Orca or
Killer Whale
Orcinus orca
Description
Killer whales (orcas) are large, stocky, and heavy! Their jet black, white
and grey markings, and the males' very tall dorsal fin, make them hard to
muddle up with other species. In fact, a male's dorsal fin can be as tall
as a man, up to 1.8m (6ft) high! It is the tallest dorsal fin in the
animal kingdom.
Researchers use the dorsal fins to identify
individual orcas. Different shapes, sizes, nicks and scars help them
remember which whale is which. Saddle-patches are also unique to
individual whales, no two orcas have exactly the same saddle-patch shape
and pattern. Different orca populations vary slightly from one another.
For example, those living in the Antarctic are smaller and their patches
more yellowy then those in the north, and those off Australia and New
Zealand are dark purplish-brown with ivory coloured patches.
An orca has between 20 and 26 large sharp teeth in both upper and lower
jaws; these curve backwards towards the throat and interlock when the
whale closes its mouth. They are perfectly designed for catching and
biting their food. |
Male |
|
Field ID:
Robust body, Single blowhole, Large paddle-like flippers, Black and white
in color, White chin, Grey saddle-patch, Tall dorsal fin, White patch
behind eyes, Fast active swimmer
Length (metres):
Orcas are the largest of all the members of the dolphin family. Adults can
range from approximately 5.5 to 9.8 meters (18 - 32.25 ft). Males are
larger then females, they average 7 - 8 metres, females around 6 metres .
New-borns are usually 2.1 to 2.5 meters (7 - 8.25 ft) long.
Weight:
Adults weigh anything from 2.6 to 9 tons (males are generally heavier then
females) and new-borns are approximately 180 kg (395lb)
Diet:
Fish, Squid, Seabirds, Turtles, Sealions, Seals, Other cetaceans
Behaviour:
Studies in northwest North America suggest that there are three kinds of
orcas (residents, transients and offshores), although orcas from other
parts of the world don’t always fit neatly into one of these categories.
Residents tend to form large family groups or pods (usually 5-25 animals).
They have relatively small home ranges (particularly in the summer) and
feed mainly on salmon and other fish. They normally hunt using
echolocation. Residents also 'talk' to one another more often than other
orcas. They are the most studied of all the orcas, because they have
predictable eating habits and are therefore relatively easy for scientists
to find and follow. The orcas of WDCS'
adoption scheme are residents.
Transients tend to form smaller family groups or pods (usually 1-7
animals). They tend to roam over a much wider area and feed on seals,
sealions, dolphins and other mammals, as well as seabirds and a variety of
other wildlife. They do not hunt using echolocation, probably because
their prey have good hearing and would be able to hear the orcas' clicking
sounds. Instead they swim quietly, listening to sounds being made by other
animals in the water. Transients 'talk' to one another less often then
resident orcas and have slightly more pointed dorsal fins. Offshores
were only identified for the first time in the early 1990s. They appear to
travel in large groups of 25 or more. Most of their time is spent in the
open sea, much further away from shore then either residents or
transients. They probably eat mainly fish and make lots of noise,
communicating with each other regularly.
Orcas can be very acrobatic. They are known to breach, lobtail,
flipper-slap and spy-hop. |
