 26Largest is sperm whale (“Moby Dick”) at 60+ ft.Toothed whales eat fish, squid, shrimp, penguins, pinnipeds.
12 March 2012 whale hunting in the Southern Ocean near Australia Humans have hunted whales for centuriesSubsistence vs. commercial hunting (Inuits vs. Japan, Norway, Iceland)Very controversial animal rights issue (Green Peace, Sea Shepherd)
13 A happy note: the annual gray whale spring migration of females and calves, from Baja California to Alaska is happening now. You can watch this migration on the Sonoma and Marin coasts!gray whale and calf