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Bottlenose Dolphins

Kingdom:

Animalia

Phylum:

Chordata

Class:

Mammalia

Order:

Cetacea

[Suborder]:

Odontoceti

Family:

Delphinidae

Genus:

Tursiops

Species:

truncatus

What is taxonomy?

Bottlenose dolphins usually travel in groups of 10-25 individuals.  Herds of several hundred have been reported in offshore regions in temperate climes all over the world.  There appears to be two different forms of bottlenose dolphins, a coastal form and an offshore form.  Body shape varies although generally  bottlenose dolphins have a chunky head and trunk, a distinct snout and dorsal fin, pointed pectoral flippers, and they range in color from light to charcoal gray. 

Interesting Facts:

  • Bottlenose dolphins are the most studied cetacean in the wild because they live near coasts, and in captivity because they adapt well to oceanariums. 
  • Bottlenose dolphins often ride the bow waves of moving vessels, have been reported riding pressure waves of big whales, and body surfing in nearshore waves.
  • There are stories about wild dolphins aiding or interacting with humans.  A bottlenose dolphin that was named Percy resided off the coast of Cornwall, England.  He followed local fishing boats, played with their crab pots, and even allowed strangers to hang onto his dorsal fin as he pulled them through the water. 
  • In many areas, bottlenose dolphins have adapted feeding strategies to human activities, eating netted fish and fish discarded by fishermen.  Various kinds of cooperative hunting with fishermen have been reported.

What should I know about bottlenose dolphins?

Where do bottlenose dolphins live?

Bottlenose dolphins can be found throughout the world in harbors, bays, gulfs, and estuaries of temperate and tropical waters.  Bottlenose dolphins live in the Baltic Sea, Mediterranean and Black Seas, and the southwestern Indian Ocean.  In the Pacific Ocean, they range from northern Japan and southern California to Australia and Chile.  In the Atlantic Ocean, they range from Georges Bank, off Massachusetts, and the British Isles to Golfo San Matias, Argentina, and northern Namibia.

How many bottlenose dolphins are there?

The worldwide population of the bottlenose dolphin is unknown although populations in specific areas have been estimated.  Bottlenose dolphins are not considered endangered.  You can read more about bottlenose dolphin stocks in the NMFS Alaska and Atlantic stock assessment reports.

How can I identify a bottlenose dolphin?

Bottlenose dolphins are  8-12 feet (2.4-3.7 meters) long.  Their coloration varies from shades of gray (gray-green, gray-brown, light gray) on the backs to white below the jaw and on the belly.  Bottlenose dolphins have 18 to 26 small, sharp teeth on each side of their upper and lower jaws.  Bottlenose dolphins are one of the best known cetaceans, as they are displayed at oceanariums and are frequently seen on television and in movies. 

How well can a bottlenose dolphin  see or hear?

All dolphins, including the bottlenose dolphin,  have strong eye muscles that can change the shape of the eye lens in order to focus in both air and water.  Dolphins can recognize some colors and their pupils can adjust to light and dark changes in their environment.   Dolphins have a well-developed sense of hearing and navigate their environments through echolocation.   Dolphins have very sensitive skin, which is easily damaged but also heals quickly. 

What do bottlenose dolphins eat?

Coastal bottlenose dolphins eat a wide variety of fish, squid, and crustaceans while offshore bottlenose dolphins prefer squid.   Instead of using their teeth to chew their food, dolphins grip food with their teeth, then swallow it whole--head first--so the spines of the fish don't catch in their throats.   Bottlenose dolphins sometimes cooperate with each other when hunting and have been reported herding fish into groups then take turns charging through the schools to feed, or trapping schools of fish against sand bars for an easy dinner. 

How do bottlenose dolphins have their young?

Dolphins rely on behavioral signals to indicate their willingness to mate.   Their approximately 3-4 foot calves are born after a 12-month gestation period, and they nurse for more than a year after birth.   Sometimes another dolphin (male or female) stays close by the new mother and calf  to assist them. This assisting dolphin, called an "auntie" dolphin, is often the only other dolphin that a mother will allow near her calf.   Mature female dolphins generally give birth every 2-4 years. 

How long do bottlenose dolphins live? How do they die?

Bottlenose dolphin generally live between 30 and 50 years.  Bottlenose dolphins are sometimes preyed upon by killer whales or large sharks.  Bottlenose dolphins sometimes get caught in fishing nets and can also be affected by pollution and near shore habitat destruction.

Where can I find more information about  bottlenose dolphins?

Books and the world wide web are excellent places to learn more about marine mammals. 

Books

  • Leatherwood, Stephen. Reeves, Randall R. Foster, Larry.   The Sierra Handbook of Whales and Dolphins.  Sierra Club, San Francisco, CA.  1983.
  • Leatherwood, Stephen.  Reeves, Randall R. Perrin, William F.   Evans, William E.  Whales, Dolphins, and Porpoises of the Eastern North Pacific and Adjacent Arctic waters; A Guide to their Identification.  Dover Publications, Inc., New York, NY.  1988.
  • Wynne, Kate. Folkens, Pieter. Guide to Marine Mammals of Alaska.  Alaska Sea Grant Program.  University of Alaska Fairbanks, Fairbanks, AK.  1992. 

World Wide Web

There are many more sources to learn about cetaceans.   Check with NMML's online library or your local librarian for her or his recommendations

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