Odontoceti

The odontocètes ( Odontoceti ), or Cetacea with Dent S ( whales with teeth ) constitute one of both sub-orders Cétacé S with the Mysticète S (or Baleine S with pennons).
The Cetacea of this species have teeth, whereas mysticètes is Cetacea with pennons. The odontocètes are the only animals with the bats and certain shrews capable of echolocation by means of Ultrason S: they locate their preys and are directed by analyzing the echoes of the sounds which they emit. A function which is connected with the system of the Sonar. The sub-order of the odontocètes includes/understands the various species of Beluga S, of Cachalot S, Orque S (or épaulards), of Dauphin S, Marsouin S, Narval S and Globicéphale S.

Community life

Many species are Social are. They form groups of individuals with a social structure complexes, collaborating for the Chasse and mutual defense.

Animals very intelligent

Many experiments in cognitive ethology showed their large Intelligence. One considers the capacities mental of a dolphin or an orc adult equivalent to that of a two year old child .

They can be recognized when one places them in front of a mirror within the framework of the Test of the mirror of Gallup. At present, separately the dolphins, this capacity was observed only at the human , some Singe S and the elephant S. This suggests that these animals are aware of themselves.

One also recently observed dolphins make use of tools, fact exceptional which had been observed hitherto only at some species of Grands monkeys. Thus, of the dolphins were observed use sponges of sea to protect the muzzle when they scrape sea-bed. Since, it was shown that this technique was transmitted by training of the mothers to the girls.

Delphinés are one of the rare species which also practice the sex for the pleasure, without intention of procreation .

It is considered that they represent a case of evolutionary Convergence with the primates and in particular, the Hominidé S, for their great capacities Cognitive S in comparison with the others Taxon S of Marine mammals.

Language

Their language based on noisy whistles and inaudible Ultra-son S for the human ear seems to be very elaborate but is still badly included/understood. The studies undertaken with large dolphins showed that they were able to identify the " voix" various individuals of their group.

Threats

Although almost unanimously appreciated by the Man, the odontocètes are confronted with increasing threats:
  • the Pollution of the oceans and contamination of the trophic networks with the head of which they are nourished. With the Tuna S, the Swordfish S, the Cachalots they are the marine animals which contain the most Heavy metals, of Dioxine S and residues of Pesticide S. Their flesh which is still consumed with the Japan present of the contents of toxic metals exceeding and often much international standards and main roads. Their only mercury content would theoretically be enough to make some prohibit consumption in the majority of the cases;
  • the disappearance of part of their food because of overexploitation of the oceans by the Man is one second threat;
  • the wounds, asphyxiations or the stress by accidental captures in the trawls or drifting gill nets cause the death of many dolphins every year;
  • the Cetacea scrape themselves sometimes on the bottom on rocks or hard objects to be cleaned the skin or to remove from parasites, one can fear that they are in increasingly frequent contact with immersed ammunition or that they are poisoned by their food in the zones where ammunition or other waste were immersed;
  • one also evokes since ten year the increasingly frequent use of sounders and Sonar S civilians or soldiers or underwater explosions with vocation of detection of oil resources for example which could affect their auditive system and of echolocation, and perhaps to explain certain strandings in series;
  • it could be that the universalization of the exchanges diffuse also microbes suitable for affect the Cetacea, of which the flu virus to which they are sensitive.

A remarkable anatomy

With equal weight, the dolphin is six times stronger than the man . Nevertheless, its force does not seem to be the independent factor which explains its speed of stroke. When it moves in water, it creates if few Turbulence S which the hydrodynamic force of resistance is reduced to its minimum. This comes not only from its way of swimming which does not generate turbulences, but still remarkable properties of its skin. The skin of the dolphin rests on a multitude of small elastic bearings which deaden the shocks.

In diving, the palpitations of the dolphin slow down half, and only the vital brain, heart and other bodies are oxygenated, which decreases the need for air. The dolphin can at will empty its lungs of 90% of their contents, contrary to the man. The residual nitrogen is absorbed by an emulsion produced in the lungs, then eliminated without damage when the animal goes back to surface. Lastly, the flexibility of the rib cage of the dolphin enables him to withstand crushing pressures.

Its kidneys are designed for the oceanic medium and can eliminate as much from salt than necessary, which makes it possible this animal to drink with impunity sea water.

The dolphin avoids the obstacles thanks to a system of echolocation, or Sonar. The animal emits a series of whistles or high frequency clappements, then it analyzes the echo produced by these signals which rebound on the obstacles, which enables him to determine the nature and the distance from these objects. As these animals do not have an olfactive body, they cannot recognize food with the odor, also their sonar their is vital.

Classification

The sub-order contains 6 families:

More 4 optional families:

Anatomy

The odoncètes are carnivorous. Their teeth are not used to them to chew but catch their preys, which are composed of Poisson S, Calmar S, Mollusque S and sometimes of other Cetacea for large predatory the odontocètes such as the orcs (also called épaulards). Certain species such as the whales with nozzles or the cachalots have teeth only on the jaw lower. Like all the Mammalian S sailors, the odoncètes have lungs and must periodically breathe on the surface. The odontocètes have one vent what distinguish them from the whales with pennons.

See too

Related articles

  • History of the Cetacea

External references

  • Site of information on the Cetacea

Zh-min-nan: Khí-keng Zh-yue: 齒鯨亞目

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