bottlenose dolphins

Bottlenose Dolphins – Basic Knowledge

The bottlenose dolphin is the most studied and best known of all cetaceans. This is primarily due to its ready adaptability to captive environment, such as research facilities and marine parks, and its appearance on the TV show Flipper. This dolphin has an extensive range and is the most encountered dolphin species in coastal U.S. waters.

PHYSICAL DESCRIPTION: The bottlenose dolphin has a long and robust body shape, with a pronounced, stubby beak (hence the name ‘bottlenose’), and a distinct melon. Because 5 of the seven neck vertebrae are not fused together as in other dolphin species, the neck of these dolphins is more flexible. They have about 40-48 sharp conical-shaped teeth in both the upper and lower jaw.

COLOR: The color of bottlenose dolphins may range from light to dark lead gray, with lighter shading on the sides, and a white, sometimes pink to pinkish-gray belly.

FINS AND FLUKES: The dorsal fin is triangular, curved and moderate in size, up to 35 cm in height, and located near the middle of the back. The flukes are proportional, curved, with a deep median notch, and are 65-80 cm from tip to tip. Their flippers are pointed and of moderate length.

LENGTH AND WEIGHT: Adult bottlenose dolphins can reach 4 meters (12 feet) in length, and, in some geographical areas, weigh as much as 650 kg (1,430 pounds). However, in most part of the world their weight seems to be limited to about 350 kg (770 pounds). Males are typically larger than females.

FEEDING: These dolphins can be found foraging in deep and very shallow waters. They may hunt and feed individually or in a concerted effort of a group, chasing fish against the water surface, onto mud banks, and shorelines. Association with human fisheries is also reported. They consume about 8-15kg (15-30 pounds) of food each day. Their diet includes a variety of fish species, but also squid and crustaceans.

MATING AND BREEDING: Male bottlenose dolphins reach sexual maturity at age 10, females between 5 and 10 years of age. The gestation period (pregnancy) is 12 months and calves are born in all seasons although in some geographical areas seasonal peaks during spring and fall have been reported. Females give birth once every 3-4 years. At birth, calves acre about 100 cm (3 feet) in length and may weigh around 10 kg (22 pounds). Calves depend on their mother’s milk for 12-18 months but stay with their mother for up to 5 years learning how to catch fish and the social skills to become a full member of dolphin society.

DISTRIBUTION AND MIGRATION: With the exception of polar waters, bottlenose dolphins are found in every ocean around the world, in coastal waters and the open sea. They are frequently encountered in estuaries, lagoons, bays and harbors. There appears to be a coastal and offshore ecotype. Population density appears to be higher in near-shore areas. Bottlenose dolphins are known to have limited home ranges or may be migratory.

NATURAL HISTORY: Like all mammals, dolphins are warm blooded, breathe air, give birth to live babies, feed their new born milk, and are born with hair. Being warm, blooded, or homeothermic, dolphins maintain a constant body temperature regardless of the surrounding water temperature. Unlike terrestrial mammals, including humans, dolphins are conscious breathers, meaning they must be aware of their breathing to avoid involuntarily taking a breath while underwater. Bottlenose dolphins can dive for as long as 20 minutes but typically hold their breath for only 30 seconds to 3 or 4 minutes between breaths.

Bottlenose dolphins may live for 50 years or more, with females generally living longer than males. They live in social communities, sometimes called pods. Group size in near-shore populations is typically 30 or less while offshore groups may comprise several hundred individuals.

Even though they appear to live in relatively open societies, they exhibit strong social bonds that help provide protection against predators, assist in locating and catching food, and aid in the rearing of their offspring. Like in other social animals, play is an important part of learning. Behaviors such as fish toss, bow riding and seaweed-keep-away are considered play but also help dolphins develop social bonds as well as useful hunting techniques. They use multiple feeding strategies, including “fish whacking,” where they strike a fish with their flukes and knock it out of the water, and driving schools of fish into shallow areas or onto mudflats. Bottlenose dolphins use high frequency echolocation to locate and capture prey, and high-pitched ‘whistles’ to communicate with one another.

THREATS: Bottlenose dolphins are protected in U.S. waters by the Marine Mammal Protection Act. While the species is not considered endangered, they are near depletion in some areas and threatened in many others. Incidental and direct exploitation are generally reported at moderate to low levels. According to NOAA, current threats come primarily from incidental injury and mortality from fishing gear (such as gill net, seine, trawl, and long-line commercial and recreational operations), exposure to pollutants and biotoxins, viral outbreaks and direct harvest in some countries (e.g. Japan and Taiwan). Studies of large, high mortality events over the last decades suggest that the immune system of these animals can be severely affected by heavy metals, PCBs and other pollutants.

In an effort to reduce injury and mortality of coastal bottlenose dolphins along the eastern seashore of the U.S., the National Marine Fisheries Service implemented the Bottlenose Dolphin Take Reduction Plan (BDTRP). This initiative includes provisions for research and education, and requires modifications of fishing practices for small, medium, and large-mesh gill-net fisheries from New York to Florida.


We all depend on a healthy ocean; a healthy ocean depends on us. Let us be the change we would like to see in the world.  Our new Ocean Sentinels Club is proof that conservation can be fun, rewarding and effective.  The Club unites and empowers citizens to advocate for the conservation of dolphins and the marine environment across Palm Beach County, and beyond. Join us. The time is now. It begins with you.

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The Face is Familiar, but …



The casual identification of individual cetaceans probably started when humans began interacting with coastal species over a century ago, when whalers and fishermen could identify a few individual killer whales by the shape and coloration of the dorsal fin. This technique, much refined, is still used today.

Scientists, studying cetaceans have long understood and appreciated the need to track individual whales or dolphins. Identifying individuals can help in the collection of information on group composition, site fidelity, movement patterns, population size, as well social structure. Given that dolphins and whales are extremely social animals, understanding the social structure of the population is vital to understanding cetaceans.

Most cetacean studies are conducted from the surface, where the dorsal fin is often the only visible part of the dolphin and therefore the only part usable as an identifier. Luckily, the trailing edge of the dorsal fin, which consists of a thin sheet of flesh and connective tissue, is the most identifying feature of most dolphins and porpoises. Small nicks or larger notches in this area of the dorsal fin are consistent markings that can be used to track individuals over time. However the shading, coloration and overall shape of the dorsal fin can also be helpful.

Some cetaceans have other areas that are more useful as identifiers. The humpback whale has unique markings on the bottom of its flukes, the right whale has large crusty growths on its upper lip that grow in unique patterns and are used to identify individuals and the spotted dolphins have spots; clusters and constellations of spots which are great individual markings and very helpful in the identification process. These dolphins, however, get more and more spots as they develop from infants to adults, identifying spot clusters get covered by new spots, and so it is important to continuously track them over time. All of these identifiers are, in most cases, very subtle, and hard to track in the field. This is where capturing images with photo or video cameras becomes important.

In nearly all studies of cetaceans that track individuals, photo-identification techniques are used to some degree. Most researchers depend on their cameras and photo files a great deal. To get a usable id photo from the surface, it is important to get the dorsal fin on film from a 90-degree angle. This eliminates distortion from angle and helps prevent misidentifications. Any time, we can observe dolphins from underwater, we can use the entire body of the dolphin for identification purposes, which can be very useful, especially in the case of spotted dolphins where we use the spotting pattern across the entire body to identify individual dolphins.

As any field researcher will tell you, it takes a great number of photos to get usable shots. But then, experience does matter and now that we use digital photography, having to throw away bad shots does not hurt as much as it did when we used film.


We all depend on a healthy ocean; a healthy ocean depends on us. Let us be the change we would like to see in the world.  Our new Ocean Sentinels Club is proof that conservation can be fun, rewarding and effective.  The Club unites and empowers citizens to advocate for the conservation of dolphins and the marine environment across Palm Beach County, and beyond. Join us. The time is now. It begins with you.

Read more

Florida’s Wild Dolphins Reveal Unique Social Feeding Behavior

For the last decade, the Taras Oceanographic Foundation, under a general authority of the National Marine Fisheries Service, has been conducting dolphin surveys in Palm Beach County. We position or boat within three miles from shore, and travel at slow speed, until we see dolphins. We will then follow the dolphins long enough to photograph each dolphin and document their behavior. And although we have studied wild dolphins for decades, we still find new and different behaviors that are remarkable.

There are days when bait fish seem to fall fro m the sky. On those special days, when the seas are flat, we watch all kin ds of fish jumping out of the water; some high in the air in a single arc, others low and repeatedly as they travel some distance. Flying fish routinely glide, with ease, for several meters. Ballyhoo and Bonita will jump to avoid being eaten. Every once in a while, a clever dolphin will take advantage of these jumping fish; a clever dolphin like Odyssey, and her offspring.
Odyssey was conducting a master class in the art of catching fish. And when I say ‘catching fish’ I mean CATCHING fish. She was throwing a fish into the air, and artfully catching with in her mouth. She demonstrated the process a few times for her calf, and then did something remarkable.

She bit off the head of the fish, before throwing the body in the air, for her calf to catch. We could not help but make the comparison of a mother cutting the crust off a sandwich, before serving it to her child. But it is more than that; she was keeping her calf safe.
For the significance of this simple act, we need to first ex­ amine the basic anatomy of a fish. Fish use gills to acquire oxygen from the water. These gills are located just at the base of the head. When a fish breathes, it draws in a mouthful of water and pulls the sides of its throat together, forcing the water through the gill openings, which expand away from the body.

Dolphins do not chew their food. It is imperative, therefore, for a dolphin to swallow their prey, head first. If a fish were eaten tail first, it might expand its gills while passing through the throat of the dolphin and become wedged. In all the necropsies I performed, I once found one dolphin with a fish caught in its throat. The fish was swallow ed tail first, and the res ult was deadly. Back to Odyssey and her calf.
She was biting the heads off the fish, so her calf would not catch the fish backwards and choke to death. She threw the fish body high in the air, and her calf made repeated attempts to make the catch. More likely motivated by the game than the food, the small dolphin was still nursing and probably not too hungry. Over the next few months, as this calf grows, Odyssey will insist it hunt down its own food. The catching strategies learned now, will be all the more important in the future.

But even the best strategies and the most prepared youngster will not grow to be an adult unless there continues to be the abundance and variety of fish to eat. We are currently living through the sixth mass extinction event this planet has experienced. ln the past, these epic occurrences were the result of volcanic eruptions or asteroids striking the earth, but this time they are our own doing.

Why is it important to study dolphins? Sure they are cute and all, but why should anyone support such endeavors? Because in many ways, we are alike. Dolphins eat the fish we eat. They raise their kids to be better citizens and work every day to make a living and support their families. They are the masters of the ocean environment; a subject about which we are remarkably naive. And the ocean is vital to the survival of us both.

Although we continue to harvest the resources the oceans provide, at unsustainable rates, we could learn from the marine mammals how to find areas of highest productivity and hunt selectively. As we increase the noise in the ocean with our recreational watercraft, commercial ships and military exercises, we learn from the dolphins that in the deep ocean, it is by listening and hearing we can have the best vision. Marine mammals are the ocean canaries, warning us about the disastrous effects of pollution and habitat destruction, and they can be our guides to find answers, to questions we have not yet thought to ask about the ocean realm.

It is through the long- term studies like the one we have been carrying out in Palm Beach waters, that dolphins teach us about the ocean, the world and ourselves. We just have to keep going to school.


We all depend on a healthy ocean; a healthy ocean depends on us. Let us be the change we would like to see in the world. Our new Ocean Sentinels Club is proof that conservation can be fun, rewarding and effective. The Club unites and empowers citizens to advocate for the conservation of dolphins and the marine environment across Palm Beach County, and beyond. Join us. The time is now. It begins with you.

Read more