The Orca is the largest species in the Mammalia and dolphin family.

The Orca is the only recognized species in the genus Orca and one of the many animal species originally described by Linnaeus in the Systema Naturae in 1758.

After examining a stranded and dead animal in Greifswald Bay, Conrad Gesner gave the first scientific description of orcas in his 1558 book The World of Fish and Aquatic Animals, which attracted great local attention. 

The Orca is one of 35 species in the marine dolphin family that first appeared about a million years ago.

Soon thereafter, there were branches of the orca lineage. Richard LeDuc's study of the cytochrome b gene sequence showed that although it is morphologically similar to the pseudotigers, minke whales, and pilot whales, its closest relative is the Australian short flat-nosed dolphin of the genus Iguana.

However, a 2018 study included the Orca as a sister taxon of the dolphin subfamily, which includes the genera Spotted Dolphin and Dwarf Dolphin.

Orcas have cone-shaped heads and no prominent mouth bill.

There is a clear sexual dimorphism in body size, flipper size, and dorsal fin height. The towering dorsal fin is located in the center of the back and is 1.0-1.8 m tall in male adults, while in females it is distinctly sickle-shaped and less than 1 m tall.

The pectoral fins are large, broad, and roughly circular. The upper and lower jaws each have 10-14 pairs of large, sharp teeth.

The body color pattern of the Orca consists mainly of two contrasting colors, black and white, with the white area on the ventral side of the body extending backward from the lower jaw to the tail, narrowing between the all-black pectoral fins and diverging behind the navel, and the ventral side of the caudal fin is also white.

The dorsum and sides of the body are black, but there are white patches on the lateral ventral area near the genital fissure and a distinct oval white patch behind the eye. There are gray to white saddle-like markings on the posterior side of the dorsal fin.

The Orca is a highly social animal, with some of the most stable families in the animal kingdom. Orca teaches members through apprenticeship. Hunting and offspring rearing are among the skills taught to young whales.

Some of the orcas' complex social behaviors, hunting techniques, and vocal communication are considered evidence that orcas have a culture of their own.

They are carnivorous, fierce, and aggressive in attacking their prey, and are natural enemies of penguins, dolphins, seals, and other animals. Sometimes they attack other cetaceans, even great white sharks, and can be considered the king of the sea.

The habitat of the Orca is mainly polar and temperate waters. There seem to be no obvious restrictions on water temperature, depth, and other factors.

Usually preferring depths of 20-60 meters, they can also visit shallow waters along the coastline or dive up to 300 meters in search of food. Orca is found in almost all areas of the ocean, from the equator to polar waters.

There is no limit to their range by water temperature or depth. The distribution extends to many enclosed or semi-enclosed seas such as the Mediterranean Sea, the Sea of Okhotsk, the Gulf of California, the Gulf of Mexico, the Red Sea, and the Persian Gulf.

Orca can be divided into different ecotypes according to their habitat and habits, which differ slightly in appearance and habits.

Orcas have a high IQ and can recognize that humans are different from other marine animals, so a normal Orca will not harm humans.

Except for humans, adult orcas do not have any natural enemies in the sea, but orcas have become the natural enemies of many other animals, and they can even prey on great white sharks or blue whales.

As the world's largest mammal, the larger adult blue whale can reach 33.5 meters in length and weigh more than 180 tons, close to the weight of 30 elephants. Such a huge body, in front of the Orca group, can only fall away, turn around and flee.