Tursiops truncatus
The bottlenose dolphin, turson or bottlenose dolphin (Tursiops truncatus) is a species of toothed cetacean in the Delphinidae family. Of the more than 30 species of dolphins that exist, it is the most common and best known of the family. This is because it is often kept in captivity, as its sociable nature and intelligence make it the star of many shows.
In the wild, these dolphins live in groups of up to 10 or 12 individuals. Like other dolphins, they use an echolocation system to locate their food and often cooperate with each other to corner their prey. They frequently ply the wake left by boats and sometimes approach swimmers and let them play with them.
They inhabit warm and temperate seas around the world and can be found in all oceans except the Arctic and Antarctic.
Behavior and life
Bottleneck dolphins swim at a speed of 5-11 km/h (3-6 knots); in short times they can reach top speeds of 35 km/h (21 knots).
Every 5-8 minutes, dolphins have to surface to breathe through their blowhole (on average they breathe more often). His sleep is thus very light; some scientists have suggested that the two halves of their brains take turns sleeping and waking up.
Bottleneck dolphins normally live in groups called pods, containing up to 12 animals; these are long-term social units. Typically, a group of females and their young live together in a pod, and juveniles in a mixed pod. Several of these pods can constitute larger pods of hundreds of dolphins or more. Males only live in groups of 2-3 and join pods for short periods of time.
The species is known for its friendly nature and curiosity. It is common for a diver to be investigated by a group of them. From time to time, dolphins have rescued endangered divers by bringing them to the surface, a behavior they also display toward endangered members of their own species. In November 2004, a more dramatic report of dolphin involvement came from New Zealand: a great white shark approached three lifeguards, swimming 100m offshore near Whangarei. A pod of dolphins, apparently sensing the danger from the swimmers, gathered and tightly circled them for forty minutes, preventing a shark attack.
Dolphins are predators, so they also display aggressive behavior. This includes fights between males for access to females, as well as attacks on sharks and other smaller species of dolphins. Males reach sexual maturity at 11 years; females, at 12. The mating season is usually in spring. Male dolphins, during the mating season, compete very vigorously with each other to demonstrate their strength and size.
Gestation lasts about 11-12 months; Usually, they have a young, which usually measures 1-1.5 m and weighs between 30 and 40 kg. They stop every 2-3 years. The suckling period lasts between 12-18 months.
Female bottlenose dolphins live for about 40 years; the more strenuous life of the males apparently takes its toll, and they rarely live more than 30 years.
Diet
The diet is coastal and based mainly on a variety of fish and invertebrates from littoral and sublittoral zones, while mesopelagic fish and oceanic squid are commonly found in the diet of those far from shore. The diet also varies with the local availability of the prey.
Senses and communication
Dolphins' search for food is aided by a form of echolocation, similar to sonar: they locate objects by making sounds and listening for the echo. These sounds are clicks that are emitted in a column focused towards the front of the animal. They have two small ear openings behind their eyes, but most sound waves are transmitted to the inner ear through the lower jaw. As the object of interest approaches, the echo grows louder; the dolphins then adjust by lowering the volume of the emitted sounds (this is in contrast to the technique used by stick echolocation and human sonar: here the receiver's sensitivity to the sounds is decreased.)
They also have keen eyesight. The eyes are situated on the sides of the head and have a tapetum lucidum which helps in dim light conditions. On the contrary, their sense of smell is very poor.
Botnose dolphins communicate with body movements and sounds, which they produce with six air sacs near their blowhole (they lack vocal cords). Each animal has a characteristic signature sound with which it identifies itself to others. Other communication uses about 30 distinguishable sounds, of course there is no larynx. (See also the Dolphin Brain article for background information on dolphin intelligence.)
Behavior
The dolphins form small groups that do not exceed the average of 12 specimens. The social system of this species is quite complex and is called a fission-fusion society since its individuals associate in small groups that change their composition in short periods (days or even hours). Several subgroups can unite to thus form larger associations.
Botnose dolphins studied by biologists at the BDRI Institute for the Study of Bottlenose Dolphins in Sardinia show particular associations during feeding depending on the abilities of each partner. These bottlenose dolphins have changed their habits since the creation of an aquaculture nursery in the area.
Bottlenose dolphins also interact with other human activities such as inshore netting and trawling trying to get the food left in the nets. This interaction has a clear negative effect in the form of accidental catches of dolphins that remain entangled in fishing nets.
According to researchers at the Institute for the Study of Bottlenose Dolphins BDRI, familiarizing dolphins with the high presence of recreational boats in our waters "has obvious survival value," as acclimatization it allows the mammal to ignore stimuli without any relevant biological information and minimizes energy expenditure in flight when ships approach. In this way, the dolphins can focus more on finding prey to feed on. However, the accommodation of these animals to human presence, such as chimpanzees or gray whales, may pose a risk to their survival. According to experts, the "lack of caution" towards humans, even in "benign relationships", can cause solitary and sociable dolphins "serious injury or death".
Intelligence
It has been confirmed that bottlenose dolphins are the second most intelligent animal on the planet, after humans and ahead of the great apes, contradicting what was previously believed. Some characteristics that define the intelligence of these cetaceans are:
- Big brain in proportion to the body, with a size greater than humans.
- The existence of a language of snuffs and whistles, whose exact accuracy is unknown.
- Self-recognition in a mirror (proof of the mirror).
- Ability to learn a language of simple gestures, through which they can obey orders.
- Use of tools: the females use sponges to cover the black and protect themselves when eating. This tradition, which is transmitted from mothers to daughters, indicates that there is a certain culture among the mule dolphins.
Bottleneck dolphins can be trained for a variety of purposes. The United States Navy trains them to detect mines, protect facilities, and attack enemies, among other things. The most famous of all is K-dog (pictured).
Subspecies
- Tursiops truncatus truncatus
- Tursiops truncatus ponticusIt's the black sea dolphin. He's threatened.
- Tursiops truncatus gephyreous known as "Tonina", lived on the Argentine coast from Samborombón Bay to Chubut. It is estimated that about 400 copies remain in 2019. In his honor, the coastal town of Las Toninas was named because at the beginning of the XX, specimens could be observed from the coast of the town.