|Florida Marine Mammals: Dolphins|
Several dolphin species occur in Florida costal waters. Dolphins
cooperate in many ways, some species more than others. As a group they
may guard against predation by sharks or support a sick or injured
community member in the water by keeping it afloat. A few dolphins
sometimes use the lengths of their bodies to encircle and pen a school
of fish in shallow water, like horses rounding up yearlings, in order to
feed. It is against federal law to feed or harass wild dolphins.
Swimming with or feeding dolphins can be dangerous for both human and
dolphin and should not be attempted.
Dolphins are often heard clicking. Contrary to popular thought, clicking is likely not communication, but rather the sonar system dolphins use for navigation, food-finding and avoidance of predators. Clicks are one of three classes of sounds dolphins produce, in addition to squawks (whose purpose is unknown, although these sounds are made while dolphins are socializing), and pure tones, one of which is known as that dolphin's "signature whistle."
Atlantic Spotted Dolphin-Atlantic spotted dolphins are found in the tropical and subtropical waters of the Atlantic Ocean, including the Florida coastline. They can also be found in the Indian Ocean and in some parts of the Pacific. The upper body of the Atlantic spotted dolphin is a dark gray color. This fades to a medium gray on the sides and a light ventral surface. They have a chunky beak with a spot of white on the end. The name of the Atlantic spotted dolphin comes from the spots that develop as the dolphin ages. The older the dolphin, the more spots. Adult females tend to be larger than adult males. The length of the Atlantic Spotted Dolphin averages about 7 feet and it weighs an average of 220 pounds. The typical family group of the Atlantic spotted dolphin can consist of 50 individuals but is usually somewhere between 5 and 15. They are very vocal and active at the surface. Atlantic spotted dolphins will often group with other types of dolphins. It has also been observed that pod of Atlantic spotted dolphins can be formed along lines of gender, age and reproductive status.
Bottlenose Dolphin- The most common dolphin in Florida waters is the bottle-nosed dolphin. Bottlenose dolphins have robust, powerful bodies that are blue-gray on top with lighter sides and bellies. This dolphin has an unusually short and stubby beak, hence the name "bottlenose". The bottlenose dolphin has more flexibility in its neck than other oceanic dolphins. As adults they are typically six to twelve feet long, and live both inshore and offshore along temperate and tropical coasts worldwide. Dolphins breathe air at the surface of the water through a single blowhole located near the top of the head. They need to breathe about every two minutes, but can hold their breath for several minutes. Their blow is a single, explosive cloud. Feeding behaviors for the bottlenose dolphin are diverse, primarily involving individual prey capture, but sometimes involving coordinated efforts to catch food, feeding in association with human fishing, and chasing fish into mud banks. Bottlenose dolphins eat a wide variety of food, consuming more than 20 pounds of mullet, sheepshead, pinfish, flounder and marine invertebrates each day. Male bottlenose dolphins reach sexual maturity at about 10 years. Females reach sexual maturity at about 5-10 years. The gestation period is 12 months. Calving can take place year-round with peaks in some areas during spring and fall. Calves nurse for over a year (12-18 months), and stay with their mothers for 3-6 years learning how to catch fish and other important tasks.
Common Dolphin- Common dolphins are colorful, with a complex crisscross or hourglass color pattern on the side; the long-beaked common dolphin being more muted in color. When looking at the profile of the two common dolphin species, the short-beaked common dolphin has a more rounded melon that meets the beak at a sharp angle, as compared to the long-beaked common dolphin that has a flatter melon that meets the beak at a more gradual angle. Common dolphins can reach lengths of 7.5 - 8.5 feet and weigh as much as 297 pounds. The short-beaked common dolphin is relatively heavier, and has a larger dorsal fin and flippers than the long-beaked common dolphin. The common dolphin feeds on squid and small schooling fish. Common dolphins have been seen working together to herd fish into tight balls. Like many other dolphin species, the common dolphin will sometimes take advantage of human fishing activities, feeding on fish escaping from the nets or discarded by the fishermen. Common dolphins are found in the Atlantic from Newfoundland and Nova Scotia to northern South America. They frequent offshore waters around the outer continental shelf, often near ridges. Common dolphins are rarely sighted near shore.
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