Killer Whale

## Description

The orca or killer whale (Orcinus orca ) is a toothed whale belonging to the oceanic dolphin family, of which it is the largest member. It is recognizable by its black-and-white patterned body. A cosmopolitan species, orcas can be found in all of the world's oceans in a variety of marine environments, from Arctic and Antarctic regions to tropical seas.

Orcas have a diverse diet, although individual populations often specialize in particular types of prey. Some feed exclusively on fish, while others hunt marine mammals such as seals and other species of dolphin. They have been known to attack baleen whale calves, and even adult whales. Orcas are apex predators, as they have no natural predators. They are highly social; some populations are composed of very stable matrilineal family groups (pods) which are the most stable of any animal species. Their sophisticated hunting techniques and vocal behaviours, which are often specific to a particular group and passed across generations, have been described as manifestations of animal culture.

The International Union for Conservation of Nature assesses the orca's conservation status as data deficient because of the likelihood that two or more orca types are separate species. Some local populations are considered threatened or endangered due to prey depletion, habitat loss, pollution (by PCBs), capture for marine mammal parks, and conflicts with human fisheries. In late 2005, the southern resident orcas, which swim in British Columbia and Washington waters, were placed on the U.S. Endangered Species list.

Wild orcas are not considered a threat to humans, and no fatal attack on humans has ever been documented. There have been cases of captive orcas killing or injuring their handlers at marine theme parks. Orcas feature strongly in the mythologies of indigenous cultures, and their reputation in different cultures ranges from being the souls of humans to merciless killers.

## Appearance

The Killer whale or orca is one of the toothed whales and the largest member of the dolphin family. They have long, round bodies with big dorsal fins in the middle of their back. Their bodies are black with white patches underneath and near their eyes. These distinctive patterns help to camouflage them when they are searching for food. In newborns, the white parts of their body have an orange tinge.

## Distribution

Killer whales are considered a cosmopolitan species and occur in all oceans, from Antarctic and Arctic regions to tropical seas. They also inhabit many inland or partially-enclosed seas, such as the Gulf of California, Gulf of Mexico, Mediterranean, Arabian Gulf, and the Red Sea. They usually prefer water that is 20 to 60 meters deep, but also travel through shallow waters along the coast or dive as deep as 300 meters when searching for food.

## Behavior

Killer whales are highly social animals; they are active during the day and sleep at night. They travel in pods of between 3 and 50 individuals, led by females. They establish social hierarchies. Individuals in pods are usually related to each other and consist of about 20% adult males, 20% calves, with the rest being females and young males. They have limited dispersal from their maternal pod. Killer whales may share prey and seldom leave the pod for longer than a few hours. Pod members learn skills through apprenticeships, such as hunting and parenting. Killer whales are very vocal animals and communicate with each other using whistles and clicks via echolocation, and through physical behavior such as breaching, slapping their tail or flippers, and ‘spyhopping’, when they lift their head above the water.

## Diet

Killer whales are predators at the top of the food chain and prey upon a wide range of large prey including seals, smaller whales and dolphins, sea lions, different fish, sharks, squid, octopi, sea birds, and sea turtles, sea otters, and river otters.

## Reproduction

Killer whales are polygynandrous (promiscuous), with both males and females having multiple mates throughout a breeding season. They do not interbreed within their own pod but with individuals from another pod. Mating occurs at any time throughout the year, usually in summer. After a gestation of 15-18 months, a female gives birth to one calf. The young will feed from their mothers for as long as 2 years, but at 12 months will start to eat solid food. Mothers teach their calves how to hunt and they include them in their pod's social network. Calves stay with their birth pod after they gain independence. Females become reproductively mature when they are 15 years old and will give birth once every 5 years until the age of 40. Males reach reproductive maturity when they are about 15 years old, but usually do not reproduce until 21.

## Population

### Population threats

The greatest threat to these whales comes from degradation and disturbance of their habitat. Being at the top of the food chain, the Killer whale is vulnerable to contaminants accumulating in its tissues, such as the high levels of PCBs (polychlorinated biphenyls) found in some populations, with potentially negative impacts on its reproduction and survival. Extensive oil spills can affect these animals, either directly or indirectly, in that it reduces the number of their prey. Disturbance by boats and other underwater noises caused by humans can affect their behavior, disrupt social calls and echolocation, and impact the ability of Killer whales to effectively forage in places where whale-watching is increasingly popular. Boat traffic also increases the risk of injuries from collisions.

### Population number

According to the IUCN Red List, the worldwide population of the Killer whale is estimated to be around 50,000 whales. This species is currently classified as Data Deficient (DD) on the IUCN list of threatened species.

## Fun Facts for Kids

Killer whales don't typically attack humans, but they have this name because of their ability to take down large animals, such as other whales and sea lions. They will prey on nearly any animal in the sea, in the air above them, or along the coastline.

Romans gave these whales the name "orca" and it has become popular over the years.

When orcas are born, they have a flexible dorsal fin, which stiffens as they grow older.

In the 1960s orcas made their enormous debut splash in marine shows.

The most popular movies that have featured Killer whales include Happy Feet, Free Willy, and Namu: The Killer whale.

These whales have a brain that is the second largest of all marine mammals and is second to only the sperm whale which has the largest brain out of any living animal.