The orca whale's large size and strength make it among the fastest marine mammals, able to reach speeds in excess of 30 knots (about 34 mph, or 56 kph).
Credit: Orca image via Shutterstock
Orcas are often called killer whales. Though they don't typically attack humans, this name is still well-chosen due to the animal's ability to take down large marine animals, such as sea lions and whales. In fact, orcas will prey on almost any animal they find in the sea, in the air over the water or along the coastline. To hunt, killer whales use their massive teeth, which can grow up to 4 inches (10 centimeters) long.
Orcas are known for their long dorsal fin (the fin on the animal's back) and black-and-white coloring. Just behind the dorsal fin is a patch of gray called a "saddle" — because it looks like a riding saddle. An orca's body is cylindrical and tapers at both ends to form an aerodynamic shape.
According to National Geographic, orcas are considered the largest species of the dolphin family. They weigh up to 6 tons (5,443 kilograms) and grow to 23 to 32 feet (7 to 9.7 meters). That is almost as long as a school bus. The largest orca ever recorded was 32 feet (9.8 m) long, according to Sea World.
Killer whales are the most widely distributed mammals, other than humans, according to Sea World. They live in the oceans and seas surrounding most coastal countries. They adapt very well to any climate. For example, they can live in the warm waters near the equator or the icy waters of the North and South Pole regions. Orcas are more likely to be found at higher latitudes and near the shore, though. [Gallery: Russia's Beautiful Killer Whales]
These animals do not stay in one area and have been documented traveling long distances. For example, one study found a group of orcas traveling all the way from the waters off of Alaska to those near central California, according to International Union for Conservation of Nature's (IUCN) Red List. This is a distance of more than 2,000 kilometers (more than 1,200 miles).
Orcas are very social and live in groups called pods, which usually have up to 40 members, according to National Geographic. There are two different kinds of pods: A resident pod is less aggressive and tends to prefer fish. Transient pods act much like wolf packs and are much more aggressive. They hunt marine mammals by working together. [Video: Killer Whales Caught in Stunning Drone Footage]
Orcas are apex predators, at the top of the food chain. No other animals (except for humans) hunt orcas. Killer whales feed on sea birds, squid, octopuses, sea turtles, sharks, rays and fish. They also eat most marine mammals, such as seals and dugongs. The only exceptions are river dolphins and manatees, according to the IUCN. Killer whales have also been reported to eat moose, according to Sea World.
Orcas use many different techniques to catch prey. Sometimes they beach themselves to catch seals on land, meaning they jump from the water onto land. Orcas will also work together to catch larger prey or groups of prey such as schools of fish.
Killer whales also work together to take care of the young in a pod. Often, young females will help the mothers care for young orcas
A female killer whale will give birth every three to 10 years, to one offspring at a time. The gestation period usually lasts for around 17 months. A baby orca is called a calf, and they are about 8.5 feet (2.6 m) long and 265 to 353 lbs. (120 to 160 kg) at birth, according to Sea World. Calves nurse for 5 to 10 seconds at a time, several times an hour. This goes on day and night until the calf has mature enough. It is weaned at a year old. Orcas can live from 50 to 100 years.
According to the Integrated Taxonomic Information System (ITIS), orcas are in the same family as dolphins and pilot whales. The taxonomy of orcas is:
- Kingdom: Animalia
- Infrakingdom: Deuterostomia
- Phylum: Chordata
- Subphylum: Vertebrata
- Infraphylum: Gnathostomata
- Superclass: Tetrapoda
- Class: Mammalia
- Subclass: Theria
- Infraclass: Eutheria
- Order: Cetacea
- Suborder: Odontoceti
- Family: Delphinidae
- Genus & species: Orcinus orca
The National Oceanic and Atmospheric Administration (NOAA) notes that recent genetic studies have led many cetacean biologists to hypothesize that multiple species or subspecies of killer whales exist worldwide.
Three distinct forms, or ecotypes, of killer whales are recognized: resident, transient (or Bigg's) and offshore. The ecotypes differ in dietary needs, behavior patterns, social structures and habitat preferences, as well as in genetics, size and shape, according to the NOAA's Office of Protected Resources. And the IUCN notes, "The taxonomy of this genus is clearly in need of review, and it is likely that O. orca will be split into a number of different species or at least subspecies over the next few years."
According to the IUCN, the orca's population is unknown, and therefore the organization cannot label the animal's conservation status, though some populations are protected, according to the NOAA.
Civilizations around the world kill orcas for various reasons. Some people kill them for food, while fishermen see the animals as competition that must be killed to protect the fish population. Contaminants in the ocean and seas, such as chemicals and oil, also pose a threat to orcas.
Orcas use echolocation to talk to each other and hunt. They will make a sound that travels through the water until sound waves hit an object. Then, the sound wave will bounce back to the orca. Using this technique, they are able to detect where objects and other orcas are in the area. They can also find out the size and shape of an object using echolocation.
When orcas are born, their dorsal fin is flexible, but it stiffens as the calf ages.
Orcas are black and white for a reason; their coloring helps to camouflage them by obscuring their outline in the water.
- National Geographic: Killer Whales
- Sea World: Killer Whales
- NOAA Office of Protected Resources: Killer Whale