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 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 Flatback Sea Turtle Black Sea Turtle

Leatherback Sea Turtle Kemps Sea Turtle Leatherback 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

Wading, do not have webbed feet Live inland as well as sea 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

Whaling Early as 6000 B.C. Blubber used to make soap and lamp oil Baleen used for corsets Meat

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

Marine Mammal Protection Act of 1972, 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