Mermaid

A mermaid is a mythological aquatic creature that is half human, half aquatic creature (e.g. a fish or dolphin). Various cultures throughout the world have similar figures. The word is a compound of mere, the Old English word for "sea," and maid, which has retained its original sense. Mermaids appear to have the tail of a fish and the torso of a woman.

Much like sirens, mermaids would sometimes sing to sailors and enchant them, distracting them from their work and causing them to walk off the deck or run their ships aground. Other stories have them squeezing the life out of drowning men while attempting to rescue them. They are also said to take humans down to their underwater kingdoms. In Hans Christian Andersen's The Little Mermaid it is said that they forget that humans cannot breathe underwater, while others say they drown men out of spite.

The sirens of Greek mythology are sometimes portrayed in later folklore as mermaid-like; in fact, some languages use the same word for both bird and fish creatures, such as the Maltese word 'sirena'. Other related types of mythical or legendary creature are water fairies (e.g. various water nymphs) and selkies, animals that can transform themselves from seals to humans.

Penguin

are a group of aquatic, flightless birds living almost exclusively in the Southern Hemisphere. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have become flippers. Most penguins feed on krill, fish, squid, and other forms of sealife caught while swimming underwater. They spend about half of their life on land and half in the oceans.

Although all penguin species are native to the southern hemisphere, they are not found only in cold climates, such as Antarctica. In fact, only a few species of penguin live so far south. Several species are found in the temperate zone, and one species, the Galápagos Penguin, lives near the equator.

The largest living species is the Emperor Penguin (Aptenodytes forsteri): adults average about 1.1 m (3 ft 7 in) tall and weigh 35 kg (75 lb) or more. The smallest penguin species is the Little Blue Penguin (also known as the Fairy Penguin), which stands around 40 cm tall (16 in) and weighs 1 kg (2.2 lb). Among extant penguins larger penguins inhabit colder regions, while smaller penguins are generally found in temperate or even tropical climates (see also Bergmann's Rule). Some prehistoric species attained enormous sizes, becoming as tall or as heavy as an adult human (see below for more). These were not restricted to Antarctic regions; on the contrary, subantarctic regions harboured high diversity, and at least one giant penguin occurred in a region not quite 2,000 km south of the Equator 35 mya, in a climate decidedly warmer than today.

Penguins seem to have no special fear of humans and have approached groups of explorers without hesitation. This is probably on account of there being no land predators in Antarctica or the nearby offshore islands that prey on or attack penguins. Instead, penguins are at risk at sea from predators such as the leopard seal. Typically, penguins do not approach closer than about 3 meters (10 ft) at which point they become nervous. This is also the distance that Antarctic tourists are told to keep from penguins (tourists are not supposed to approach closer than 3 meters, but are not expected to withdraw if the penguins come closer).

Shark

Sharks (superorder Selachimorpha) are a type of fish with a full cartilaginous skeleton and a highly streamlined body. They respire with the use of five to seven gill slits. Sharks have a covering of dermal denticles that protect their skin from damage and parasites and improve fluid dynamics. They have several sets of replaceable teeth.^[1] Sharks range in size from the small dwarf lanternshark, Etmopterus perryi, a deep sea species of only 17 centimetres (7 in) in length, to the whale shark, Rhincodon typus, the largest fish, which grows to a length of approximately 12 metres (39 ft) and which feeds only on plankton, squid, and small fish through filter feeding.

The bull shark, Carcharhinus leucas, is the best known of several species that swim in both seawater and freshwater, as well as in deltas.

Lifespan

The maximum lifespan of a shark varies from species to species. Most sharks live for 20 to 30 years, while the spiny dogfish lives a record lifespan of more than 100 years. Whale sharks (Rhincodon typus) have been hypothesized to also live over 100 years.

Sea Horse

...are a genus (Hippocampus) of fish belonging to the family Syngnathidae, which also includes pipefish and leafy sea dragons. There are over 32 species of seahorse, mainly found in shallow tropical and temperate waters throughout the world. They prefer to live in sheltered areas such as sea grass beds, coral reefs, or mangroves. Colonies have been found in European waters such as the Thames Estuary.^[2] From North America down to South America there are approximately four species, ranging from very small in size (dwarf seahorses are only about an inch long) to those much larger, found off the Pacific Coast of Central America (the foot-long Hippocampus ingens). Hippocampus erectus are larger seahorses found anywhere from Nova Scotia down to around Uruguay. These fish form territories, with males staying in about one square meter of their habitat while females range about one hundred times that area. They bob around in sea grass meadows, mangrove stands, and coral reefs where they are camouflaged by murky brown and grey patterns that blend into the sea grass backgrounds. During social moments or in unusual surroundings, seahorses turn bright colors.

The beautiful colored seahorses belong to the most magnificent and most remarkable organisms of the seas. Actually a seahorse is quite normal fish, coming along only in a very special dress. There are about 35 different species of seahorses spread all over the world, but only a small spectrum of this variety is frequently imported for aquarist purposes. While the smallest species, the dwarf seahorse, is just 1.5 inch in lenght, others achieve a body length up to 14 inch (giant seahorse).

Dolphins

...are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in seventeen genera. They vary in size from 1.2 m (4 ft) and 40 kg (90 lb) (Maui's Dolphin), up to 9.5 m (30 ft) and 10 tonnes (9.8 LT, 11 ST) (the Orca or Killer Whale). They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating fish and squid. The family Delphinidae is the largest in the Cetacea, and relatively recent: dolphins evolved about ten million years ago, during the Miocene. Dolphins are considered to be amongst the most intelligent of animals and their often friendly appearance and seemingly playful attitude have made them popular in human culture.

All dolphins are toothed whales belonging to the sub-order, odontocetes, of the order cetacea (see section on humpback whales for more information). As a group, dolphins are often referred to as "small" cetaceans, even though some of them are quite large, attaining lengths of over 20 feet. In addition, although the terms dolphins and porpoises are often used interchangeably, they really refer to two different types of animals.

Porpoises belong to the family Phocoenidae. They are generally smaller and more robust species. Most attain about 5-7 feet in length. Porpoises have no distinct beak, or rostrum. Their foreheads slope almost uniformly to the tip of their snout, and their teeth are spade-like in shape. The family Phocoenidae is rather small, and consists of only six members. There are no porpoises found in Hawaiian waters.

Dolphins belong to the family Delphinidae. Dolphins possess a distinct beak. Their teeth are conical in shape. Most species of dolphins are larger than porpoises, with the males usually being larger than the females. The family Delphinidae is the largest and most diverse family of the cetacean order and includes 26 living species. Several species of dolphins are found in Hawaiian waters.

sEa mAmmALs

I found some of these interesting topic about sea mammal and here are some that i have posted.

Elephant SealsMany people may recognize the elephant seal from television documentaries. It is a well-studied species. This site has information on life, size, habitat and more.

Seals and Seal Hunting; Facts and Myths Norwegian seal-hunting is restricted to two species of seal: the harp seal and the hooded seal. In the North Atlantic, the harp seal population alone numbers close to four million animals. Of these, approximately 900 000 are to be found in areas where Norwegians hunt for seal. The seal populations are growing.

Shetland Wildlife Pages: Seals (Hooded, Grey, Ringed, Bearded and Common.
The only undoubtedly native mammals in Shetland are two species of seal - the Grey Seal and Common Seal - and the cetaceans, many of which are pelagic and so are only scarce visitors to inshore waters.

Mediterranean Monk Seal
The Mediterranean Monk Seal is one of the worlds most endangered mammals. What chance is there of saving it from extinction?

Harbour Seals
This page includes a list of topics on many aspects of harbour seals.

Sea Lions

California Sea Lion
California sea lions, like other sea lions, are quick and agile swimmers. They use their pectoral flippers in an up-and-down motion to swim. Although California sea lions are not threatened or endangered, they can be affected by pollution and overfishing.
Walrus

Walruses
This site contains information on the physical characteristics of walrus as well as their habitat, feeding habits and migration patterns.

whale

Here are some of the interesting topic about the whales... try to read them...

Humpback Whale
Whales are marine mammals which are neither dolphins (i.e. members of the families Delphinidae or Platanistoidae) nor porpoises. Orcas (Killer Whales) and Pilot whales have "whale" in their name, though they are dolphins for the purpose of classification.

All cetaceans, including whales, dolphins and porpoises, are descendants of land-living mammals of the Artiodactyl order (even-toed ungulate animals). Both cetaceans and artiodactyl are now classified under the super-order Cetartiodactyla which includes both whales and hippopotamuses. In fact, whales are the closest living relatives of hippos; they evolved from a common ancestor at around 54 million years ago.[1][2] Whales entered the water roughly 50 million years ago.[3] Cetaceans are divided into two suborders:

The baleen whales are characterized by baleen, a sieve-like structure in the upper jaw made of keratin, which they use to filter plankton from the water. They are the largest suborder of whale.
The toothed whales have teeth and prey on fish, squid, or both. An outstanding ability of this group is to sense their surrounding environment through echolocation.
A complete up-to-date taxonomical listing of all cetacean species, including all whales, is maintained at the Cetacea article.

Whales are widely classed as predators, but their food ranges from microscopic plankton to very large fish. Males are called bulls; females, cows. The young are called calves.
As mammals, whales breathe air and must surface to get oxygen. This is done through a blowhole. Many whales also exhibit other surfacing behaviours such as breaching and tail slapping.

Because of their environment (and unlike many animals), whales are conscious breathers: they decide when to breathe. All mammals sleep, including whales, but they cannot afford to fall into an unconscious state for too long, since they need to be conscious in order to breathe. It is thought that only one hemisphere of their brains sleeps at a time, so that whales are never completely asleep, but still get the rest they need. This is thought because whales often sleep with only one eye closed.[citation needed]
Whales also communicate with each other using lyrical sounds, called whale song. Being so large and powerful, these sounds are also extremely loud (depending on the species); sperm whales have only been heard making clicks, as all toothed whales (Odontoceti) use echolocation and can be heard for many miles. They have been known to generate about 20,000 acoustic watts of sound at 163 decibels.[10]

Females give birth to a single calf. Nursing time is long (more than one year in many species), which is associated with a strong bond between mother and young. In most whales reproductive maturity occurs late, typically at seven to ten years. This mode of reproduction spawns few offspring, but provides each with a high probability of survival in the wild.

The male genitals are retracted into cavities of the body during swimming, so as to be streamlined and reduce drag. Most whales do not maintain fixed partnerships during mating; in many species the females have several mates each season. At birth newborn are delivered tail-first, minimizing the risk of drowning. Whale cows nurse by actively squirting milk the consistency of toothpaste into the mouths of their young preventing loss to the surrounding aquatic environment.