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Newborn 2.1 - 2.5 m (7 - 8 1/2 ft), 180kg (395 lb)
Adult 5.5 - 9.8 m (18 - 32 1/4 ft), 2.6 - 9 tons
Males are longer and bulkier than females, average length 7.3m (24ft)
as compared to females 20 1/4ft, males also have much taller and
straighter dorsal fins.
Residents: Mostly salmon.
Transients: Seals, Sea Lions, other whales, birds, & Penguins.
It's common name , recognized by many people, is killer whale (originally
called "whale killer" by Spanish whalers). It's scientific name
is Orcinus Orca. The Romans called it "Orca," meaning "demon from
hell".
Males can grow up to approx. 32 ft. in length and can weigh in at
10 tons. Females can grow up to approx. 27 ft. in length and can
weigh in at 7 tons. Newborn calves are approx. 7 ft. in length and
weigh in at almost 400 lbs. upon birth.
Killer whales inhabit all the oceans of the world. They
are most numerous in the Arctic, the Antarctic, and areas of cold
water upwelling. Killer whale distribution is limited by seasonal
pack ice.
Killer whales are found in both the open ocean and coastal waters.
Migration of fish and other prey accounts for movements of killer
whales to and from certain areas.
The worldwide population of killer whales is unknown. Specific killer
whale populations in a few areas have been estimated. For instance,
in some areas of the Antarctic alone, their numbers are estimated
at about 180,000. Killer whales are not endangered. Most researchers
agree that regional groupings of killer whales exist. Analysis of
killer whale call patterns has demonstrated substantial differences
between the sound repertoires of different pods. In the future,
analyzing biochemical and chromosomal characteristics may help define
genetic relationships among pods and regional populations of killer
whales. Call patterns, body shape, and coloration are currently
used in identifying separate killer whale populations.
Researchers have recently learned to recognize many individual killer
whales from photographs, especially of their dorsal fins. Photo-identification
promises to be an important new research tool for studying various
aspects of cetacean biology, including movements, reproduction,
behavior, and population dynamics. Photo-identification has the
potential to document the lives of individual whales in great detail.
Researchers take photographs when the whale rises highest out of
the water as it breathes normally and exposes the most markings
on the back and dorsal fin. Studying the photos, these researchers
must be skilled at recognizing subtle differences in whales' body
appearance. The features they use for identification include dorsal
fin shape and relative size, pigmentation patterns, scars, deformities,
detail of tail fluke edges, encrustations, and blemishes. Researchers
can identify individual killer whales by recognizing differences
in the appearance of the dorsal fin and saddle.
In the North Pacific, researchers categorize pods of killer whales
into transient-type whales and resident-type whales, based on physical
and behavioral characteristics. The size of resident pods varies
from as few as 5 to as many as 50 individuals. Transient pod size
varies between 1 and 7 individuals. Resident pods tend to travel
within specific ranges while transient pod ranges are unpredictable.
In the Pacific Northwest, there are two communities of resident
pods: a northern community and a southern community. Food preferences
of resident and transient pods differ. Resident pods eat a wide
variety of fish and rarely seek out marine mammals. Transient pods
primarily eat marine mammals and will occasionally eat fish. Research
has shown that resident pods have a wider sound repertoire than
transient pods.
Calves are born throughout the year. Gestation is about
17 months.
Based on limited data collected from populations at sea, a female
may bear a calf every five years.
Calves are born in the water. Deliveries can be either tail-first
or head-first. The umbilical cord snaps during or soon after delivery.
The calf is about 8 ft. (2.4m) long and weighs about 300 to 400
lb. (131-181 kg).
The light areas of some young killer whales may be creamy white
to lemon yellow rather than white. This color usually turns white
by the age of one year. In the first few days after birth, the dorsal
fin and tail flukes gradually stiffen.
The calf suckles from nipples concealed in abdominal mammary slits.
Killer whale calves begin nursing several hours after birth. Calves
nurse below water, close to the surface. The mother glides in a
horizontal position with her tail arched, and the calf swims on
its side with its mouth on the right or left mammary gland. Calves
nurse for about 5 to 10 seconds at a time, several times an hour,
24 hours a day. The mother's milk is very rich so that the baby
rapidly develops a thick, insulating layer of blubber. The fat content
of the mother's milk increases as the calf develops. It ranges from
about 28% to 48%. A calf may nurse for 12 months. A mother killer
whale stays close to her calf and attentively directs its movements.
The baby swims close to its mother and can be carried in the mother's
"slip stream," a type of hydrodynamic wake which develops as the
mother swims. This helps the baby swim with less energy and enables
the mother and calf to keep up with the pod. While most maternal
behavior is probably instinctive, first-time mothers are inexperienced
at nursing their calves. The experience level of some first-time
pregnant females is increased through training procedures that teach
them to respond to nursing behavior. To nurse, a calf swims on its
side and suckles from nipples concealed in abdominal mammary slits.
Killer whale breeding colonies in marine zoological parks continue
to provide a unique opportunity to observe and quantify aspects
of their biology. A killer whale calf's upper teeth erupt at about
two to four months. The lower teeth erupt at about three to five
months. Calves begin to take a few fish at about three to four months.
They eat solid food consistently at about four to five months. By
the age of one year, calves can eat 50 to 60 lb. (23-27 kg) of herring,
smelt, and squid every day. Calves grow about 2.6 ft. (80 cm) during
their first year, and about 2.2 ft. (67 cm) during their second
year. Calves can vocalize within days of birth, but sound production
is shaped with age. In studies, scientists have determined the following.
Vocal behavior is not predetermined. Calves learn during the course
of development which calls to make and under what circumstances.
Calves are most likely to develop calls like those of their closest
associates (usually the mother). Stereotyped calls develop between
5 months and 1 year of age.
Studies of killer whales in marine zoological parks suggest that
females become sexually mature when they reach about 15 to 16 ft.
(4.6-4.9 m), at about 6 to 10 years. Males become sexually mature
when they reach about 18 to 20 ft. (5.5-6.1 m), at about 10 to 13
years. Comparably collected field data is not available.
Females come into estrus or "heat" several times during the year.
Breeding may occur in any season, but is most common in summer.
In the North Atlantic, mating seems to peak in October and November;
in the western North Pacific, mating seems to peak between May and
July.
Killer whales are the top predators in the ocean. They are active
predators. Opportunistic feeders, their diet varies from one region
to another. In the Antarctic, killer whales eat about 67% fishes,
27% marine mammals, and 6% squids. Killer whales in the Bering Sea
(near Alaska), eat about 65% fishes, 20% squids, and 15% marine
mammals. Food preferences of resident and transient pods in the
North Pacific differ. They eat a variety of fish, including salmon,
cod, flatfish, hake, herring, and smelt. They also eat other marine
mammals and seabirds. Killer whales prey on both mysticete and odontocete
whales, seals, sea lions, walruses, and occasionally sea otters
and penguins.
Adult killer whales eat approximately 3% to 4% of their body weight
in food per day; fully weaned calves can eat up to approximately
10% of their body weight during growth periods.
Much like packs of wolves or prides of lions, killer whales often
hunt cooperatively in pods for food. They work together to encircle
and herd prey into a small area before attacking.
Killer whales often hunt cooperatively. Killer whales may slide
out on sand bars or ice floes to pursue prey. They may also surface
under ice floes to knock prey into the water. Killer whales don't
chew their food. They swallow their food whole or tear it into large
chunks.
Killer whales live in groups called pods. The size of a pod usually
varies from less than 5 to about 30 individuals. A pod is a cohesive
long-term social unit. A pod usually consists of males, females,
and calves of varying ages. Several smaller pods may join occasionally
to form larger groups of 50 or more individuals called herds or
aggregations. There is an occasional exchange of members between
pods, especially during breeding season.
Killer whales in a pod appear to establish strong social bonds.
Behavioral studies suggest that certain animals prefer associating
with one another. As with most species, there is a social hierarchy
within a group of killer whales. This social hierarchy is female-dominant.
The animals may rank themselves and establish dominance by slapping
their tails against the water, head-butting, jaw-snapping, and various
other vigorous postures and gestures. Killer whales often hunt together.
Killer whale behavior includes spyhopping (hanging vertically in
the water with the head partially above water), breaching (jumping
clear of the water and landing on the back or side), lobtailing
(slapping the tail flukes on the surface of the water), and pec-slapping
(slapping a pectoral
Killer whales have been known to mass strand. As with other whales,
the reason for these strandings is unknown. Stranding is not the
same as intentional beaching for pursuing prey.
Other marine mammals, such as minke whales, Dall's porpoises, and
seals, have been observed swimming with killer whales, but they
may be prey of killer whales at other times.
Killer whales have a well-developed, acute sense of hearing. The
auditory cortex of the brain is highly developed. Killer whales
have responded to tones within the frequency range of about 0.5
to 100 kHz. (The average hearing range for humans is about 0.02
to 17 kHz.). Peak sensitivity is about 15 kHz.
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. The fat filled lower jawbone conducts
sound waves through the jaw to bones in the middle ears. The fat-filled
lower jawbone appears to conduct sound waves through the jaw to
bones in the middle ears. The lower jawbone of toothed whales broadens
and is hollow at the base, where it hinges with the skull. Within
this very thin, hollow bone is a fat deposit that extends back toward
the auditory bulla (earbone complex). Sounds are received and conducted
through the lower jaw to the middle ear, and then to hearing centers
in the brain via the auditory nerve. A killer whale does have small
external ear openings, a few inches behind each eye. Each opening
leads to a reduced ear canal and an eardrum. Some scientists believe
that killer whales receive sound through these openings. Other scientists
believe that a killer whale's external ear openings are nonfunctional.
A foam surrounds the ear bone on all sides. This foam contains air.
Air stops sound waves traveling through water and living tissues.
Many scientists believe that this foam accoustically isolates the
ears, enabling a killer whale to tell which direction a sound comes
from.
Killer whales have acute vision both in and out of the water. The
eyes, about the same size as the eyes of a cow, are on each side
of the head, just behind and above the mouth. Glands at the inner
corners of the eye sockets secrete an oily, jellylike mucus that
lubricates the eyes, washes away debris, and probably helps streamline
the eyes as a killer whale swims. This tearlike film may also protect
the eyes from infective organisms.
Features of the brain indicate that a killer whale's sense
of touch is well developed. Killer whales' skin is sensitive to
touch.
Little is known about a killer whale's sense of taste. They do have
taste buds, although they haven't been well studied.
Olfactory lobes of the brain and olfactory nerves are absent in
all toothed whales, indicating that they have no sense of smell.
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