Oceanic dolphin

Oceanic dolphins are a widely distributed family of fully aquatic marine mammals. The oceanic dolphins comprises the family Delphinidae. There are 30 extant species of oceanic dolphins. Dolphins, alongside othercetaceans, belong to the clade Cetartiodactyla with even-toed ungulates, and their closest living relatives are the hippopotamuses, having diverged about 40 million years ago.

Oceanic dolphins range in size from the 1.7 m long and 50 kg Maui's dolphin to the 9.4 m and 10.0 t killer whale, the largest known dolphin. Several species exhibit sexual dimorphism, in that the males are larger than females. They have streamlined bodies and two limbs that are modified into flippers. Though not quite as flexible as seals, some dolphins can travel at 34.5 miles per hour (55.5 km/h). Most delphinids primarily eat fish, along with a smaller number of squid and small crustaceans, but some species specialise in eating squid, or, in the case of the killer whale, also eat marine mammals and birds. All, however, are purely carnivorous. They typically have between 100 and 200 teeth, although a few species have considerably fewer. Delphinids travel in large pods, which may number a thousand individuals in some species. Each pod forages over a range of a few dozen to a few hundred square miles. Some pods have a loose social structure, with individuals frequently joining or leaving, but others seem to be more permanent, perhaps dominated by a male and a harem of females. Individuals communicate by sound, producing low-frequency whistles, and also produce high-frequency broadband clicks of 80-220 kHz, which are primarily used for echolocation. Gestation lasts from 10 to 18 months, and results in the birth of a single calf. Some species are well adapted for diving to great depths. They have a layer of fat, or blubber, under the skin to keep warm in the cold water.

Shark

harks are a group of fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the cladeSelachimorpha (or Selachii) and are the sister group to the rays. However, the term "shark" has also been used for extinct members of the subclass Elasmobranchii outside the Selachimorpha, such as Cladoselache andXenacanthus, as well as other Chondrichthyes such as the holocephalid eugenedontidans. Under this broader definition, the earliest known sharks date back to more than 420 million years ago. Acanthodians are often referred to as "spiny sharks"; though they are not part of Chondrichthyes proper, they are a paraphyletic assemblage leading to cartilaginous fish as a whole.

Since then, sharks have diversified into over 500 species. They range in size from the small dwarf lanternshark (Etmopterus perryi), a deep sea species of only 17 centimetres (6.7 in) in length, to the whale shark(Rhincodon typus), the largest fish in the world, which reaches approximately 12 metres (39 ft) in length. Sharks are found in all seas and are common to depths of 2,000 metres (6,600 ft). They generally do not live in freshwater although there are a few known exceptions, such as the bull shark and the river shark, which can survive and be found in both seawater and freshwater. Sharks have a covering of dermal denticles that protects their skin from damage and parasites in addition to improving their fluid dynamics. They have several sets of replaceable teeth.

Well-known species such as the great white shark, tiger shark, blue shark, mako shark, and the hammerhead shark are apex predators—organisms at the top of their underwater food chain. Many shark populations are threatened by human activities.

Giant squid

The giant squid (genus Architeuthis) is a deep-ocean dwelling squid in the family Architeuthidae. Giant squid can grow to a tremendous size due to deep-sea gigantism: recent estimates put the maximum size at 13 m  for females and 10 m  for males from the posterior fins to the tip of the two long tentacles (second only to the colossal squid at an estimated 14 m , one of the largest living organisms). The mantle is about 2 m  long (more for females, less for males), and the length of the squid excluding its tentacles (but including head and arms) rarely exceeds 5 m . Claims of specimens measuring 20 m  or more have not been scientifically documented.

The number of different giant squid species has been debated, but recent genetic research suggests that only one species exists.

In 2004 Japanese researchers took the first images of a live giant squid in its natural habitat, and in July 2012 a live adult was first filmed in its natural habitat off Chichi-jima.

Giant oarfish

The giant oarfish (Regalecus glesne), also called the king of herrings, is a species of oarfish of the family Regalecidae. It is an oceanodromous species with a worldwide distribution, excluding polar regions.

R. glesne is the world's longest bony fish. Its shape is ribbon-like, narrow laterally, with a dorsal fin along its entire length, stubby pectoral fins, and long, oar-shaped pelvic fins, from which its common name is derived. Its coloration is silvery with dark markings, and its fins are red. Its physical characteristics and its undulating mode of swimming have led to speculation that it might be the source of many "sea serpent" sightings.

The body of ribbon-like forms, with a length of 3.5 m height of the trunk can be up to 25 cm and its thickness - only 5 cm; extra long 5.5 m weighs about 250 kg. The head is very short, mouth small, with a vertical slit mouth, pull. The dorsal fin is very long, starts on the head above the eye and extends to the rear end of the body. The dorsal fin has soft rays of 300-400, including 10-15 greatly elongated front, equipped with membranous extensions to the top and form a color Sultan. Pectoral fins short, horizontal. Pelvic fins thoracic (located below the chest), represented by a single long beam, paddle-shaped flattened at the end. The caudal fin in adults rudimentary fish, young fish presented several long free rays. Body without scales, covered with bony tubercles (bumps), grouped in longitudinal rows. The lateral line is long, takes place in the lower part of the body. The swim bladder is absent.

Hammerhead shark

The hammerhead sharks are a group of sharks in the family Sphyrnidae, so named for the unusual and distinctive structure of their heads, which are flattened and laterally extended into a "hammer" shape called a cephalofoil. Most hammerhead species are placed in the genus Sphyrna while the winghead shark is placed in its own genus, Eusphyra. Many not necessarily mutually exclusive functions have been proposed for the cephalofoil, including sensory reception, maneuvering, and prey manipulation. Hammerheads are found worldwide in warmer waters along coastlines and continental shelves. Unlike most sharks, hammerheads usually swim in schools during the day, becoming solitary hunters at night. Some of these schools can be found near Malpelo Island in Colombia, Cocos Island off Costa Rica, and near Molokai in Hawaii. Large schools are also seen in the waters off southern and eastern Africa.

Fish-Eagle

Fish-Eagle is represented in nature multiple births, the total number of species reaches 150. The most numerous are born Syngnathus, ie Fish ordinary needle. They present the tail and pectoral fins, and the body has a hexagonal shape in front of and in back of the tetrahedral. In total there are more than 50 species of this genus.

Similar cerate (Fish-lantern)

Deep-sea anglers constantly live at great depths, 1500-3000 m deep in the ocean waters. They are characterized by spherical, flattened laterally body shape and the presence of "rod" (in females). From other anglerfish they are distinguished by the absence of pelvic fins. Skin camouflage colors - black or dark brown, naked; several species covered transformed scales - spines and plaques. Traditionally, the appearance is a deep sea fish are bloated body with bulging eyes and ugly forms. In fact it's not. Kind of bloated bodies deep sea fish take when picked up on the surface in fishing nets, due to excessive internal pressure, which is at a depth of 1500-3000 meters values ​​of 150-300 atmospheres.