Common Name: Killer Whale or Orca
belong to the Mammalian Order Cetacea, in the suborder Odontoceti.
All toothed whales belong to the suborder Odontoceti, which is Latin
for "toothed whales". The orca is the largest member of the oceanic
dolphin family, Delphinidae. Other members of this family include
the bottlenose dolphin, long-beaked common dolphin, and pilot
whale. The orca's scientific name is Orcinus orca, which
means "whale-like whale".
whales are black with white eye patches, white side patches, and a
white underbelly. A gray patch posterior to the dorsal fin is
called the "saddle patch". Males are larger than females, exceeding
lengths of 30ft and weights of 8-9 tons. Females usually attain
lengths of about 20ft, and weights of four tons. Adult males are
also distinguished from females and juvenile males by their very
large dorsal fins. Females and young whales have curved dorsal
fins, usually no taller than three feet. Adult males however, have
six foot tall, triangular dorsal fins. These dorsal fins are the
largest of all whales.
intelligence of orcas is widely known. Marine parks throughout the
world display killer whales as main attractions. Orcas perform a
wide variety of learned behaviors in marine shows. Such playful
interactions between orcas and humans has lead to the misconception
that orcas are gentle animals of the ocean. Killer whales are
appropriately named. They fiercely attack prey in cooperative
hunting groups, feeding on a wide variety of prey.
are found in all oceans of the world. Such a wide distribution
implies a varied diet. Killer whales feed on a large variety of
marine animals. Thirty fish species, including salmon, herring, and
shark species are hunted. Even the largest shark, the whale shark,
falls prey to the orca. Five seal species, seven seabird species,
sea lions, penguins, squid, sea otters, and sea turtles are common
prey. Larger aquatic mammals, like dugongs are also hunted.
Fascinatingly, 24 different species of cetacean are hunted by
orcas. Dall's porpoise isn't even fast enough to escape the orca.
The enormous size of baleen whales is not a deterrent either. In
fact, orcas seem to enjoy the baleen whale tongue. After slowing
down a much larger baleen whale by biting its fins and flukes, a
killer whale pod will devour the tongue. Eating to their fill, the
orcas then leave the remainder of the carcass. Successful attacks
on sperm whales, the largest species of toothed whale have been
documented. Their wide distribution, variety of prey, group hunting
technique, and aggressive hunting tactics have given rise to the
nickname "wolves of the sea".
Distinct populations of wild orcas exist. This has lead to the
development of characteristic vocal dialects and hunting techniques
within populations. While geographical location has a large part in
the prey species an orca may hunt, some orca pods in the same region
hunt different animals. For example, two types of orcas live in the
waters of the North American Pacific Northwest. One type feeds
primarily on fish species, mainly the Pacific salmon. These killer
whales are called "resident" orcas. They do not travel far from
this region, remaining there to feed on the continuous supply of
local fish. The second type of orca in this area feeds primarily on
other marine mammals. Harbor seals, gray whale, and harbor porpoise
are just a few potential prey species. These killer whales travel
along the coast of North America, tapping a variety of different
food sources. The cause of differentiation between orca pods, and
their relationships with one another are still unknown.
Incidentally, a third type of orca pod occasionally visits the
Pacific Northwest. Researchers refer to these pods as "offshore"
orcas. Little is known about where, what, or how they hunt, but it
is assumed they have different techniques from the resident and
social structure of such pods differs as well. Resident orca pods
are matrilineal and very stable. Orcas in these pods remain with
their mothers their entire lives. Transient pods are more fluid,
with mother and calf pairs entering and leaving pods. The structure
of offshore pods is currently being studied. The year round
presence of calves leads scientists to believe that orcas may breed
all year. After a gestation period of 16 months, a female orca
gives birth to a single calf. The calf is about six feet long,
weighing 300-400lbs. The calf will remain with its mother for 3-7
years. A single female gives birth about every 8 years. Females
become sexually mature at 9-12 years of age. Males reach sexual
maturity at 13-16 years. Male puberty is characterized by the
growth of pectoral and dorsal fins. Called "sprouting", the male's
juvenile curved dorsal fin grows much larger and straighter. His
pectoral fins also become larger. Females live longer than males,
aging 80 years. Males live well into their fifties.
The global population of
orcas is unknown. It is estimated by some to be at least 100,000.
They have no natural predators. Whalers did not hunt orcas as
thoroughly as other whale species. Orcas rely on fish directly, as
their primary food source, or indirectly, eating marine mammals that
feed primarily on fish. Overfishing is therefore a threat to
orcas. Less available food resources will result in less orcas.
Water pollutants are dangerous to all cetaceans, the orca being no
exception. A decrease in water pollution and commercial fishing aid
in killer whale conservation.