There are about 40 species of dolphins known to exist in Earth's oceans and fresh water rivers. Some, like the bottlenose dolphin, are much more known to the public and to scientists. Research on dolphin intelligence, for instance, has been done predominantly with bottlenose dolphins in captivity. Others, like the rough-toothed dolphins that stranded in Florida and are featured in our film, are less understood. Scientists are still trying to discover, for example, where these animals can be found!
Similar to the herds of animals that have roamed the plains of Africa and North America, dolphins travel the ocean in communities of varying size; and they maintain societies for mating, feeding, detecting predators and nurturing their young. Some dolphins live in deep water, and are more likely to travel in large communities numbering in the hundreds or even thousands. Others live nearer to shore, traveling in bands of maybe dozens or hundreds. Generally, we know more about dolphins that live out their lives nearer our coastlines, than those that roam the wide ocean, far from our view.
All dolphins belong to the scientific order cetacea, which comprises both whales and dolphins. Dolphins are further subdivided into various families, the largest of which is called Delphinidae. There are 32 dolphins in this family, including the bottlenose, Atlantic spotted dolphins, dusky dolphins, spinners, even orcas (also known as killer whales), the largest of all dolphins. Porpoises and river dolphins belong to different families. Porpoises are usually smaller than dolphins, have different shaped teeth, no beak, and their dorsal fins are shaped differently (and sometimes porpoises have no dorsal fin).
Scientists tell us that the ancestors of dolphins, whales and porpoises were land mammals called ungulates, or hoofed animals. Fifty million years or so ago these animals adapted to the rising ocean, eventually becoming mammals of the sea.
The first recorded encounters between people and Atlantic spotted dolphins along the Little Bahamas Bank was in the late 1960's when divers were salvaging the wreck of a Spanish galleon. Divers were frequently visited by friendly spotted dolphins that would approach, investigate, and often mimic divers' actions. In the mid-1980's, scientists began studying their distribution, associations with one another, behavior, even identifying individuals by gender and the pattern of their spots. Beginning at about four years old, young dolphins in this species begin developing black spots on their light underside and white spots on their dark topside. The older the dolphin, the more spots.
Dr. Kathleen Dudzinski, featured in our film, uses the spots and markings, such as scars from encounters with sharks or other dolphins, to help her identify each dolphin. In order to understand the communicative lives of these animals she must first understand who is "talking." Is it an older female reacting to a young dolphin? Is it two teen-aged dolphins interacting with one another? The more she knows about the animals, over time, the better she can search for clues and correlation's between certain sounds dolphins make and their behaviors.
Atlantic spotted dolphins live in the shallow, tropical waters off the Atlantic Coast of the United States, the Gulf of Mexico, and the Bahamas. It is when they're near-shore that Kathleen studies them. During the afternoon, they swim out to deeper waters in search of fish and squid. Atlantic spotted dolphins are relatively small compared to other dolphins. They are about six feet long and weigh approximately 200 pounds when they reach adulthood. The females of this species are generally larger than the males.
(Scientific Name: Lagenorhynchus cruciger)
Dr. Bernd Würsig, featured in our film, knows more about dusky dolphins than anyone in the world. He's been studying these acrobatic marvels since the 1970's. His dusky dolphin research takes him from Argentina to New Zealand, as duskies live in the temperate waters of the southern hemisphere.
Duskies are smaller than many dolphins, reaching a length of five to six or so feet. They have very short beaks and distinctive black and white coloring, but the most noted characteristic of the duskies is their highly acrobatic leaps. In addition to helping propel them more quickly through the water, duskies may be leaping for their dinner. By leaping high, they may be locating their prey by spotting flocks of birds feeding on schooling fish, sometimes miles away. These leaps also might communicate to other dolphins that dinner is near.
In Patagonia, off the shores of Argentina, Drs. Würsig, Alejandro Acevedo, and Dudzinski study the dusky dolphins that come in to the local bays in the spring, summer and fall to eat anchovies. The dolphins begin their search for food in groups of 20 or more. Würsig thinks that duskies watch for birds circling above the water and feeding on fish as a signal that anchovies are near. The several groups then race toward the school of anchovies and begin cooperatively herding the fish into a swirling school. The dolphins drive the fish toward the ocean's surface, using it as a barrier or wall that the anchovies cannot escape. At this point, there may be hundreds of dolphins working together to herd and consume the anchovies. The duskies call to one another in loud, excited squawks and whistles, leaping and slapping the water with their tails as they take turns herding and feeding.
Scientists want to know: who feeds first and how is that determined? Is it based on kinship ties or dominance? What signals do they give one another during this frenzied activity? The more we learn about dolphins, the more questions we are inspired to ask. And as long as there are dolphins, there will be ample opportunity for future scientists to make important contributions.
(Scientific Name: Tursiops truncatus)
The 1960's television show "Flipper," as well as oceanariums that care for captive dolphins, have made the bottlenose the most recognized dolphin species in the world. In fact, bottlenose dolphins inhabit temperate and tropical waters of almost every ocean, including the Mediterranean Sea and the Gulf of Mexico. Their popularity and anatomical "smile" cause many people to think dolphins are merry, friendly creatures eager to interact with humans. In some respects this is true. Dolphins are highly social animals, and in captivity, they tend to be eager to interact with humans and are more easily trained than other animals. Even in the wild, there have been many documented accounts of dolphins seeking human companionship, but generally speaking, they far prefer the company of their own kind. Why some dolphins separate from their group and interact with people is still a mystery.
In Dolphins, we meet Dean Bernal, a marine naturalist in the Turks & Caicos, West Indies, who has befriended a wild, bottlenose dolphin named JoJo. (see The JoJo Dolphin Project). Bottlenose dolphins are much bigger than spotteds and duskies. At about ten feet long and 600 pounds, JoJo is a powerful force! In fact, dolphins can be quite aggressive with one another and with other species, including humans. Several people have been injured and one person killed by a dolphin, but the blame often falls on the humans who don't understand how their actions can be interpreted as aggressive by the dolphin. It's interesting to know that the "killer whale," the largest of all dolphins, has never been known to kill a person. They are the top predator in the oceans, but have not harmed people.
Dean leads a public education program that stresses the importance of appropriate behavior around dolphins. While swimming with dolphins is illegal in U.S. waters, "swim with dolphin" programs are abundant and becoming more popular in other locations. Scientist Kathleen Dudzinski spent this last year in Japan studying bottlenose dolphins in an area that's becoming more popular with tourists as a "swim with dolphins" destination. Kathleen, Dean, and others concerned for the well-being of dolphins, tell us we need to understand dolphin communication, behaviors and life cycles, as well as their feeding and rest patterns, so that we don't disrupt their lives, or cause injury to dolphins or ourselves. Kathleen, Dean, and other scientists want us all to realize that, when we're in the ocean, we're in the dolphins' home.
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