The killer whale belongs to the family of oceanic dolphins alongside pilot whales and melon-headed whales. It is considered one of the most widely distributed mammals after humans, with large populations of the species being seen in the near-freezing waters of the Arctic and Antarctic as well.
❍ The killer whale has a smooth, lustrous, streamlined body that is tapered at the ends. Male killer whales have an average length of 7 - 9 m and weigh over 6 tons. Females, on the other hand, are 6 - 8 m long and weigh in the range of 3 - 4 tons.
❍ The rounded forelimbs that they sport are called pectoral flippers. Their main function is to help them steer and stop; the latter also has flukes, i.e., the lobes of the tail, playing a crucial role. Their dorsal fin can be wavy, scarred, twisted, curved, or totally bent. It is believed that it helps them to be stable at elevated speeds.
❍ The black and white coloration of killer whales serves as a camouflage. When seen from the top, the black back mixes well with the dark water beneath. When seen from the bottom, the white belly blends with the sunlit water above.
❍ Killer whales are gifted with a keen ability to hear. They are known to react to sound in the range of 0.5 to 125 kHz. The sound waves are received by the soft tissue and bone near their ear. Above 50 kHz, the lower jaw works as an efficient receptor of sound waves.
❍ Besides that, these whales are also endowed with good vision, both inside and outside the water. However, they cannot smell and thus, have to rely on their hearing and vision.
❍ A group of killer whales is called a pod. A single pod may consist of anywhere between 5 - 30 individuals, including males, females, and young ones of diverse ages. These whales swim in a peculiar formation, wherein the females and young ones stay at the center of the pod, while the males are at flanks. Additionally, there are subpods consisting of maternal groups, i.e., a female and its young ones.
❍ At times, several pods unite to form larger groups called aggregations or herds. These groups may have 50 - 500 individuals. Further, pods in a specific region with similar dialects form what is known as a clan.
❍ Killer whales are among the most active predators in the marine environment. With no natural predators, they occupy the position of the apex predator in the marine biome food chain. They are the largest predators among warm-blooded animals.
❍ The diet of killer whale comprises sea lions, seals, squids, fish, penguins, otters, sea turtles, birds, walruses, polar bears, cetaceans, and even moose at times. Adults consume 3 - 4 percent of their body weight per day. Completely weaned calves need 10 percent of their body weight during the growth period.
❍ Their modus operandi is simple: surround the prey and attack it. If it's a large whale that they are pursuing, then the members of the pod attack it from various angles.
❍ Killer whales are polygamous, i.e., they have more than one mating partners at a time. Females attain sexual maturity at the age of 15 and breed until the age of 40, giving birth to an offspring once every 3 - 8 years. Even males attain sexual maturity at the age of 15, but they do not indulge in reproduction until they are 21.
❍ Summer is the common breeding season for the species. A calf is born after a gestation period of 17 months. At birth, killer whales measure around 2.6 m in length and weigh 260 - 350 lb. While the average lifespan for the species is 50 - 80 years, the mortality rate for the first six months is in the range of 37 - 50 percent.
❍ Speaking of killer whale attacks, neither can they be classified as 'fairly common', nor have there been human casualties as of now. In fact, it has been observed that captive orcas are more likely to attack humans than wild orcas, with several instances of them charging their handlers and intruders over the past few decades. If killer whales are so notorious, it's partly because of their common name and partly because of our ignorance about them.
The killer whale is enlisted as a data deficient species by the International Union for Conservation of Nature (IUCN), owing to the prevailing confusion about its classification. Like other species that inhabit the marine biome, even this species is battling oil spills, noise pollution, etc. Now that shouldn't really come as a surprise, considering that we seem to have made it our mission to make the marine biome uninhabitable for lifeforms.