Oceans cover almost 3/4 of the Earth's surface and contain roughly 97% of the Earth's water supply. Life on Earth originated in the salty seas, and contines to be home to an incredibly diverse web of life.
The Earth's oceans are all connected to one another. There are five oceans: the Pacific, Atlantic, Indian, Arctic, and Southern. There are also many seas (smaller branches of an ocean); seas are partly enclosed by land. The largest seas are the South China Sea, the Caribbean Sea, and the Mediterranean Sea.
The Blue Whale (Balaenoptera musculus) is a marine mammal belonging to the suborder of baleen whales (called Mysticeti).[3] At up to 32.9 metres (108 feet) in length and 172 metric tonnes (190 short tons)[4] or more in weight, it is the largest animal ever to have existed.[5]
Long and slender, the Blue Whale's body can be various shades of bluish-grey dorsally and somewhat lighter underneath.[6] There are at least three distinct subspecies: B. m. musculus of the North Atlantic and North Pacific, B. m. intermedia of the Southern Ocean and B. m. brevicauda (also known as the Pygmy Blue Whale) found in the Indian Ocean and South Pacific Ocean. B. m. indica, found in the Indian Ocean, may be another subspecies. As with other baleen whales, its diet consists almost exclusively of small crustaceans known as krill.[7]
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.
The killer whale or orca (Orcinus orca), less commonly, blackfish or seawolf, is the largest species of the dolphin family. It is found in all the world's oceans, from the frigid Arctic and Antarctic regions to warm, tropical seas. Killer whales are versatile and opportunistic marine apex predators. Some populations feed mostly on fish while others hunt marine mammals, including sea lions, seals, walruses and even large whales. There are up to five distinct killer whale types distinguished by geographical range, preferred prey items and physical appearance. Some of these may be separate races, subspecies or even species.[3] Killer whales are highly social; some populations are composed of matrilineal family groups, which are the most stable of any animal species.[4] The sophisticated social behavior, hunting techniques, and vocal behavior of killer whales have been described as manifestations of culture.[5]
Although the killer whale population as a whole is not considered to be an endangered species, some local populations are considered threatened or endangered due to depletion of prey species and habitat loss, pollution by PCBs, captures for marine mammal parks, and conflicts with vessels. In late 2007, the killer whales known as the "southern resident killer whales," were placed on the U.S. Endangered Species list. [6][7][8]
Wild killer whales are usually not considered a threat to humans.[9] There have, however, been isolated reports of captive killer whales attacking and, in at least one instance, killing their handlers at marine theme parks.[10][11] There is also a level of confusion surrounding the term "whale". While killer whales are members of the dolphin family, they, and all other members of the dolphin family, are members of the sub-order Odontoceti and the order Cetacea, meaning "toothed whale" and "whale", respectively.
Jellyfish (also known as jellies or sea jellies) are free-swimming members of the phylum Cnidaria. They have several different morphologies that represent several different cnidarian classes including the Scyphozoa (over 200 species), Staurozoa (about 50 species), Cubozoa (about 20 species), and Hydrozoa (about 1000-1500 species that make jellyfish and many more that do not)[1][2]. The jellyfish in these groups are also called, respectively, scyphomedusae, stauromedusae, cubomedusae, and hydromedusae; medusa (plural medusae) is another word for jellyfish. (Medusa is also the word for jellyfish in Modern Greek, Finnish, Portuguese, Romanian, Hebrew, Serbian, Croatian, Spanish, French, Italian, Hungarian, Polish, Czech, Slovak, Russian and Bulgarian.) !
Jellyfish are found in every ocean, from the surface to the deep sea. Some hydrozoan jellyfish, or hydromedusae, are also found in fresh water. Most of the information about jellyfish that follows in this article is about scyphozoan jellyfish, or scyphomedusae. These are the large, often colorful, jellyfish that are common in coastal zones worldwide.
In its broadest sense, the term jellyfish is sometimes used also to refer to members of the phylum Ctenophora. Although not closely related to cnidarian jellyfish, ctenophores are also free-swimming planktonic carnivores, are also generally transparent or translucent, and occur in shallow to deep portions of all the world's oceans
The octopus (pronounced /ˈɒktəpəs/, from Greek ὀκτάπους (oktapous), "eight-footed",[3][4] with plural forms: octopuses /ˈɒktəpʊsɪz/, octopi /ˈɒktəpaɪ/, or octopodes /ɒkˈtɒpədiːz/, see below) is a cephalopod of the order Octopoda that inhabits many diverse regions of the ocean, especially coral reefs. The term may also refer to only those creatures in the genus Octopus. In the larger sense, there are around 300 recognized octopus species, which is over one-third of the total number of known cephalopod species.
An octopus has eight arms, which trail behind it as it swims. Most octopuses have no internal or external skeleton, allowing them to squeeze through tight places. An octopus has a hard beak, with its mouth at the center point of the arms. Octopuses are highly intelligent, probably the most intelligent invertebrates. For defense against predators, they hide, flee quickly, expel ink, or use color-changing camouflage. Octopuses are bilaterally symmetrical, like other cephalopods, with two eyes and four pairs of arms. All octopuses are venomous, but only the small blue-ringed octopuses are deadly to humans.[5]
hope that helps
by:bube07
and sorry i cant create pictures on any post