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Marine Mammals Review. Chapter 6. The basics. Marine Tetrapods. 4 limbs Breathe air with lungs Terrestrial ancestor species Reptiles, birds, mammals + 1 species of frog in Asia. Identifying Marine Mammals. Part 1 of test.
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Chapter 6 The basics
Marine Tetrapods • 4 limbs • Breathe air with lungs • Terrestrial ancestor species • Reptiles, birds, mammals + 1 species of frog in Asia
Identifying Marine Mammals Part 1 of test You will be identifying BY ENGLISH, COMMON NAME, not latin species name.
Part 2: How do mammals live in the ocean? FYI Fossil and DNA evidence shows that the ancestors of ocean mammals were LAND mammals.
Traits of ALL Marine Mammals • Viviparous (internal nourishment and development of fetus) • Body hair (on many but not all) • Mammary glands • Specialized teeth (type of teeth corresponds to type of food) • External opening of reproductive system DIFFERENT from external opening of digestive system
Pinnipeds • Fin footed mammals • Carnivores • Walrus, seal species, sea lion species • Only one species of walrus • Seals swim w/ rear flipper for power • Sea lions swim w/ front flippers for power
Manatees + Dugongs Paddle like tails No pelvic limbs Herbivores Shallow tropical oceans
Cetaceans (whales) • No pelvic limbs (do have remnants of pelvic bones in skeleton!) • No body hair • Dorsal blowholes for breathing • Swim w/ horizontal tails for power • Baleen- adaptation for filter feeding in some whales • Toothed whales- carnivores
Breathing • Hypoxia- state of small amounts of oxygen in the body • Must reach surface of water to breathe. • Amount of time spent underwater between breaths varies based on species • Rapid exhale-inhale pattern at surface then hold breath while underwater called APNEUSTIC BREATHING PATTERN • Lungs collapse from water pressure in deep dives- marine mammals can handle this!
Don’t memorize, but be impressed! @ ~100 meters under water the lungs collapse completely
HOW??? • Oxygen forced out of lungs as they collapse • store oxygen in red blood cells • Have more red blood cells than humans
Communication • Sound! They “sing” to each other. • Humpback Whale "songs“ • For reproduction and hunting • Behavior- watch each other’s movements and move in appropriate response. • Dolphins play and hunt in groups • Orca's use sound and visuals to hunt together
Reproduction • Sexual reproduction • Live birth • Babies must be able to swim with mom immediately • Milk often has very high fat content to help babies grow fast • Time the mother’s spend with baby varies greatly • mother and calf gray whale Baja Mexico • FYI Newborn gray whale ~16ft long, compared to mother ~49ft long!
Part 3: Mammals in the North and South Poles Chapter 12
This week • Friday Starting Thursday, ending Friday we are watching the Blue Planet episode about the North and south Pole ecosystems
NORTH: Arctic Mammals • Polar bears, harp seals, hooded seals, ringed seals, walruses, gray whales, killer whales, beluga whales, narwhals
Adaptation: Milk Fat • Milk produced can be up to 60% fat so the baby gains weight quickly. • Cow’s milk 3-5% fat • Needed because newborns do not have enough fat and fur to stay warm on their own. Adults need to maintain large amounts of blubber/fat in order to survive in the cold water/air. Hooded Seals: Baby weaned after 4 days!
Adaptation: Migrating animals • Cold water contains more small organisms to feed on than warm water • Gray Whales migrate 18,000km per year: • Summer near Bering Sea (lots of food) • ~September leave and start swimming south • January-March near Baja, Mexico (calves born there) • ~April leave and start swimming north again
Time on Land v. in water • Common for sea mammals to give birth OUT of water • WHY??? • What common traits do you see in the seal pups below? (cute doesn’t count!) • EXCEPTION: Cetaceans
Mating Areas on land • EXAMPLES: Walrus leks • Lek- arrangement where males pick a spot and show off, females get to decide which male with mate with • FYI walrus gestation= 15 months! Baby spends about 1 year living off milk from mom. • walrus on russian coast
Why are polar bears considered sea mammals? • Ursusmaritimus • Hunt on sea ice • Will swim long distances for the next meal
Polar bears • Polar bear video (on DVD) • https://maps.google.com/maps?q=churchill+canada&ie=UTF-8&hq=&hnear=0x526fd949c8f9f537:0xd10c44d8423762dd,Churchill,+MB,+Canada&gl=us&ei=bOomU-uMIIfF0QGCi4GgCA&ved=0CKkBELYD • YES, polar bears have black skin. WHY is that useful? • Polar bear fur is not actually “white”, but nearly see-though. (like a dusty window)
How Baleen Whales Eat • Skimming • Engulfment • Gray whales have short baleen therefore a different way of feeding
Toothed Whales in Arctic All carnivores Living in groups called “pods”
And the strange animal award goes to… • THE NARWHAL • Eat fish and squid in deep arctic waters • 1 tusk on males(left incisor tooth) • Can sense salinity, temperature, and pressure of water!
Adaptations for Hunting • Echolocation (like sonar that submarines use) • Works for schools of fish, not good for mammals or individual fish • Vision and Brute force • Works for individuals or small groups of hunters going after other sea mammals • Orca hunting video shown last week
SOUTH: Antarctic Mammals • Weddell, crabeater, leopard, elephant seals • Humpback, orca, minke, fin whales
For the most part animals in the antarctic require similar adaptations as those in the arctic • Need to survive cold air/water • Need to eat enough • Need to avoid predators
Adaptation: teeth • Teeth are designed for the animals specific prey species • Small or large teeth or baleen I hope the penguin moved after this picture was taken!
Surprising uses of teeth • Weddell seal uses teeth to scrape open an air hole in ice. • Teeth become smaller and duller over time • Animal becomes less proficient at finding prey • Weddell seals tend to have shorter lives than other species.
How humans changed Antarctic Ecosystems • Cold water = many fish • Overfishing and whaling in last 100 years • Fewer larger mammals and more smaller mammals • Example: ~30000 blue whales feeding in 1929, ~2000 blue whales feeding 2010 • Remember the moral of Happy Feet!
The Antarctic Food chain • Depends on krill • Top predator is IN the water: Leopard Seal • leopard seal hunting
Toothed whales • All are migrating animals • Here Killer Whales mainly eat seals • Sperm whales are most widely distributed whales on earth Think Moby Dick.
Final Thought Question • Why are the arctic and antarctic ecosystems vital to the entire world even though they have fewer types of organisms than other areas?