学英语 - 海洋中的哺乳动物与鸟类 marine mammals & birds

Countercurrent Exchange
Concurrent exchange
Countercurrent exchange
Marine Birds
Salt Excretion in Birds
Penguins: • 17 species found in southern hemisphere • Spends 75% of lifetime in water
Fusiform Shape and Streamlining Evolutionary Convergence
Two basic bioenergetic strategies used by animals :
• Endothermy “warm blooded”
• Ectothermy “cold blooded”
• • • 34 known species Evolved 20 mya from Order Carnivora (ancestors of dogs and bears) Differ in possession of external ears and mode of locomotion
Differences between seals and sea lions/fur seals
tmammoth
tmastadon tStellar’s
sea cow
Dugong
Ancestral mammals
West Indian manatee Brazilian manatee West African manatee Other mammals
80
60
40
20
0
Million owk.baidu.com years before present
Nesting
Nests on pack ice
Marine Mammals
Marine mammals
• Characteristics of marine mammals:
– Warm-blooded – Breathe air – Have hair (or fur) – Bear live young – Females have mammary glands that produce milk for their young
– United States, Canada, Russia, Greenland and on the Arctic islands of Norway – Male: 10 feet tall and weigh over 1400 lbs – Female: seven feet and weigh 650 lbs – wild polar bears live up to age 25.
• Hunt seals and walruses, occasionally cetaceans
Range: • Circumpolar in Arctic • Range depends on sea ice
• normal range occasional range over pack occasional range over permanent ice
10,000
Dugong Range
Family Dugongidae
Dugong dugong
8.9 ft, 551-661lbs
Steller's Sea Cow tHydrodamalis gigas Discovered 1741, extinct 1768. 30ft, 4.4 tons
– Manatees – Dugongs
Manatee & Dugong
• Most complete transition to marine life along with whales and dolphins • Related to the elephant, but common ancestor didn’t look like either of them • Once many more species around • Large layer of blubber • Origin of the mermaid myth • Herbivores • Nostrils on top of snout have valves to keep water out • Both species have one calf at a time • Tend to have a single calf every 3 years
Marine Mammals & Birds
Return to the Oceans Mammals have returned to the oceans multiple times Adaptations • vivipary • suckling young • thermoregulation • feeding • diving • osmoregulation We’ll look at adaptation in marine mammals from the least to the most
Dugong
Location: coastal and inland waters of the western Indo-Pacific region • Dugongs are exclusively marine and have a dolphin-like tail • Dugongs tend to dig seagrass rhizomes • Predator includes tiger sharks
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• •
Threats: • Careless boaters • Habitat loss
Manatee
9.8 ft, 800-1200lbs 3,000 in U.S.
Relationship between Sirenians and elephants (mtDNA)
Asian elephant African elephant
Pinnipeds
Pinnipeds
Hawaiian Monk Seal Family Phocidae
Walrus Sea Lion Family Otariidae Family Odobenidae
Biology and Natural History
Order Pinniped (seals, sea lions, & walruses) Family Phocidae- true, earless seals Family Otariidae- eared seals and sea lions Family Odobenidae- walruses
Hawaiian Monk Seal Family Phocidae
• • • •
Lack external ears Hind flippers propel them while swimming Front flippers act as rudders Travel on land is difficult (wiggle)
Penguin Adaptations: • • • • • • Heavy, solid bones for diving Watertight feathers (up to 70 per sq. in.) Blubber for insulation Oil gland for coating feathers Black & white counter shading Deep divers - 500 m, 15 min. • Paddle-like feet • Streamline, fusiform body - 15 mph • Social
Marine mammals: Order Sirenia
• Sirenian characteristics:
– Large body size – Sparse hair all over body – Vegetarians – Toenails (on manatees only)
• Includes:
• Walrus • Seals • Sea lions/fur seals Hawaiian Monk Seal
Sea Otter
Sea Otter
• Enhydra lutris
– Native to north Pacific – 394,000 hairs/cm2 – No blubber – Female 45 lbs; Male 65lbs – Diet: Sea urchins, abalone, mussels, clams, crabs, snails and about 40 other marine species.
– Good swimmers – Thick blubber
– Thick fur
Polar bears
• Polar bears are the least adapted to the marine lifestyle • Land animals that are adapted to the cold • Considered marine mammals because they feed almost exclusively on marine organisms • Very good swimmers, but can’t dive below surface well
Manatee
Location: Florida, Central and South America • Manatees have paddle-like tails and frequent freshwater Manatees tend to crop and grab with prehensile lips Manatees are larger than dugongs Few predators
Adaptations for diving • Exchange a large amount of air on each breath • Up to 90% in each breath (humans exchange about 20%) • Blood with more oxygen carrying capacity • Heart rate slows • Blood flow shunted • Higher concentration of myoglobin in the muscles • Collapsing lungs • Dive with no air in contact with blood vessels to avoid problems of nitrogen being forced in
Marine mammals: Order Carnivora
• All members of order Carnivora have prominent canine teeth • Includes:
– Sea otters – Polar bears – Pinnipeds (flipper-footed)
Sea Lion Family Otariidae
• • • •
Eared seals Front flippers propel animal when swimming Rear flippers act as rudders Fairly mobile on land
– Uses tools
– Dives to 330 ft
– Rests in coastal kelp forests
Polar Bear
Pop size: 22,000 to 27,000 Weight: 550 to 1,700 pounds
Polar Bear
• Ursa maritimus