Orcas: Killer Beauties

Habitat and Distribution

 

The habitat and Distribution.

Orcas can be found in both oceans, open sea and in coastal waters. The Orcas inhabit all the oceans of the world. They are very numerous in the Arctic, the Antarctic, and cold-water areas. Season icebergs limit the dispersion of the Orcas.

Migration.

The Orca migration is based on the migration of fish and other animals that they prey on, causing them to travel long distances. Another factor which have a great influence in their migration, is the birthing season, when they travel very long distances, in order to have their calves in safer waters.

 

A Spy hoping Orca in the freezing waters of the Artic.

Worldwide Population.

The worldwide population of the Orcas is not known. The population of Orcas in some specific areas has been calculated. For example, in some areas of the far Antarctic, their numbers are estimated to be about 180,000 units. This fact removes them from extinction danger. Several investigators agree that in some regions exist Orcas groupings.

An analysis of the Orca call sounds has demonstrated considerable differences within several different groups. Each family uses a different kind of "language" to communicate with their members.

Perhaps in the future, biochemical analysis of the chromosome characteristics can help to define a genetic relationship between groups and regional populations of Orcas. The sounds produced, the body form, and the coloration is used at the moment to identify separated Orca groups.

Investigators have learned recently, that to recognize many Orcas individually. Photographs can be used, especially of their dorsal fins. The "Photo-Identification" promises to be a very important new tool of investigation to study diverse aspects of the Biology of the cetaceans, including movements, reproduction, behavior, and population dynamic. "Photo-Identification" has the potential to document the life of the Orcas with great detail.

How does the "Photo-Identification" works?

1. Investigators take photos of the whale, when it raises to the surface to breathe. This exposes the marks on the animal's back and it's dorsal fin. Those marks are unique in each animal, as the digital fingerprints are unique in the humans.

2. When the photos are studied, Investigators look for subtle differences in the Orca body aspect. Those differences are what they use for identification, and they include:

• Dorsal fin form and relative lenght.

• Pigmentation Patterns.

• Scars.

• Deformations.

• Edge details of the dorsal fin, pectoral fins and flukes.

• Incrustations, and imperfections.

 

The investigators can individually identify Orcas, by recognizing the imperfections and marks of the dorsal fin. Note in this photo, the shape in form of ) that this Orca has in the superior part of its dorsal fin.

 

Transitory or Resident pods ? 

In the North Pacific, investigators have categorized two groups of Orcas: transitory and residents. In order to be able to do it, they based their investigations on the behavior and the size of the pod, and on their physical characteristics.

The size of the resident pods varies from 5 individuals to 50 individuals. The size of the transitory pods varies between 1 and 7 individuals.

The resident groups tend to travel within specific regions, whereas the transitory groups, without a defined region travel unpredictably. In the Pacific Northwest, there are two communities of resident groups: a northern community and a southern community. It is known that during migration, the northern community at rare time mixes with the southern community and vice versa.

 

This Orca belongs to a transitory group, which can be recognized by its preference towards other marine mammals. This photo shows an Orca near a marine lions group, hoping that some one of these marine mammals enters unwarned to the seawater.

 

The feeding preferences of the resident and the transitory groups differ. The resident groups eat an ample variety of fish and at rare times they look for marine mammals. The transitory groups on the contrary primarily eat the marine mammals and will occasionally eat fish. Research has shown that the resident groups have an ampler variety of sounds, than the transitory groups. However, the research continues.