(06-07-10) It is thought to be one of the most intelligent and beautiful creatures of our oceans and rivers, but dolphins also have a personality that is loved worldwide. We see them jumping, playing and even we hear them laughing while they have fun in the ocean. Dolphins are one of the most intelligent creatures on earth.
These warm-blooded mammals belong to the group of cetaceans, which include all whales. Dolphins are also known as “toothed whales” or toothed cetaceans, different from Baleen whales, which have sieve-like structure called baleen that catches huge amounts of tiny krill for nourishment.
Dolphins are of different colours, from white (like orcas) to black (false killer whales and right whales). There are 70 dolphin species: 33 live in oceans, and the rest live in rivers, or are sperm whales, belugas, narwhals, beaked whales and porpoises.
Porpoises are often confused with dolphins, but dolphins’ teeth are rounded and porpoises’ are square. Bottlenose dolphins (Tursiops truncatus) are the species more common seen in Spanish waters.
Bottlenose dolphins live in warm and tropical waters worldwide, from deep ocean waters to ports, bays, lakes, gulfs and estuaries. In general, coastal dolphins seem to be adapted to warm and shallow waters. Their bodies are smaller and fins are longer, which show more manoeuvrability and heat dissipation.
Dolphins that live offshore seem to be adapted to colder and deeper waters, their bodies are longer, which helps them to keep heat and defend themselves from predators. Variations in water temperature, migration of fish food and eating habits are considered for seasonal movements of some dolphins to certain areas and from certain areas in the autumn months.
Dolphins can be born tail or head. “Uncles” and “aunts” can attend the birth and they are the only to be with the newborn. Dolphins have a quite close relationship with offspring for a long time of parental care during maturing.
Dolphins are birthed, like most mammals, through the birth canal into the abdomen of the female. Generally there is only one offspring. When a dolphin is born, it goes to the surface helped by the mother for the first breath. It is breastfed on the surface while the mother turns aside to let the baby breathe easily while eats.
The newborn is breastfed to the 18 month generally, while the milk, approximately 33% fat, helps the baby establish a thick layer of fat that serves as insulation. The rapid growth of the baby dolphin is related largely to the high fat, calcium and phosphorus that the mother's milk has.
In captivity, offspring can begin to eat some fish from the 90 to 120 days. The mother-offspring bonds are long-lasting with offspring that remain with their mothers for 3-6 years or more. A baby bottlenose dolphin is a little over a meter at birth, and can grow to be 3 meters. The gestation period is 10 to 17 months.
A LONG AND FULL FAMILY LIFE
Dolphins live in groups, called herds. They are social units consistent in the long term that vary in size and structure, although their composition is based mainly in age, sex and reproductive condition. Many herds consist of the mother and pairs of offspring and herds of mature females and newborns; others are mixed females and males; and there are also herds of only females or only males.
It has been observed that some adult males are alone, in pairs or occasionally in groups of three, moving among groups of females that have the same age and mating with females for short periods. Adult males are seldom associated to sub adult males.
Is this familiar to you? Many times different herds join for short periods of time to form groups of hundreds specimens. This is frequently seen in hour bays all year round. Groups of any size and social hierarchy can be observed in bottlenose frequently.
The census data from several conservation organizations and scientific studies of dental materials suggest that the average life of a bottlenose dolphin is 23 years or less. While they are not endangered, it is important for all of us to help preserve this beautiful creature.
THEIR PREDATORS ARE SHARKS AND HUMAN BEINGS
Their predators are different species: sharks, orcas and diseases caused by bacteria or parasites. Pollution and bycatch are also risk factors and cause death to a lot of dolphins in fishing areas. Many conservation organizations are making efforts to prevent this kind of ecological disaster.
Bottlenose dolphins can be met “surfing” near the bow of a ship. They do this to “take a walk” in currents pushed forward by the boat and it is considered of good luck by sailors worldwide.
Bottlenose dolphins can swim at cruising speeds between 5 and 15 km/h for short periods of time. Although these dolphins do not need to dive very deep to get food, they usually dive to depths of 50 meters.
The maximum depth a trained dolphin has reached was registered to be 547 meters. These mammals can dive from 8 to 10 minutes and keep heart beating slowly while they dive to diminish oxygen in the body.
Dolphins are very good acrobats and can be seen making complex aerial and clever manoeuvres that amaze viewers, marine parks and in the wild. They can execute spins and flips that lead them out of the water during mating, like hierarchical domain demonstrations or just when they want to be playful.
DOLPHIN, MORE THAN A FRIEND
More than a fascinating marine creature and a mammal like us, dolphin and human beings have a history of positive interaction one to each other. Dolphins routinely interact with swimmers and divers in a very playful way, swimming very close, poking around and even offering rides when a person gently grabs their dorsal fin.
They are very nice and there are stories about dolphins helping sailors that have fallen overboard, swimmers and people injured while they were surfing. It is always funny to have dolphins around when one swims, dives or practice snorkel, with their cheerful and playful personalities, creating a happy and memorable spectacle. Also, with increasing frequency, they are being used in aquatic therapies, in which they get very positive results.
Text:
Guadalupe Romero / elportaldelosbarcos |
