Killer Whale

## Description

The Killer whale (Orcinus orca) is a toothed whale belonging to the oceanic dolphin family. It is the largest member of this family. The sophisticated hunting techniques and vocal behaviors of Killer whales have been described as manifestations of animal culture. They 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

Killer whales 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 bodies have an orange tinge.

## Distribution

Killer whales are considered a cosmopolitan species and occur in all oceans, from the Antarctic and Arctic regions to tropical seas. They also inhabit many inland or partially-enclosed seas, such as the Gulf of California, the Gulf of Mexico, the Mediterranean, the Arabian Gulf, and the Red Sea. In the Antarctic, Killer whales range up to the edge of the pack ice and are believed to venture into the denser pack ice, finding open leads much like beluga whales in the Arctic. However, they are merely seasonal visitors to Arctic waters and do not approach the pack ice in the summer. They usually prefer water 20 to 60 meters deep, but also travel through shallow waters along the coast. Migration patterns of KIller whales are poorly understood. Each summer, the same individuals appear off the coasts of British Columbia and Washington. Despite decades of research, where these animals go for the rest of the year remains unknown. Transient pods have been sighted from southern Alaska to central California.

## 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, and 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 sometimes called "wolves of the sea", because they hunt in groups like wolf packs. They spend most of their time at shallow depths, but occasionally dive several hundred meters depending on their prey. Killer whales spend their days foraging, traveling, resting, and socializing. They frequently engage in surface behavior such as breaching (jumping completely out of the water) and tail-slapping. These activities may have a variety of purposes, such as courtship, communication, dislodging parasites, or play. 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 to view their surroundings.

## Diet

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

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.