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Order Description

Cetacea


Order Description

Cetaceans (whales, dolphins and porpoises) are the most diverse and familiar marine mammals in the western North Atlantic. They are exclusively aquatic, and mostly found in the marine environment. Many are large to very large animals. The Blue Whale Balaenoptera musculus is the largest living mammal, reaching a length of 31 meters (102 ft) and weighing 177,811 kg (392,000 lbs).

cetaceans have many unique characteristics that allow them to live in the water, including breathing adaptations, swimming adaptations, and the use of echolocation. Their bodies are elongate or streamlined. They have short necks, long tails, and forelimbs that are flipper - shaped. The end of a Cetacean's tail is flattened and fluke - shaped. Most species also have a dorsal fin located along the mid-line of the back. Their nostrils are located on the top of their head, and are visible as the blowhole. All species lack external hind limbs. They have no external ear coverings. Their eyes are small, and they are almost hairless. They have a very thick subcutaneous layer of fatty tissue called blubber, which substitutes for hair as an insulating layer.

This order is divided into two groups (suborders) based on feeding habits:

-Odontoceti - "toothed whales" which are predators of fish and other aquatic animals.

-Mysticeti - "baleen whales" which filter-feed on plankton.

The three families of baleen whales are represented by 10 species worldwide. There are at least seven families of toothed cetaceans, represented by approximately 66 species worldwide. Eight species of baleen whales and 31 species of toothed whales have been reported from the western North Atlantic Ocean. Only a few of these species frequent the Georgia coast.

Family Balaenidae

This family includes three species of Right Whales. These are medium to large whales, ranging from 5.5 to 17 m (18-56 ft) long. These whales feed by skimming the surface of the ocean for plankton. They are found in all temperate oceans, and visit coastal areas.
Species in this family:
    Right Whale (Eubalaena glacialis)

Family Balaenopteridae

This family contains six species commonly referred to as Rorquals. They are medium to large whales ranging from 8 to 27 m (26-89 ft) long. They feed by gulping swarms of planktonic crustaceans or small fish. This family includes the well known Humpback Whale (Megaptera novaeangliae).
Species in this family:
    Bryde's Whale (Balaenoptera brydei)

Family Delphinidae

This family includes dolphins and small whales. These are small to medium cetaceans between 1.5 and 9.5 m (5-31 ft) long. This is the largest family of toothed cetaceans, containing 34 species worldwide. Its members inhabit open oceans, estuaries, and coastal areas. Small species feed on fish, squid, or crustaceans. Larger species prey on pelagic fish, seals, and other cetaceans. Several species are hunted commercially. This family includes the species most commonly seen along the Georgia coast, including the Bottle-nosed Dolphin (Tursiops truncatus).
Species in this family:
    Atlantic Spotted Dolphin (Stenella frontalis )
    Bottlenose Dolphin (Tursiops truncatus)
    False Killer Whale (Pseudorca crassidens )
    Pygmy Killer Whale (Feresa attenuata)
    Rough-toothed Dolphin (Steno bredanensis )
    Short-finned Pilot Whale (Globicephala macrorhynchus)
    Striped Dolphin (Stenella coeruleoalba)

Family Kogiidae

This family includes the small sperm whales. The average adults range from 2.1 to 3.4 m (7-11 ft) long and weight up to 408 kg. They have a body shape similar to that of the Sperm Whale (Physeter macrocephalus). This family has two species. Both feed mainly on squid, fish, and crustaceans.
Species in this family:
    Dwarf Sperm Whale (Kogia simus )
    Pygmy Sperm Whale (Kogia breviceps)

Family Ziphiidae

This family includes the beaked whales. These are medium whales, ranging from 4 to 12.4 m (13-41 ft) long. Beaked whales are open ocean species and therefore are seldom seen. They are deep divers that feed on squid and fish.
Species in this family:
    Dense-beaked Whale (Mesoplodon densirostris )
    Gervais' Beaked Whale (Mesoplodon europaeus )
    Goose-beaked Whale (Ziphius cavirostris )