Marine Reptiles, Birds, and Mammals

Vertebrates

• Vertebrates originated in the ocean 350 million years ago

• Vertebrates descended from bony fish

• Land dwelling vertebrates are called tetrapods, meaning four-footed

Marine Reptiles

• Around 7,000 species of reptiles

• Skin is covered by scales to help prevent water loss.

• Reptiles are ecthotherms, or cold-blooded

• Their activity level varies by temperature, they are much less active in the cold and are usually not found in cooler climates

Sea Turtles

• Bodies are enclosed by an armor-like shell, or carapace that is fused to the backbone.

• Sea turtles cannot retract their heads into their shells.

• Legs are modified into flippers for swimming.

• Largest sea turtle is the leatherback

• Most sea turtles feed on soft bottom dwelling invertebrates like sponges, soft corals, jellyfishes, and other harder invertebrates like crabs and molluscs.

• Sea turtles jaws are adapted for crushing

• All sea turtles must return to land to reproduce

• They lay their eggs on remote sandy beaches

•Sea turtles return to their nesting areas every 2 to 4 years. It has been recorded that a lot of females return to the beach where they were born to lay eggs. •Only females usually go on land. They excavate a hole in the sand to lay between 100 and 160 eggs. Eggs hatch after 60 days of incubation.

Sea Snakes

• They are laterally flattened with a paddle like tail for swimming. They are about 3 to 4 ft. long.

• Most live life completely in marine water. They are ovoviviparous, or give birth to live young, but a few species still come ashore to lay eggs.

• Sea snakes are carnivores, eating bottom fish, a few also eating fish eggs.

• Closely related to the Cobra, and are among the most common of all venomous snakes. Some with bites fatal to humans.

• Are not aggressive, and their mouth is not big enough to give a good bite. Don’t tread on me!!

Sea Birds• Sea birds are homeotherms or warm blooded. This

allows them to live in a wide variety of areas. • Bodies are covered with waterproof feathers that

conserves body heat.• Waterproofing is provided by oil that comes from a gland

above the tail. • Flight is made easier with their hollow bones.

• Seabirds that spend most of their lives at sea eat marine organisms. They eat fish, squid, and bottom invertebrates.

• They breed in large colonies, and pair with a mate for life. • True seabirds have webbed feet for swimming.

Penguins • Flightless birds with wings modified into flippers that

allow them to swim underwater. Their bones are denser than those of other birds to reduce buoyancy and allow easier diving.

• Penguins swim very well, but are clumsy and awkward on land. They are near-sighted due to eyes adapted to see underwater.

• Penguins have a layer of fat under the skin to help protect them from the cold.

• Dense, waterproof feathers trap air and warm the body by holding the heat.

• Larger penguins like the Emperor hunt for squid and fish. Small penguins mostly feed on krill.

• Emperor penguins mate for life. The male carries and incubates an egg for 64 days.

Tubenoses

• Tubenoses make up a large number of seabirds with distinctive tube-like nostrils and heavy beaks that are usually curved at the tip.

• Tubenoses include albatrosses, shearwaters, and petrels

• Tubenoses catch fish at the surface of the water, and some eat dead birds and whales, while others feed on krill and plankton

• They nest on remote islands, and cliffs that keep them safe from predators.

Pelicans and Other Birds

• These birds are very different looking but are grouped together because they have webbing between all 4 toes.

• They eat relatively large fish • Some of these birds like Pelicans dive in

the water and catch fish in their pouch• Birds like Pelicans, Cormorants, and

Frigate birds nest in large colonies along the coast. They build messy nests of twigs

frigate

cormorant

pelican

Gulls

• Gulls make up the largest variety of seabirds.

• Gulls are predators and scavengers who will eat almost anything

• Their slender beaks are specialized for catching small fish which they swallow whole.

Shorebirds

• These birds are waders. Most do not have webbed feet.

• Shorebirds are plovers, sandpipers, rails, coots, herons, egrets and even some ducks.

Marine Mammals

• About 4,600 species of mammals• Mammals are endotherms, warm-blooded• They have hair to retain heat• Most mammals are viviparous• Babies are fed by the milk secreted by the

mother’s mammary glands. • Mammals produce a few eggs, but have

well cared for young as opposed to producing millions of eggs

• The brain of mammals is larger in relation to their body size and is much more complex then that of other vertebrates.

Seals, Sea lions, and Walruses

• Seals and related marine mammals have paddle shaped flippers for swimming, but need to rest and breed on land

• This class, or pinnipeds are predators feeding mostly on fish and squid.

• Most pinnipeds live in cold water. They have blubber to keep them warm in these cold temperatures. Blubber also provides buoyancy.

• Seals move on land by pulling themselves forward with front flippers

• Male seals reach 20 ft. in length and can weigh as much as 4 tons.

• Monk seals are a kind that live in warm waters around Hawaii

• Walrus’ are large pinnipeds that have a pair of tusks protruding from the mouth

• Walrus eat bottom invertebrates, and mostly clams. They suck up their food as the move along the bottom

• Walrus tusks are used for defense and to anchor themselves to ice

Sea Otters and Polar Bears• Sea Otters are the

smallest of marine mammals.

• Otters lack a layer of blubber, it keeps warm from the air trapped in its dense fur

• They are playful and intelligent animals, who spend most if not all their time in water.

• They give birth and breed in water

• Sea Otters need to eat up to 25-30% of their body weight in a day

• They eat sea-urchins, abalone, mussels, crabs, fishes and other invertebrates

• They live in or around kelp beds in locations from Siberia to California

• Polar bears are semi-aquatic mammals. They spend a lot of their time on drifting ice.

• They eat seals which they stalk and attack when they surface to breathe or to rest.

Manatee and Dugong

• Manatee and Dugong are relatives of elephants

• They have a pair of front flippers, but no rear limbs. They swim with up and down strokes of their tails

• Manatee and Dugong live in groups, and are strict vegetarians.

• They use their large lips for feeding on sea-grasses and kelp.

• Manatees and Dugongs usually reproduce with one calf every 3 years.

• Only 4 species of these animals exist.

Whales, Dolphins, and Porpoises

• Whales, dolphins and porpoises are cetaceans.

• They breathe air and will drown if trapped underwater, and are warm-blooded.

• They produce milk for their young, and have small hairs on their body.

• Cetaceans have a pair of front flippers, dorsal fins, and the tail ends in a pair of fin like, horizontal flukes.

• Blubber provides buoyancy to cetaceans, and also warmth

• The nostrils of these animals differ from others because they are on the top of the head forming a blow-hole.

• Cetaceans are divided into two groups: filter feeding animals and carnivorous.

Baleen (toothless) Whales

Baleen Whale

•Instead of teeth – baleen plates (same material as hair and nails) •Takes in huge amounts of water and collects the food on the baleen plates•Largest whales

Minke Whale

Examples of baleen whales•Blue whale•Fin Whale•Humpback Whale

Toothed Whales

• Whales use their teeth to grab and hold prey, not for chewing

• In all cetaceans food is ground up in one of the three compartments of the stomach

• Sperm whales are the largest of all toothed whales

• Sperm whales eat giant deep-sea squids, larger fish, lobsters and other marine animals.

• Dolphins have a distinct snout, or beak. They are very playful, social and easily trained.

• They travel in groups called pods

• Tuna and Dolphins often eat the same fish and usually occur in the same places so dolphins sometimes get caught in fishermen’s nets.

Biology of Marine Mammals

• Streamlined bodies help for easy swimming. Pinnipeds use their flippers for swimming mostly, while sirenians and cetaceans use

their tails

in an up a

down motion

for movement.

Diving

•When surfacing - To avoid inhaling water marine mammals take very quick breaths. A fin whale can empty and refill its lungs in less then 2 seconds.• Pinnipeds -30 minutes, at maximum depths of 490-820 feet.•Plankton-eating whales rarely recorded below 300 feet.•Toothed whales – 900ft – 7000ft up to 85 minutes

Beaked Whale

• Deep diving animals had to develop several adaptations: holding their breath for a long time, keep their body temperature constant, slowing down the heart rate (bradychardia), supplying only vital organs with oxygen, and tolerance to lactic acid.

• Marine mammals blood also contains more red blood cells which carry more hemoglobin. Their muscles are also very rich in myoglobin which can store a lot of oxygen.

• Deep diving animals had to develop several adaptations: holding their breath for a long time, keep their body temperature constant, slowing down the heart rate (bradychardia), supplying only vital organs with oxygen, and tolerance to lactic acid.

• Marine mammals blood also contains more red blood cells which carry more hemoglobin. Their muscles are also very rich in myoglobin which can store a lot of oxygen.

•Deep diving animals had to develop several adaptations: holding their breath for a long time, keep their body temperature constant, slowing down the heart rate (bradychardia), supplying only vital organs with oxygen, and tolerance to lactic acid.

•Marine mammals blood also contains more red blood cells which carry more hemoglobin. Their muscles are also very rich in myoglobin which can store a lot of oxygen.

Echolocation

• Echolocation is an adaptation that is based on hearing• Most toothed whales, pinnipeds, and dolphins all echo-

locate• Mammals echolocate by emitting sound waves and

listening for the reflection back from surrounding objects. The brain then analyzed the reflection, and however long it takes for the sound to come back is how far away the object is

• Sounds used in echolocation consist of short bursts of short clicks that are repeated at different frequencies.

• The lower the frequency the farther the sound travels

• When locating nearby prey high frequency clicks are used, which cannot be heard by humans

• The clicks, squeals, and whistles come from air being forced through air passages while the blowhole is closed.

• Incoming sounds are received primarily in the lower jaw. The jawbones transmit sound to the inner ears

Behavior• The brain of mammals has

evolved and its complex

behaviors are based off

past experiences, not

instinct• The brain stores and

processes past

situations to respond

to changes in the

environment

• Most marine mammals are highly social and live in pods

• Vocalizations are used to communicate things throughout the group like: territory during breeding, recognize each other, attract mates, and express moods

• Many species also have actions to show moods. Dolphins that turn around with their mouths open is thought to be a threat, while slapping the water with their tail is a warning.

• Cetaceans are also noted for their playful behavior• A whale breaching can be considered to mean many things:

warning, scanning the surface of the water or land, ridding themselves of parasites, or just for fun

• A whale that is in trouble will be helped by many other whales around it. Members of a pod will not leave a wounded or dying member. Dolphins have been known to carry an injured member to the surface to breath. Mothers have also been recorded as carrying a still-born calf around until it rots

• When it comes to eating most toothed whales will work together during a hunt, or take turns eating and then hunting

• A behavior of whales that is a mystery is beaching. It is thought that some whales beach themselves because they are disoriented due to illness, storms or injury

Pinnipeds and cetaceans make seasonal migrations of thousands of miles from feeding grounds to breeding groundsMost toothed whales do not migrate at all, but they do move around for food

Migration

Reproduction

• Marine mammals have similar reproductive system to land mammals

• To keep the body streamline male cetaceans have an internal penis and testes

• The penis is extruded through the genital slit right before copulation, an opening anterior to the anus

• Pinnipeds breed on land or ice• During breeding season males establish mating territories, stop eating

and defend their territories by constant, violent fighting• They herd as many as 50 females into their territory, and keep all

other males away• Females give birth

to their pups on shore

and establish a strong

relationship with them

• Gestation lasts from about 11 to 12 months in cetaceans, but the exception is the sperm whale that has a gestation of 16 months