Can anyone please define sea mammals?

Question

in more than 3 sentences

Answer 1

A marine mammal is a mammal that is primarily ocean-dwelling or depends on the ocean for its food. Mammals originally evolved on land, but later marine mammals evolved to live back in the ocean.

There are five groups of marine mammals:


Order Sirenia: the manatee, dugong, and sea cow
Order Carnivora, family Ursidae: the polar bear
Order Carnivora, infrafamily Pinnipedia: the seal, sea lion, and walrus
Order Carnivora, family Mustelidae: the Sea Otter and Marine Otter
Order Cetacea: the whale, dolphin, and porpoise
Since different groups of marine mammals originate from different ancestors, this is a case of convergent evolution.

Since mammals originally evolved on land, their spines are optimized for running, allowing for up-and-down but only little sideways motion. Therefore, marine mammals typically swim by moving their spine up and down. By contrast, fish normally swim by moving their spine sideways. For this reason, fish mostly have vertical caudal (tail) fins, while marine mammals have horizontal caudal fins.

Some of the primary differences between marine mammals and other marine life are:


Marine mammals breathe air, while most other marine animals extract oxygen from water.
Marine mammals have hair. Cetaceans have little or no hair, usually a very few bristles retained around the head or mouth. All members of the Carnivora have a coat of fur or hair, but it is far thicker and more important for thermoregulation in Sea Otters and Polar Bears than in seals or sea lions. Thick layers of fur contribute to drag while swimming, and slow down a swimming mammal, giving it a disadvantage in speed.
Marine mammals have thick layers of blubber used to insulate their bodies and prevent heat loss. Sea Otters and Polar Bears are exceptions, relying more on fur and behavior to stave off hypothermia.
Marine mammals give live birth. Most marine mammals only give birth to one calf or pup at a time, and are never able to birth twins or larger litters.
Marine mammals feed off milk as young. Maternal care is extremely important to the survival of offspring that need to develop a thick insulating layer of blubber. The milk from the mammary glands of marine mammals often exceeds 40-50% fat content to support the development of blubber in the young.
Marine mammals maintain a high internal body temperature. Unlike most other marine life, marine mammals carefully maintain a core temperature much higher than their environment. Blubber, thick coats of fur, bubbles of air between skin and water, countercurrent exchange, and behaviors such as hauling out, are all adaptations that aid marine mammals in retention of body heat.
The polar bear spends a large portion of its time in a marine environment, albeit a frozen one. When it does swim in the open sea it is extremely proficient and has been shown to cover 74 km in a day. For these reasons, some scientists regard it as a marine mammal.

Answer 2

Sea mammals are, as the name implies, mammals that live exclusively or primalrily in the sea. Mammals being defines as creatures that give birth to live young, produce milk from mammary glands, breathe air and have fur. This includes creatures like whales and dolphins that are entirely bound to oceanic life. These creature do not come onto land at all except as an accident as in the case of beachings where the animal dies soon afterward. There are also creature like seals, sea lions and walruses that spend most of their time in the ocean, but come on to land to breed and give birth. There is also the sea otter that splits it tiem between land and sea. It is, I believe, the only sea mammal that sitll has actual legs.

Answer 3

any member of the group of vertebrate animals in which the young are nourished with milk from special mammary glands of the mother. In addition to these characteristic milk glands, mammals are distinguished by several other unique features. Hair is a typical mammalian feature, although in many whales it has disappeared except in the fetal stage. The mammalian lower jaw is hinged directly to the skull, instead of through a separate bone (the quadrate) as in all other vertebrates. A chain of three tiny bones transmits sound waves across the middle ear. A muscular diaphragm separates the heart and the lungs from the abdominal cavity. Only the left aortic arch persists. (In birds the right aortic arch persists; in reptiles, amphibians, and fishes both arches are retained.) Mature red blood cells (erythrocytes) in all mammals lack a nucleus; all other vertebrates have nucleated red blood cells.

Answer 4

Sea mammals are mammals that live in salt water. Mammals breathe oxygen from the air (blowhole), bear and nurse children (rather than laying eggs), are warm blooded and have hair, not scales. Examples are seals, dolphins, and whales.

Answer 5

Mammals are living things in the kindgom Animalia that have mammary glands. That is their unique identifying characteristic...nothing else. If they're sea mammals, they are living things in the kingdom Animalia that have mammary glands...that live in the sea.

hmm..that's only 3 sentences. And yet, that's it.

Answer 6

Mammals, (this is animals that have their descendants alive, not by eggs, and that give them to suck milk) and that live in the sea. Example: Whales, seals, sea lions, etc.

Answer 7

A marine mammal is a mammal that is primarily ocean-dwelling or depends on the ocean for its food.

Check this link for detailed info and pick what you want.
http://en.wikipedia.org/wiki/Sea_mammals

Answer 8

Hi. Creatures that give birth to their young, give milk to their babies, have fur, and are warm blooded, that also live in the sea or ocean.