chapter 9: marine reptiles, birds, and mammals. vertebrates 350 m.y.a. vertebrates invaded land...
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Chapter 9: Marine Reptiles, Birds, and Mammals
Vertebrates
350 m.y.a. vertebrates invaded land
Decendents of bony fish
Land vertebrates had to adapt to harsher conditions on shore
Tetrapods had to develop lungs that allowed for absorption of oxygen directly from air.
Tetrapods had to evolve in ways to keep from drying out.
Amphibians, early tetrapods, have eggs that are vulnerable. They need to stay moist and lay them in water.
Reptiles on the other hand solved the problem of waterloss, resulting in the evolution of birds and mammals.
One they were equipped with adaptations for land they reentered the ocean.
Classification
Marine Reptiles
• 7000 species
• Dry skin with scales
• Eggs leathery shell
• Poilkilotherms (body temp varies w/environment) and ectotherms (lose metabolic heat to environment)
Sea Turtles
• Shell, carapace, is fused with their backbone.
• Cannot retract their heads into the shell
• Legs are modified into flippers for swimming
• Warmer waters
Feed on seagrass, seaweed, sponges, sea squirts, barnacles, jellyfish
Must return to land to reproduce
Migrate to original beach, possible use of magnetic fields
Return every 2-4 years, copulate offshore, females come on shore at night, dig a hole lay between 100 – 160 eggs, hatch approx. 60 days
7 (8) species of Sea Turtles (all classified as threatened);
Green (Chelonia mydas)
Hawksbill (Eretmochelys imbricata)
Leatherback (Dermochelys coriacea) D.o.d,largest turtle
Kemp’s Ridley (Lepidochelys kempii)
Loggerhead (Caretta caretta)
Flatback (Natator depressa)
Black (Chelonia agassizii)
Olive Ridley (Lepidochetys olivacea)
Green Sea Turtle
Hawksbill Sea Turtle
Black Sea TurtleFlatback Sea Turtle
Kemps Sea TurtleLeatherback Sea Turtle
Loggerhead Sea Turtle Olive Ridley
Sea Snakes
Approx. 55 species found in tropical waters
Laterally flattened and tail paddle-shaped for swimming, 3-4ft long
Mate in the ocean, ovoviviparous
Closely related to cobras, rarely aggressive
Marine Iguana (Amblyrhynchus cristatus)
Galapagos Islands
Eats seaweed and can dive 33ft to graze
Saltwater Crocodiles (Crocodylus porosus)
Mangroove swamps and estuaries
20-33ft long, very aggressive
Seabirds
Endothermic
Waterproof feathers
Hollow bones
Hard-shelled egg
Spend significant amount of time in marine environment and eat marine organisms
Penguins
Flightless, wings modified into stubby flippers
Bones are denser to reduce buoyancy
Layer of fat and dense waterproof feathers
Feed on fish, squid, and krill
Lay eggs during cold times of year to ensure food availability when egg hatches
Emperor penguin (Aptenodytes forsteri) mate for life
Fig. 9.7
Fig. 9.8
Frigate Bird
Shorebirds
Wading, do not have webbed feet
Live inland as well as sea
Plovers, sandpipers, rails, coots, herons, egrets, and even ducks
Marine Mammals• 200 m.y.a• Class Mammalia• Endotherms• Hair, mostly viviparous (embryo receives nutrients
and oxygen through the placenta), mammary gland
Pinnipeds – Order Pinnipedia• Paddle-shaped flippers for swimming• Predators, fish and squid• Streamlined bodies• Coldwater, thick layer of fat (blubber)• Breed on land
Seals• Largest group,
rear flippers that cannot be moved forward
• They move on land with front flippers
• Harbor Seals• Elephant Seals
Sea Lions and
Fur Seals• Eared seals• Move rear flippers
forward• Use all limbs to
walk/run on land• Graceful swimmers• Males much larger than
females• California sea lion
Walrus (Odobenus rosmarus)• Tusks are used for defense• Feeds on invertebrates that it sucks up from the sea
bottom• Dependent on sea ice
Odobenus rosmarus
Sea Otter and Polar Bear• Order Carnivora• Sea Otter (Enhydra lutris)• Smallest marine mammal averages between 60 – 80
pounds• Lacks layer of blubber instead uses air trapped in its
dense fur• Breed and give birth in water, eats up to 30% of its
body weight/day (invertebrates and fish)• Lives in kelp beds
Polar Bear (Ursus maritimus)• Semi aquatic animals that live in the Arctic and feeds
primarily on seals• Depends on sea ice for survival
Manatees and Dugong (sea cows)• Order Sirenia, relatives of elephants• Pair of front flippers, no rear limbs• Paddle – shaped horizontal tail• Blubber, live in shallow coastal waters• Strict vegetarians, large in size Dugongs (10ft) and
Manatees (15ft)• Manatee (Trichechus)
Whales, Dolphins, and Porpoises• Order Cetacea• Bodies are streamlined, breath air, warm-blooded, have hair,
and produce milk for their young• Front flippers, no rear limbs (embryonic stage only)• Many have dorsal fin, muscular tail fin-like (fluke)
• Blubber, provides insulation and buoyancy• Single or double opening on the top of their head –
blowhole• 90 species, all marine except 5 freshwater dolphin
species• Divided into two groups; toothless and toothed
Fig. 9.15
Baleen (toothless) whales, Mysticeti• Rows baleen hang from upper jaws made up of
keratin• Largest whales, 13 species• Blowhole has two openings• Blue Whale (Balaenoptera musculus)
– Largest, males up to 80ft and females up to 110ft– Weigh up to 90 – 140 tons
• Feed by gulping up schools of fish and swarms of krill
Toothed Whales, Odonticeti• 80 species • Teeth
– Food is swallowed whole not chewed• Blowhole has one opening• Largest toothed whale is the sperm whale
Fig. 9.18(Contd.)
• Dolphins tend to be classified by their distinctive beaks
• Porpoises have more blunt shorter “noses”. • Bottlenose
WhalingEarly as 6000 B.C.Blubber used to make soap and lamp oilBaleen used for corsetsMeat
• 1800s • harpoons and steamships
made whaling easier• Population decline • whales have long life
spans mammals• slow reproductive rate• slow swimmers
• Factory ships• Reached it peak in 1930s• Right whales
• 1946, International Whaling Commission (IWC) in attempt to regulate whale hunting– IWC collected data and set annual quotas
• Marine Mammal Protection Act of 1972, – US Congress banned the hunting of all marine mammals
in the US waters and importation of marine mammal products (except in traditional fisheries of AK natives)
Tab. 9.2
Biology of Marine Mammals
Swimming
• Streamline• Use their flippers, tails and flukes up and down• Blowhole on the top of their head• Blubber
Fig. 9.25
Diving• Adaptations
– efficient exchange of air on the surface– storage of more oxygen in the blood and muscles as
result of high concentration of hemoglobin – reduction of the blood supply to the extremities– collapsible lungs to help prevent the bends.– slow their heart rate down conserving oxygen– tolerance to lactic acid in their muscles
Fig. 9.26
Echolocation• Nature’s Sonar• Emitting sound waves and listen for the echoes to
reflect back from surrounding objects• Short bursts of sharp clicks
Behavior
Migration
Reproduction
• Delayed implantation (Pinnipeds)• Little is known about cetacean reproduction. • Gestation lasts for 11 to 12 months in most cetaceans. • Calves are born tail first• They can live more than 40yrs.
Tab. 9.3