Pacific Bottlenose Dolphin (Tursiops gilli)
Suborder: Odonticeti Family: Delphinidae
Common in Hawaiian waters.
Other known names:
Grey porpoise, Black porpoise, Cowfish
Identity Keys to use in the field:
Robust body, Round melon, Single blowhole, Pointed flippers, Dark cape (area of the back around the dorsal fin), Lighter under-side, Fast active swimmer, Often bow-rides
General description and habits:
Bottlenose dolphins vary greatly in size. It's possible for two to be a different size, shape and color from one another, even if they live in the same school. If they come from different populations, they will be even more different. Some of the world's largest bottlenose dolphins live around the United Kingdom. They can be a good meter longer than those living off Florida and will be fatter with shorter beaks. There seem to be two main types of bottlenose. Inshore dolphins living nearer the coast are smaller and thinner, and offshore dolphins that are larger and fatter. Their size will also depend on the temperature of the water they live in - the colder it is, the more blubber they need. The easiest way of recognizing a bottlenose is to look for an obvious dark and curved-back dorsal fin. They can be confused with other dolphins such as spotted and humpback dolphins. The shape of their dorsal fin, along with nicks, scratches and other markings on their skin, are what researchers use to identify individual bottlenose dolphins. They have between 40 and 52 teeth in their upper jaw and 36 - 48 teeth in their lower jaw. Bottlenose dolphins from different parts of the world are very different sizes. There can be as much as a two meter size difference between adults. They can range from 1.9 to 4 meters in length (6.25 - 13 ft). Newborns can also vary quite a lot in length. They can be anywhere between 85cm and 1.3 meters (34in - 4.25 ft). Bottlenoses can also be very different weights especially depending on where they live. Some of them are more than four times as heavy as others. Adults can weigh between 150 and 650 kg (330 - 1435 lb) and newborns between 15 and 30 kg (35 - 65 lb). Bottlenose dolphins are very active and are often be seen bow riding, surfing, lob tailing and breaching. They can leap several meters out of the water. They can sometimes be seen playing with things such as seaweed, coral or other animals. Bottlenoses, like many other whales and dolphins, are social animals. Although they can be found on their own, they tend to live in family groups called schools. These can contain anywhere from just two or three dolphins to 500. Within these schools, they tend to spend time with similar individuals. Females and young calves are often found together, older calves spend time with each other and males form their own groups. The way in which bottlenose dolphins feed and catch their food can varies depending on where they live. They change their behavior and work out ways of catching food that suit the situation. In South Carolina dolphins chase fish onto the shore and then roll up on the beach to catch them. In the Gulf of Mexico, dolphins are seen stunning fish by flicking them with their tail flukes and then picking them up from the surface.
Fish, krill, other crustaceans, and squid
Bottlenose dolphins are found in many places around the world but not in polar regions. In fact, they can be found off all the continents, and in-between, except around Antarctica. It is rare to see them any further north than the United Kingdom or any further south than New Zealand. Many of the inshore bottlenose dolphins are resident all year round. This means they can always be found in and around the same place and don't migrate to other areas.
The worldwide population size of bottlenose dolphins is not known.
Hunting/Whaling, Habitat loss, Human disturbance, Chemical pollution, Entanglement in fishing nets, Captive cetacean industry
When a calf is first born, its mother will whistle over and over again so the calf will learn her whistle and always be able to find her, even among other mothers and calves. Bottlenose dolphins have been known to bow-ride in front of large whales such as humpbacks, pushed along by the larger animals pressure wave. Female bottlenose dolphins generally live longer than males and can live to over 50 years of age. It is unlikely that they would live that long in captivity. Bottlenose dolphin milk contains 14% fat. That is over 3 times the amount of fat in human milk. Some researchers have suggested that bottlenose dolphins can stun their prey by producing very loud or focused noises. In the town of Laguna in Brazil fishermen catch fish with the help of local bottlenose dolphins. The men stand on the beach with their fishing nets and the dolphins drive the fish towards the beach. As they get near to the men, the dolphins roll over on the surface of the water, and the men use this as the signal to throw their nets. Any fish escaping the nets swim straight into the group of the waiting dolphins.