Bottlenose dolphin: what is it?

Bottlenose dolphin (Montagu 1821) – Tursiops truncatus

• Order : Cetacea
• Suborder : Odontoceti
• Family : Delphinidae
• Subfamily : Delphininae
• Gender : Tursiops
• Cut : 2.00 and 3.00 meters
• Weight : 200 to 300 kg
• Longevity : 30 to 40 years

Conservation status IUCN : DD insufficient data

Description of the bottlenose dolphin

the bottlenose dolphin is thespecies the best known both scientifically and by the general public thanks to the television series Pinball the Dolphin. It is distinguished from others thanks to its characteristic “smile” due to the folds of its rostrum. The bottlenose dolphin has a fusiform body adopting more or less light or dark gray tints on the dorsal part, and white on the belly. The color is paler on the sides. His forehead is adorned with a melon which houses the system of sonar orecholocation. the beak is short and wide. The dorsal fin is triangular and curved in the shape of a scythe. The pectoral fins are quite small and also triangular, while the caudal fin, whose average width is about 60 cm, is divided into two lobes.

Bottlenose dolphin habitat

The distribution of the bottlenose dolphin is wide, as it occupies all the temperate and tropical seas of the globe. It is absent from the polar regions arctic and Antarctica. Populations occupy different niches. Some are coastal while others are pelagic. Some frequent the estuaries, bays or lagoons. As a general rule, the bottlenose dolphin shows a predilection for warm waters whose depth does not exceed 30 meters.

Bottlenose dolphin behavior

Coastal populations are migratory, while conversely, open sea populations are sedentary. The bottlenose dolphin is a social animal that lives in small family groups usually consisting of two to six individuals, but larger troops have been observed. Some individuals live near large cetaceans. Dolphins in oceanic populations can dive more than 200 meters deep and stay in apnea for about fifteen minutes, while those of the coastal populations only exceptionally pass the 30-meter mark, with dives of four to five minutes. The speed cetaceans can reach 30 km/h.

The bottlenose dolphin performs acrobatics out of the water whose meaning is still not clearly established. These have been listed as follows:

• the full jump out of the water;
• walking backwards on the water using the tail as a fulcrum;
• hitting the water with the caudal fin;
• the vertical jump totally out of the water;
• the slips on the waves created by the ships;
• jumping out of the water and falling flat on the back.

Vocalizations consist of clicks which are high frequency sounds, whistles and barks. They are used to communicate between individuals, to signal a source of food or danger, or even during courtship displays.

The bottlenose dolphin is a predator that frequently adopts aggressive behavior. It is able to fight against another male to win a female, but also when it enters into food competition with the porpoise. He does not hesitate to attack and kill. Populations living along the coasts of Scotland seem to practice infanticide.

Reproduction of the bottlenose dolphin

Births take place during the season summer after a twelve-month gestation. As a general rule, the female gives birth to only one young every two or three years, but sometimes there are two. At birth, the dolphineau measures one meter. As with other delphinids, the mother is helped by other females when farrowing, which bring the newborn to the surface so that it can breathe. The young dolphin is weaned after eighteen months before the next birth. Females reach sexual maturity between 6 and 12 years old, while males are able to reproduce between 10 and 13 years old.

Bottlenose dolphin diet

The bottlenose dolphin feeds mainly on Pisces : sardines, anchovies, mullet, mackerel…, but it is an opportunistic cetacean which does not disdain cephalopods and the shellfish. The animal hunts by cooperating with other conspecifics to encircle the school of fish they covet, or practices the dangerous method of grounding which is a tactic similar to that of the killer whale. They push prey back onto the beach and feed on it by partially emerging from the water. This method can only be performed by tide high to prevent the dolphin from getting stuck on the shore.

Threats to the bottlenose dolphin

Although the populations seem important, the threats weighing on the bottlenose dolphin are of several natures. There is hunting for its meat or because it competes with Man for sincatches for dolphinariums (it is the cetacean that best tolerates captivity), pollution in metals heavy loads, the increase in maritime traffic, the reduction of its space due to the urbanization of the coasts and nuisance they cause, and the noise pollution because of the discomfort it can cause to the animal’s orientation system. They are obviously also victims of drifting or dragging nets.

The case of catches to supply dolphinariums has recently reached a peak of greed and bad faith. We already knew that a large hotel in Las vegas created a park lions in the name of the preservation of the species, but a luxury hotel in Singapore with a casino, had 25 dolphins captured to show them off to its customers! Their pseudo-ecological approach is simply outrageous because the planned gigantic basin will house 700,000 marine species in the name of preserving marine life. This same group had already been noticed for having wanted to capture a whale shark, but this megalomaniac project failed thanks to the intervention of environmental groups and an international petition.

Did you know ?

L’intelligence of the bottlenose dolphin and his affection for humans is well known. But here again, Man abuses this friendship by using the animal as an auxiliary in military operations (detection of floating mines, recovery of mines or torpedoesdetection ofcomputers of flight or heads of rocket…).

Fortunately, other interactions are more peaceful, such as dolphin therapy. The dolphin is used to interact with children or adults, in cases ofautism or deep depression.