The common bottlenose dolphin (Tursiops Truncatus) is probably one of the most celebrated species of dolphin. Over the centuries, they have been a subject to both Greek and Roman mythology as a life saver to lost ships and sailors at sea. Today, they have become well known in TV shows such as Flipper and their common presences in a number of marine zoological parks around the world. Only recently has the common bottlenose dolphin has been classified as a separate species from the Indo-Pacific bottlenose dolphin of the southern hemisphere.
Gracie, a Pacific bottlenose dolphin in her forties at SeaWorld San Diego
Common Bottlenose dolphin
Measurements at Birth: Length: 33-55" (84-140 CM) Weight: 31-44 pounds (14-20 KG)
Maximum Measurements: Males: 8'-12' 6" (2.45-3.8 M) Females: 7' 10"-12' (2.4-3.7 M)
Weight: Males: Up to 1,100 pounds (500 KG) Females: Up to 570 pounds (260 Kg)
Lifespan: The average is mainly around 25-35 years but some captive animals have been known to live between 40-50 years.
The Range of the common bottlenose dolphin.
Bottlenose dolphins can be found in tropical and temperate oceans worldwide. Because they occupy a wide variety of habitats, bottlenose dolphins are considered to be one of the most adaptable cetacean. There are even coastal populations along the continents and around most oceanic islands and atolls. However, these animals are more common in bays, estuaries, and the lower reaches of rivers. In addition, there are pelagic offshore populations centered far offshore such as in the Gulf Stream of the North Atlantic and the Eastern Tropical Pacific. Overall, bottlenose dolphins are mainly found where water surface temperatures are in the range of 45 to 90 degrees F. While Atlantic populations may have a seasonal migration between New Jersey and North Carolina, California populations often migrate into the Baja during the winter months.
While it is not known if bottlenose dolphins have a formal language of their own. However, they do communicate with signature whistles to identify both themselves and other dolphins. Because dolphins lack vocal cords, they use their sphincter muscles within their blow holes to produce a complicated system of whistles, clicks, squeaks, moans, and trills. Bottlenose dolphins, like all other toothed whale species, are known to use echolocation (sonar) to send out frequencies by clicking. These clicking sounds then bounce off objects before returning sound waves that are picked up by the dolphin's forehead and lower jaw and interpreted as to distance, size, and shape of object. This unique sound system is useful at night and to navigate in murky waters even if the dolphin's visibility is poor. Overall, bottlenose dolphins have been known to produce sound frequencies from 0.25 to 200 Khk, using the higher frequencies for echolocation, and the lower frequencies for communications and orientation.
While female bottlenose dolphins sexually mature at around 5-8 years of age, it may be another 7-10 years before they have their first calf. Males usually sexually mature at around 8-12 years of age. During breeding, a single female may breed with multiple male partners in very short sequences in one season. This can make determining the sires of calves very difficult by researchers who study dolphins in both a wild and captive environment. The gestation period for the bottlenose dolphin is around 11-12 months. Although calves can be born anytime of the year, births during the winter months is very rare. While dolphin calves are weaned at around 18-20 months old, they may remain associated with their mothers for several more years. A female bottlenose dolphin may produce a single calf every three years. About 35% of all dolphin calves die during their first year.
Common bottlenose dolphins prey on a large variety of organisms, depending on the habitat. Animals who live in coastal regions tend to feed on fish and invertebrates that live on or near the bottom. Offshore dolphins tend feed on pelagic fish and squid. Bottlenose dolphins may forage individually and cooperatively. They are well known for catching their prey by fish whacking, or the method of striking a fish with the flukes and knocking it clear of the water. They have also been observed driving schools of fish onto mudflats and partially beaching themselves to collect the fish.