1. Marine reptiles, Birds, and Mammals

2. Marine Reptiles: Body Systems
Have a sophisticated brain, central nervous system, and lungs.
Some snakes only have one lung.
Have a three chambered heart with the exception of crocodiles, which have four chambers like mammals or birds.
The digestive system of reptiles differs from other vertebrates in that waste, including that from the urinary system, the sexual organs, and the digestive system, empties into a holding tank called the cloaca. In the cloaca, water can be reabsorbed into the body to be used again.

3. Marine Reptiles: Reproduction
They reproduce through internal fertilization.
Male lizards and snakes often have two penises; most male turtles and crocodiles have one.
The two penises are referred to as hemepenes and the animals only use one of them while mating.
Species that mate with more than one female at a time usually alternate the hemepenes.
Most reptiles lay eggs, although some lizards and snakes actually give birth to live young.
Reptile eggs contain yolk and protein and are protected by a leathery or hard shell, which allows carbon dioxide and water to be exchanged while protecting the embryo from drying out or consumed by bacteria.

4. Marine Reptiles: Class Testudines
The more than 250 species of turtles and tortoises all have a protective shell surrounding their body.
They range in size from the huge leatherback sea turtle, which can reach up to 8 ft long and weigh over 2,000 lbs to the smallest bog turtle that measures only 4.3 in at most.
Turtles that live in water have a lighter, flatter shell than the terrestrial species.

5. Marine Reptiles: Class Squamata
The Galapagos Islands are home to marine iguanas, the only lizards that venture into the ocean.
Unlike other reptiles, snakes lack outside ears and have eyes covered with permanent transparent scales.
Snakes have adapted to almost all habitats in the world and can also be found on lakeshores and even in ocean waters.
Sea snakes have a specially adapted flat tail that makes it easier for them to swim.

6. Marine Reptiles: Class Crocodilia
Include alligators, crocodiles, gavials, and caimans.
Measure anywhere between 6 to 13 feet long
some, like the saltwater crocodile, can reach up to 33 feet.
Usually found in tropical waters, although some alligators live in temperate climates especially in the US and China.
Crocodilians have long flattened tails that enable them to swim efficiently through water.
They breathe through nostrils located at the top of their head.

7. Marine Birds: Adaptations
The preening gland releases waxes and water repellant fats that create a protective shield on the bird to prevent water from saturating the feathers.
This protective shield also keeps the bird insulated and, when combined with feathers made out of dusty keratin, the bird is waterproof.
Salt glands allow marine birds to drink salt water and expel the unusable salt from their bodies.
Salt glands work by condensing salt from the blood into the sinuses allowing the bird to sneeze out the excess.
Other marine birds push out salt directly from the glands. The freshwater needed for survival comes from their prey.

8. Marine Birds: Bill Adaptations
The curved bill found in penguins and cormorants is an adaptation that helps birds bring fish into their throat.
Some have a distensible pouch such as those found in pelicans, frigate birds, and cormorants.
This pouch is located between the two parts of the lower mandible and is used to drain water from around the fish before it is eaten.
Cormorants and Anhingas use the hooked bills to puncture their fish.
Frigate birds snatch fish from other birds.
Flamingos have a beak that can filter small invertebrates, algae, and other small organisms from water.
These birds have long bills and long legs, enabling them to stand in shallow water while searching for food.

9. Marine Birds: Hunting Strategies
Many birds will fly directly above the surface and look for fish swimming below.
Black skimmers fly close to the surface and pluck fish at the top out of the water.
Gulls and terns like to fly higher to view the fish and plummet from the air to snatch the fish out of the water.
The penguin is an unusual but very familiar marine bird that can dive down into the ocean to look for fish.

10. Marine Birds: Other Adaptations
Marine birds also have many different types of legs and feet.
If a bird has very short legs with webbed feet, it is probably a very powerful swimmer.
Webbed feet are referred to as totipalmate feet and partially webbed feet are referred to as palmate feet.
Birds that do a lot of swimming often rely upon what is called countercurrent exchange to keep the cold blood flowing up and away from their feet from shocking their body.
The arteries in these birds run very close to veins on the way up and are warmed enough that the bird can swim in very cold water without negative effects.
Many marine birds also have very well developed eyesight and an amazing sense of smell.
Birds like the tube nosed bird, petrels, and the albatross can smell food 30 km away.

11. Marine Mammals: Adaptations
Marine mammals are vertebrates that have hair or fur, are warm blooded, use lungs to breathe air, bear live young, and produce milk through mammary glands.
Marine mammals are very similar to land mammals with the exception of the thick layer of blubber instead of thick fur for insulation.
They typically have long, stream-lined bodies, which allow them to move swiftly through the water.
Although they breathe air for oxygen, they are also able to stay under water for long periods of time because of their ability to hold extra oxygen in muscles and in the blood.
Many marine mammals have an excess amount of blood and can direct it to the most important organs when necessary.
They can also slow their heartbeat for more efficient oxygen use when diving.

12. Marine Mammals: Cetaceans
Whales are divided into the Baleen whales and the Toothed whales.
Both types of whales have highly developed senses, blubber to keep warm and long bodies enabling them to swim quickly.
Baleen whales have baleen plates instead of teeth composed of rigid fibers that act like a filter to catch zooplankton and phytoplankton. The upper jaws of Baleen whales are long and flat.
Toothed whales and dolphins are able to use teeth to catch prey.
Animals like fish, octopus, squid and even other whales are swallowed whole and head first after being turned around by a powerful tongue.
Dolphins are different from the whales due to cone-shaped teeth, a curved dorsal fin and a lengthy rostrum.
Dolphins have a larger brain than porpoises
Porpoises have a more rounded nose, a triangular shaped dorsal fin and spade-like teeth.

13. Marine Mammals: Pinnipeds
There are three families of seals which include the True seal, the Eared seal and the Walrus.
Although seals have blubber, they are warm blooded.
They can live on land or in water.
Seals can live out at sea for months at a time only returning to land for the mating season and to moult. Seals are found all over the world in coastal areas with many nutrients.
The fur seals and sea lions are part of the Eared seal family.
These animals have large flippers in the front, tiny ear lobes and webbed back legs that can rotate around.
For this reason, Eared seals are capable of moving quite easily when in water or on land.
True seals are easily distinguishable from the Eared seals mostly because they look very awkward when trying to move on land.
No ears, short flippers and no rotation of the back flippers,
Walruses have a little hair on their body but not much, long tusks and short little whiskers.
They are also quite a bit larger than other pinnipeds.

14. Marine Mammals: Sirenians
There are three species of Manatees and one species of Dugong.
Dugongs and manatees are gentle animals with oversized front flippers.
Although Dugongs have many of the characteristics of other marine mammals, they have a higher blubber ratio. Dugongs have a dolphin-like tail and are found in throughout Australia.
Manatees are characterized by a round tail and can be found in North American waters, West India, and West Africa.

15. Marine Mammals: Carnivoras
Include polar bears and sea lions
Polar bears are the largest of all carnivores that live on land and are found throughout the arctic on sea ice, islands, coastlines and in the water.
These amazing predators often feed on ringed or bearded seals.
The skin of polar bears is black and the fur is actually clear.
They appear off-white because of their highly reflective coat and dark skin.
Polar bears are protected from extreme temperatures with a thick layer of blubber and have adapted long necks and bodies for more efficient swimming.