Orca whales

DESCRIPTION

The orca whale, also known as the killer whale is a toothed whale that is a very focused predator, even attacking enormous young blue whales.

Their only enemies are humans. Orcas live in small, enclosed pods and have 1 blowhole. The killer whale belongs to the family of dolphins and it

is the biggest.

SIZEOrcas grow to be about 27-33 feet long, weighing more than 3600-5400 kg. The male orca is bigger than the female.

SKIN,SHAPE AND FINS

The Orca's skin is mostly black with outstanding white patches.

Orcas have rounded bodies and a rounded head with a rounded beak. They have a tall, pointy

dorsal fin and large, paddle-like flippers. The dorsal fin of the male is taller which is up to 6 ft tall and more upright than the dorsal fin of the female whose dorsal fin is up

to 4 foot tall.

SOCIAL GROUPSOrcas live in small groups of 6-40

whales, they are very social animals. The bonds between the close

members of Orca groups are strong and they last for life. The members of

a group hunt together in a very advanced manner, attacking even a very large prey and then sharing it.

The group members protect the young, the sick and the hurt.

  

DIET AND TEETHOrcas are task hunters that eat a very diverse diet of fish , squid , sharks , marine mammals (including whales and seals), turtles, octopus, 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 teeth in both the upper and lower jaws. So the Orca has from 40 up to 52 teeth. That is a total of 20 to 26 pairs of teeth.

The teeth curve inwards and backwards - this helps the orca catch its food and prey everyday. Teeth, on an average, are about 7.6 cm long and about 1 inch in diameter, but some are even longer. Members of a group always co-operate in hunts. An average-sized orca whale will eat 250 kgs of food a day.

The Food Chain of an Orca

Orca Seal Squid FishZooplan

ktonPhytoplankton

SPOUTING-BREATHING

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.

SPEEDOrcas are very fast swimmers. They can swim up to 48 km in bursts in order to catch prey.

HEARINGKiller whales have an acute sense of hearing, and the auditory cortex of the brain is well developed. killer whales have responded to tones within the frequency range of about 0.5 to 125 killer hertz. Peak sensitivity for killer whales is about 20 kHz. Sensitivity declines gradually above and below 20 kHz.

VOCALIZATIONOrca vocalizations include clicks, 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.

HABITAT AND RANGE

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.

 

LIFE SPAN: A male has an expectancy of 50-60

years. Females have a life expectancy of 90 years.

 

SOUND RECEPTION

Most sound reception, or hearing, probably takes place through the lower jaw.  A killer whale may also receive sound through soft tissue and bone surrounding the ear.  High frequency sounds in the range of 50 kHz and higher appear to be received effectively by the lower jaw.

The fat-filled lower jawbone conducts sound waves through the jaw to bones in the middle ears.  The lower jawbone of toothed whales widens and is hollow at the base, where it connects with the skull.  Within this very thin, hollow bone is a fat deposit that extends back toward the auditory ear bone complex. 

 

SOUND RECEPTION

Sounds are received and conducted through the lower jaw to the middle ear, inner ear, and then to hearing centres in the brain through the auditory nerve. Odontocetes can produce sounds for two overlapping functions, communicating and navigating. 

A killer whale can communicate and navigate at the same time. Sound waves travel through water at a speed of about 1.5 km/sec, which is four-and-a-half times as fast as sound travelling through air.  The sound waves produced by a killer whale bounce off objects in the water and return to the killer whale in the form of an echo.  

REPRODUCTIONOrca 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 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 2-2.5 m long, weighing up to 180 kg. Twins are extremely rare; there is almost always one calf. The baby is fed 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.

OVERALLWhales have sleek, streamlined bodies that move easily through the water. They are the only mammals, other than manatees, that live their entire lives in the water, and the only mammals that have adapted to life in the open oceans. Like all mammals, whales have lungs and they breathe air. They are warm-blooded, have a four-chambered heart, and nurse their young with milk from the mother. Unlike fish which swim by moving their tail left and right, whales swim by moving their flukes or tail flippers up and down.

CREDITSPowerpoint presentation by: Candice, Stacey and Olivia!

Information found by: Stacey, Olivia and Candice!

Pictures found by: Olivia, Candice and Stacey!

Music by: Candice, Stacey and Olivia!

BIBLIOGRAPHY

http://www.whalesfilm.com/orca.htm

http://www.worldwidewhale.com/orca.php 

http://www.seaworld.org/infobooks/KillerWhale/senseskw.html

http://www.enchantedlearning.com/subjects/whales/species/Orca.shtml