One of the most intelligent and beautiful creatures in our oceans and rivers, dolphins are universally adored. We see them playfully jump and even hear them laugh as they frolic in the ocean. These warm-blooded animals belong to a group of mammals called Cetaceans, which also includes whales. Dolphins, referred to as "toothed whales" or Odontocetes, are different from baleen whales, which have horny plates connected to their upper jaw.
From the black and white killer whale (actually in the dolphin family) to the solid black false killer whale and pilot whale, dolphins vary in color. Thirty-two of the 67 total species of dolphins are oceanic; the remaining 35 species are river dolphins, sperm whales, beaked whales, beluga, narwhal and porpoises. Although porpoises are often confused with dolphins, their teeth are squared while dolphins have cone-shaped teeth. Pacific bottlenose dolphins (Tursiops Truncatus) are the variety most commonly observed in and around the Banderas Bay area.
Migration and Distribution
Bottlenose dolphins inhabit temperate and tropical waters throughout the world--from deep ocean waters to harbors, bays, lagoons, gulfs and estuaries. The coastal ecotype, one of the two types of bottlenose dolphins, seems to be adapted for warm, shallow waters. Its smaller body and larger flippers suggest increased maneuverability and heat dissipation. In contrast, the offshore ecotype seems to be adapted for cooler, deeper waters with a larger body that helps conserve heat and defend against predators. Some coastal animals stay within a limited home range (an area in which they regularly move about during day-to-day activities). Home ranges may overlap, and most dolphins undergo seasonal movements, probably as a response to variations in water temperature and migration of food fish. ?? Although the overall population of bottlenose dolphins is unknown, specific bottlenose dolphin populations have been approximated in a few areas, and based on those calculations, their population worldwide is estimated to be near 1 million. Bottlenose dolphins are not endangered, but laws in many countries protect them.
On the west coast of Mexico calving generally happens in the fall months. Deliveries can be either tail or head first. "Auntie" dolphins, either male or female, may assist with the birth and are often the only other dolphin allowed near the calf. Dolphins have a close parental relationship with their offspring, providing care through maturation. Dolphins are birthed like most mammals via the birth canal in the female abdomen, generally resulting in a single offspring. ?? When a new baby dolphin is born, with its mother's help it immediately heads for the surface of the water for its first breath. It is nursed on the surface as the mother turns on her side to allow the calf to breathe easily while nursing.
The baby will generally nurse for up to 18 months, and the milk, which is about 33% fat, helps the calf establish a thick layer of blubber for insulation. The rapid growth of the baby dolphin is related largely to the high fat, calcium and phosphorus content of the mother's milk. In zoological environs calves can start to take a few fish at about 90 to 120 days. Mother-calf bonds are long lasting with calves staying with their mothers 3 to 6 years or more. An average bottlenose dolphin calf is a little over 3 feet at birth and can grow to eight or nine feet long.
Where am I?
Although the dolphins have large eyes located near the corners of their mouths with acute vision both in and out of the water, they locate most of their food with echolocation. The term echolocation refers to an ability to "see" with their ears by listening for echoes. Dolphins echolocate by producing a clicking sound and then receiving and interpreting the resulting echo. Dolphins produce directional clicks in trains. Each click lasts for less than a second. ?? The click trains pass through the melon (the rounded region of a dolphin's forehead), which is made up mostly of fatty tissue. The melon acts as an acoustical lens to focus these sound waves into a beam, which is projected forward into water in front of the animal. Sound waves travel through water at a speed of about one mile per second--4.5 times faster than sound traveling through air. These sound waves bounce off objects in the water and return to the dolphin in the form of an echo. ?? Because of their longer wavelength and greater energy, low frequency sounds travel farther than high-frequency sounds. Echolocation is most effective at about 5 to 200 meters for objects about 2 to 6 inches in length. The returning sound is received in the fatty portions of the lower jaw where they are then sent to the ear and onto the brain. Through this echolocation dolphins are able to determine the size, shape, direction and speed of objects in the water. Many details of this ability in dolphins have yet to be understood fully by science.
Bottlenose dolphins identify themselves with a signature whistle. However, scientists have found no evidence of a dolphin language. Sounds are probably produced by movements of air in the trachea and nasal sacs. During some vocalizations, bottlenose dolphins actually release air from the blowhole, but scientists believe that these bubble trails and clouds are a visual display and not necessary for producing sound. Bottlenose dolphins produce clicks and sounds that resemble moans, trills, grunts, squeaks, and creaking doors. They also produce whistles. They make these sounds at any time and at considerable depths. The sounds vary in volume, wavelength, frequency, and pattern. A mother dolphin may whistle to her calf almost continuously for several days after giving birth. This acoustic imprinting helps the calf learn to identify its mother.
The dolphin's senses are highly developed with acute hearing, eyesight and sense of touch. Like all toothed whales, dolphins have a limited sense of smell. Little is known about a dolphin's sense of taste although they do have taste buds and show strong preferences for certain types of food fish.
Going for a Swim
Bottlenose dolphins can often be found "surfing" off the bow of a boat to "hitch a ride" on the currents pushed forward by the boat, and this activity is considered good luck by boaters around the world. The bottlenose routinely swims at speeds of about 3 to 7 miles per hour and can burst to speeds of 18 to 22 miles per hour for short periods. ?? Although bottlenose dolphins generally do not need to dive very deep to catch their food, they regularly dive to depths of up to 150 feet. Under experimental conditions a trained dive was made to over 1,700 feet. They can dive for up to 8 to ten minutes and maintain a slower heartbeat while diving to slow the metabolism of oxygen. ?? Dolphins are quite acrobatic and can be seen doing complex and artful aerial maneuvers that awe spectators both in marine parks and in the wild. They are able to execute spins and flips that place them well out of the water during mating, demonstrations of hierarchical dominance or even just whimsical play.
Dolphins live in groups referred to as pods. Pods are coherent, long-term social units that vary in size and structure although composition is largely based on age, sex and reproductive condition. Many pods are composed of mother-calf pairs and pods of mature females and their recent offspring while others are made up of mixed-sex and single sex groups. Adult males have been observed alone, in pairs or occasional trios, moving between female groups in their age range, and pairing up with females for brief periods. Adult males rarely associate with sub-adult males. At times several pods may join for short periods to form herds or aggregations of up to several hundred animals. This is seen often and throughout the year in our bay. Whatever the size of the group, social hierarchy may often be observed in bottlenose dolphins.
A Long, Full Life
Census data from various conservation organizations and scientific study of dental material suggests that the average lifespan of a Bottlenose dolphin is about 20 years or less. While currently not endangered, it is important for us all to help conserve this beautiful creature. Their predators are various types of sharks, killer whales and disease such as bacteria and parasites. Pollution is also a factor in many areas, having caused the deaths of large numbers of dolphins in coastal areas. Many conservation organizations are making efforts to prevent this type of ecological disaster.
Come and See Them
Most people do not have the opportunity to observe bottlenose dolphins in the wild. The unique opportunity to watch and learn directly from live animals increases public awareness and appreciation of wildlife that exists only in dolphin centers such as the Vallarta Adventure Dolphin Center in Nuevo Vallarta Mexico. In the protected environment of our dolphin and marine mammal educational facilities our team of marine mammal experts can examine aspects of dolphin biology that are difficult or impossible to study in the wild, and people can observe, up close, these awesome and wonderful creatures. They are complex and amazing in ways that endear us to their species and astound our senses. Try one of our Dolphin Programs Today!