orca or killer

orca or killer

Orca (Orcinus orca) is the larger dolphin family member and is a versatile superpredator, which includes in its prey diet as fish, shellfish, birds, turtles, seals, sharks and animals larger when they hunt in groups, such as whales. Although "killer whale" is a misnomer, because it is a direct translation of the English "killer whale", and the fact that the animal is not a whale, it is commonly used. [2]. It is the second largest mammal of geographical distribution - right after the man - is found in all oceans and can weigh up to nine tons.

They have a complex social life, based on the formation and maintenance of large family groups. They communicate through sounds and usually travel in formations that loom occasionally to the surface. The first description of the species was made by Pliny the Elder which already described as a ferocious sea monster.

Name

The orca name was given to the animals by the ancient Roman name "Orcus", which means hell or god of death, and the name of their biological gender - "Orcinus" - means "the realm of death" (see Orcus). From the 60s, when they won popularity among viewers of aquariums, the neutral term "Orca" was used more than "killer whale", which connotes an incompatible behavior with the purpose of these parks.

Residents: 

The most commonly sighted of the three populations in coastal waters of the northeast Pacific, including Puget Sound. The diet of resident orcas mainly consists of fish and squid and live in complex and cohesive family groups. Family ties last a lifetime, often living in large matrilineal groups and making vocalizations in very variable and complex dialects. "The basic unit of orcas resident company is the parent, all of its dependent descendants (roughly ten years or less), as well as their adult offspring, including their children. Females may eventually spend less time with their mothers , as they are producing their young, but resident males seem to stay with their mothers their entire lives. they leave them for short periods to mate outside their maternal group, but return to their mothers after that. "[4] female residents characteristically have a rounded dorsal fin that terminates in a sharp corner. They are known to visit the same areas consistently. The resident populations of British Columbia and Washington, researchers identified and named over 300 Orcas over the past 30 years

Transient:

 The diet of these animals consists almost exclusively of marine mammals; they do not eat fish. In southern Alaska generally travel in small groups, usually two to six animals. Unlike residents, not always remain in their family units. The units consist of smaller groups with less permanent family ties and vocalizations in dialects less variable and less complex. Females have more triangular dorsal fins and pointed than the residents. The gray or white area around the dorsal fin, known as "saddle" often contains some black coloring in residents. In temporary populations are uniformly gray. These populations pass largely along the coast, and some individuals have been sighted in southern Alaska and later in California. On the coast of California, orcas gather in groups where attack gray whales, aiming to hunt prey on their young and elephant seals-Loons

Offshore (population at sea):

These animals were discovered in 1988 by researcher Jim Darling, who saw some orcas in the open sea. These cross the oceans and feed primarily on fish in shoals. However, the presence of scarred and damaged dorsal fins similar to those present in the hunting of passers hunting of mammals, shows the possibility that these eat mammals and sharks. They have been mostly found off the west coast of Vancouver Island and near the Queen Charlotte Islands. They were seen to travel in groups of 60 animals. Currently, little is known about the habits of this population, but can be distinguished genetically residents and temporary. Offshore seem to be smaller than the residents and in transit, and females are characterized by the dorsal fin tip which is rounded.

Types whale

• Type A

 is an orca "typical", who lives in open water and hunt mainly Antarctic minke whale. Along the coast of Argentina, orcas hunt individually with a technique of intentional grounding: they approach the beach and throw themselves on the sand to snatch sea lions. A specific and amazing phenomenon is that these orcas heading to the beach where they attack young lions and fur seals who are learning to swim.
Interestingly, this phenomenon happens in a very peculiar way, for the orcas literally "surf" down the beach to catch their prey, in what is known as "intentional grounding". However such a feat is very dangerous for a young and unprepared orca as it may run aground in the sand and die on the beach. So orcas mothers teach successive times puppies until they learn this risky game strategy.

• Type B

 is smaller than the Type A and inhabit the seas of Antarctica. It has a large eyepatch and a gray spot in the back, called "back cover". It feeds mainly focasque are on ice floes. One of the techniques most used by these orcas is to create waves to destabilize trapped in blocks of ice, knocking them into the water and then drag them to the tails and drown them. Sometimes, with luck, the seals manage to escape the sharp teeth of this giant of the seas.

•  Type C

is the lowest of all type and lives in groups larger than any other Orca. Its eyespot is distinctly bent forward rather than parallel to the body axis. As the type B has a back cover. Their only prey observed so far is the cod-of-Antarctica (Dissostichus mawsoni). Orcas type B and C live near the Antarctic ice cap, and the presence of diatoms in these waters may be responsible for the yellow color in two types. an investigation is being made in order to find out whether the orcas type B and C are different species.

• Type D

 has been identified based on photographs of a stranding orcas mass in 1955 in New Zealand and six appearances of people at sea since 2004. He is immediately recognizable by its extremely small eye white spot, a short dorsal fin and the bulbous head (similar to a pilot whale). Its geographical distribution seems to be circumglobal in sub-Antarctic waters between 40 ° S and 60 ° SE latitudes Although nothing is known about the diet of type D, it is suspected that include fish, because groups were photographed around palanqueiros where allegedly fishing the Patagonian toothfish (Dissostichus eleginoides).