View Full Version : Week 20 - Killer Whale

October 3rd, 2007, 02:25 PM

Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Suborder: Odontoceti
Family: Delphinidae
Genus Orcinus
Species orca

The orca or killer whale is a toothed whale that is an efficient predator, even attacking huge young blue whales. Their only enemy is human beings. Orcas live in small, close-knit, life-long pods and have 1 blowhole. The killer whale belongs to the family of dolphins and is the biggest dolphin. It is sometimes called the "wolf of the sea" because its behavior is similar to that of wolves.

Orcas grow to be about 27-33 feet (8-10 m) long, weighing more than 8,000-12,000 pounds (3.600-5.400 kg). The male orca is larger than the female. They are the largest member of the dolphin family.

The Orca's skin is mostly black with distinctive white patches. Orcas have stocky bodies and a rounded head with a distinctive beak. They have a tall, falcate (sickle-shaped) dorsal fin and large, paddle-like flippers. The dorsal fin of the male is taller (up to 6 ft tall) and more upright than that of the female (whose dorsal fin is up to 4 ft tall).

Orcas are efficient hunters that eat a very diverse diet of fish, squid, sharks, marine mammals (including whales and seals), turtles, octopi, and birds (penguins and gulls). They have even been known to attack young blue whales and other large whales. They have 10-13 pairs of large, interlocking conical, enameled teeth distributed in BOTH the upper and lower jaws (for a total of 20 to 26 pairs, so the orca has from 40 to 52 teeth). The teeth curve inwards and backwards - this helps the orca catch its prey. Teeth average about 3 inches (7.6 cm) long and about 1 inch in diameter, but some are even longer. Members of a pod frequently cooperate in hunts. An average-sized orca will eat 551 pounds (250 kg) of food a day.

Orcas live in small pods of 6-40 whales; they are very social animals. The bonds between the close-knit members of Orca pods are strong and last for life. The members of a pod hunt together in a very sophisticated manner, attacking even very large prey and then sharing it. The pod members protect the young, the sick and the injured.

Orcas can dive to a depth of 100 feet (30 m) in order to hunt. Orcas commonly breach (swim at very fast speeds toward the surface in order to rise above the surface of the water and then fall back onto the surface, splashing and making noise). Spyhopping (poking the head out of the water to look around) and tail slapping are also common orca activities. The purpose of these activities is unknown.

Orcas breathe air at the surface of the water through a blowhole located near the top of the head. Their blow is a single, low bushy cloud.

Orcas are very fast swimmers. They can swim up to 30 mph (48 km) in bursts in order to catch prey.

Orca vocalizations include clicks used in echolocation, whistles, and scream-like pulses. The sounds are used to communicate with other orcas, for mating purposes, and for locating prey. Different pods (long-lasting groups of orcas) have distinctive "accents" and can recognize members by this accent.

Orcas whales live in waters ranging from tropical to arctic, and both coastal and deep oceanic waters. They are found in all the world's oceans and most of the seas. Orcas sometimes enter estuaries, but don't go far from the sea.

Orcas don't make long, seasonal migrations. They may, however, cover an area of hundreds of miles (or kilometers) in order to find seasonal prey.

Orca breeding occurs mostly in the winter to early spring while near the surface and in warm waters. The gestation period is about 16-17 months and the calf is born tail first (this is normal for cetaceans) and near the surface, usually between October and March. The newborn instinctively swims to the surface within 10 seconds for its first breath; it is helped by its mother, using her flippers. Within 30 minutes of its birth the baby whale can swim. The newborn calf is about 6.5-8 feet (2-2.5 m) long, weighing up to 400 pounds (180 kg). Twins are extremely rare; there is almost always one calf. The baby is nurtured with its mother's milk. The mother and calf may stay together for a year or longer. Female orcas reach maturity at 6-10 years old, and males at 12-16 years old.

Male orcas have a life expectancy of 50-60 years. Females have a life expectancy of 90 years.

The species is in no danger as their numbers are abundant.

Orcas (Orcinus orca) are toothed whales (Suborder Odontoceti) They are one of 76 cetacean species, and are marine mammals. This species was named by Linnaeus in 1758.