Written and photographed by Ron Toft

Every year, all over the world, millions of people flock to sea life parks and aquaria to marvel at the antics of Atlantic bottlenose dolphins. Both children and adults watch enthralled as these charismatic creatures play with and talk to one another, power their streamlined bodies through the water with ease and perform stunning, synchronised acrobatics.

Florida's Dolphin Research Centre

Bottlenose dolphins have always held a special place in people's hearts, and one of the best places to see these beautiful mammals at close quarters is the Dolphin Research Centre (DRC) (www.dolphins.org) on Grassy Key, Marathon, in the Florida Keys. This is where the original Flippers of TV and movie fame were trained.

The DRC has undergone many changes since its establishment, in 1958, by Milton Santini as Santini's Porpoise School. One of Santini's smartest dolphins, Mitzi, was the star of the pilot Flipper movie. After Santini sold the facility, in 1972, to an entertainment conglomerate, it became known as Flipper's Sea School - a roadside dolphin show. The centre was later acquired, in 1977, by whale conservationist Jean Paul Fortom-Gouin, who renamed it the Institute for Delphinid Research and closed the facilities to the public. During his ownership, Fortom-Gouin discovered that dolphins could understand simple vocabulary and syntax.

When a moratorium on whaling was introduced, in 1983, by the International Whaling Commission, Fortom-Gouin gave the business, the dolphins and debts, to his general manager and head trainer, Jayne and Mandy Rodriguez, and leased them the property for five years. The following year, the centre reopened once again as the non-profit Dolphin Research Centre.

Pioneering research

Today, the DRC is not only a magnet for tourists, annually attracting 50,000-60,000, but a pioneering research and educational facility whose staff fervently believe that the more we learn about dolphins, the more determined we will be to take care of all marine wildlife. There are currently 16 dolphins at the DRC. One of them, Theresa, arrived 38 years ago, in 1968, and is the centre's oldest dolphin. She has also been there longer than any other dolphin or person.

Research at the DRC takes various forms. Cognition, behaviour, ecology and physiology are all the subject of projects aimed at shedding new light on the lives and abilities of bottlenose dolphins.

Can dolphins count?

In August 2005, a ground-breaking paper, written by senior research scientist Dr Kelly Jaakkola, demonstrated conclusively what DRC researchers had known for years - that dolphins can grasp numerical concepts. It was published in the peer-reviewed Journal of Comparative Psychology. "Human infants know that one rock is different from two rocks, but it's unclear if they know that one rock is less than two rocks," said Dr Jaakkola. "The ability to distinguish and choose the set with fewer objects probably develops early in children's second year of life. Scientists call this relative numerousness. For our study, we wanted to see if dolphins also have the capacity to choose 'numerically less'."

In test sessions at the DRC, male dolphins were shown a series of black boards with white dots to see if they could choose the boards with fewest dots. They could. In fact, two dolphins, Talon and Rainbow, chose correctly more than eighty per cent of the time when shown all possible pairs of numbers between one and eight. Female dolphins were not involved in the study.

Although similar studies have been conducted with primates, this is the first time that dolphins have been clearly shown to understand advanced numerical concepts. The 'numerically less' study, says the DRC, greatly expands mankind's knowledge of dolphins' cognitive abilities and may show how they respond to numerical situations in the wild. "The more we understand about what kinds of numerical tasks different animals, including humans, can do, the better we will be able to understand the evolution and development of numerical cognition in both humans and other animals," remarked Dr Jaakkola.

Publication of the 'numerically less' paper was viewed by everyone at the DRC as a momentous achievement and the realisation of a long-term goal. "We've been trying to strengthen and build our research department and get our dolphins involved in more projects. For years, we've worked hard to become an outstanding research facility. Now we are seeing those efforts come to fruition."

Good parenting

Another research topic involves monitoring the social development of each calf to see how much time it spends with its mother, with its fellow dolphins and on its own. Scientists also want to find out if experience as a 'babysitter' makes an adult dolphin a good parent. Other research projects include profiling blood from DRC and other captive and wild dolphins to learn more about their immune system, and studying the so-called 'signature whistle' believed to be unique to each dolphin.

The Cetacean family

Befriended by humans for thousands of years, Atlantic bottlenose dolphins (Tursiops truncatus) are superbly adapted for life on and under the ocean waves. They are found both inshore and offshore in tropical and temperate waters globally and are the largest of the 'beaked' dolphins - those with elongated rostrums or snouts.

Dolphins, porpoises and whales belong to the scientific order Cetacea and so are closely related. There are more than 30 dolphin species. Dolphins have been around a long time; their fossils date back 11 million years.

Many people confuse dolphins with porpoises. Dolphins have a protruding snout, cone-shaped teeth and a large, sickle-shaped dorsal fin, whereas porpoises have a blunt, rounded snout, flat, spade-shaped teeth and a small, triangular dorsal fin. Generally speaking, porpoises are smaller than dolphins. Largest of all the dolphin family is the mighty Orca or killer whale.

Dining out

The food eaten by wild bottlenose dolphins varies according to where they live. Large, open water pods tend to dine mainly on blue whiting, cod and squid. Dolphins frequenting the southeastern waters of the USA have a much more varied diet. Among their 50-plus prey items are mullet, herring, smelt, capelin, catfish, eel and shrimp.

Dolphins swallow their food whole without chewing it, using muscles at the back of their tongue to squeeze the water out and the food down. The oesophagus (gullet) and trachea (windpipe) in dolphins and other cetaceans are completely separate, allowing them to swallow fish under water without any liquid entering their lungs.

The larger family unit

Dolphins do not have a mating season. Instead, they procreate all year round. Males become sexually mature when they are 10 to 13 years old, females when they are 8 to 12 years of age. A dolphin pregnancy lasts 12 months. Newly born calves tip the scales at between 10 and 16 kilogrammes and are usually about a metre long.

Mothers and calves live in maternity pods or nursery groups and stay together for three to six years. Females not only assist with the birth of other calves but also help to rear young dolphins.

A study of beached dolphins in Florida indicated that 38 per cent died before the age of 2 and 64 per cent within their first 10 years. Although it is possible for bottlenose dolphins to live to be over 50, this is rare in the wild.

Above and below water

Dolphins can descend to great depths, the record for a bottlenose being over 300 metres. When diving, a dolphin's heart can beat as slowly as 12 times a  minute to conserve energy and oxygen. Back at the surface, the rate can soar to 120 beats per minute. Dolphins can see well above and below water, but it is not known if they can see in colour like humans.

Communication and interaction

Among the distinctive noises made by these mammals are whistles, squeaks and clicks. Clicks, which are focused into a narrow beam by a waxy, lens-like structure within a dolphin's forehead, are used to detect objects sonically. This renowned echolocation system can pinpoint objects up to almost 100 metres away.

DRC visitors can interact with bottlenose dolphins in various ways, from simply shaking flippers at the water's edge and swimming with them in a structured way for 20 minutes to becoming a trainer or researcher for a day. People who want to help beyond paying the admission price or interaction fee can do so in various ways, such as joining the centre's Dolphin Society, making a donation and adopting a dolphin.

High intelligence

Bottlenose dolphins are remarkable creatures. Having viewed, touched and photographed them on many occasions over the years, I find it hard to escape the conclusion that there is intelligence of a very high order behind those smiling eyes. Intelligence of a wholly different kind to ours, perhaps, but intelligence nevertheless. Who knows, perhaps dolphins study people as much as we study them. One thing is certain: the marine world would be very much poorer without them