The scientific order Cetacea is comprised of whales, dolphins, and porpoises. These aquatic creatures are the most specialized of all mammals, with adaptations that allow them to spend their entire lives in water. Living cetaceans are divided into two distinct suborders, Mysticeti and Odontoceti, which are divided further into a total of fourteen families. The Mysticeti suborder contains those whales which have baleen plates instead of teeth. A baleen whale feeds by straining water through the baleen, trapping the fish, shrimp, crustaceans, or krill inside its mouth. This suborder is comprised of the largest whale species, including the blue whale, the humpback whale, and the grey whale. Those cetaceans classified in the suborder Odontoceti are toothed whales, dolphins, and porpoises. They are generally smaller, faster, and more agile than their baleen counterparts. Scientists have identified approximately 80 species of toothed whales, ranging in size from the 60-foot sperm whale to the five-foot harbor porpoise. The various species are incredibly diverse and display a multitude of body shapes, behavior patterns, and lifestyles. Some spend barely any time on the surface, rising occasionally to take a breath; others can leap 20 feet out of the water almost effortlessly. Some species live in the shallows close to shore, some reside in deep oceans, and still others are found only in fresh water rivers. Odontoceti may have anywhere from eight to 250 teeth, and their eyesight ranges from poor to excellent. Delphinidae is the largest family within the Odontoceti suborder. Scientists have discovered fossil records of ancient delphinids, which date back 11 million years. This family is composed of what we commonly call dolphins. There are over 30 different species in this family, the largest of which is the Orca, or killer whale. Delphinids are characterized by sharp, cone-shaped teeth; most possess a falcate dorsal fin and a melon joined to a distinct beak.
Bottlenose dolphins are the largest of the beaked dolphins. There is a definite crease where the rostrum (snout or beak) joins the melon, and the shape of the mouth seems to form a permanent smile. Their bodies are dark gray on the back and sides, fading to a pinkish white belly underneath. Their dorsal fins are falcate, curving slightly to the back. Pectoral fins and flukes are pointed at the tips. Atlantic common bottlenose dolphins are usually 6 to 9 feet long at maturity(Reynolds 2000); the Pacific variety often may be larger. The largest member of the entire family Delphinidae is the Orca, better known as the killer whale.
A long, slender body and beak characterize this species (generally considered to have at least two forms, distinguished by range). The spotted dolphin's back is dark gray, contrasting with its light gray underbelly and sides. Dark gray patches may also occur around the eyes and on the beak. The amount of spotting varies with age as well as geographical location. Calves are born without spots; the spots begin to develop first on the stomach, then on the back, growing in size and number as the animal matures. Spotted dolphins are a relatively small species, growing to a maximum length of approximately 2.5 meters.
The common dolphin has been perhaps the most celebrated dolphin, depicted often in art throughout history since the time of the ancient Greeks. They have small, streamlined bodies, averaging about 2.5 meters, and long, slender beaks. Their coloring is most distinctive: the back is black to the middle of the tail stock; the flanks display an hourglass pattern of yellowish ochre and light gray, blending to grayish white along the sides of the tail. The rostrum is dark brown to black, and a narrow, dark stripe runs from the rostrum to the area surrounding the eyes.