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