Orka

• The orca can lift its head above water and listen for sounds to scout the shore. It surveys the surroundings and hunts prey using vision and hearing.
• The orca is the largest predator among cetaceans, hunting warm-blooded animals. It is the only modern representative of a genus that once included another species, Orcinus citoniensis.
• The mother orca pushes the calf onto shallow water or land to teach it how to handle prey on shore. If the calf panics, she surfaces and drags it, repeating the lesson until confident behavior.
• Orcas attack female sperm whales, trying to prevent them from diving deep, but avoid males because their strength is great and their jaws can inflict fatal wounds. During attacks, they bite the victim's throat and fins, trying to prevent it from surfacing.
• Female orcas can hunt large white sharks using hunting techniques. The shark is not much smaller than the orca itself.
• Female orcas experience menopause and live many decades after losing the ability to reproduce. This period begins around the age of forty, when they stop giving birth to calves.
• Transient orcas produce fewer sounds because marine mammals can hear them. According to the theory, they orient by passively listening to ocean noises, unlike residents.
• The orca can hear sounds up to 100 kHz, although its highest sensitivity is at 20 kHz. A 1999 study showed that both examined orcas responded to sounds at this high frequency.
• Resident and transient orcas do not interbreed, and this has not changed for at least 100,000 years. Genome analysis showed no interbreeding between them over the last 100,000 years.
• Male orcas reach lengths of 10 m and weights up to 8 t, while females reach up to 8.7 m. Males' dorsal fins reach heights of up to 1.5 m and are almost straight.
• Orcas use complex tactical schemes for hunting, employing them in groups. Groups form a line and swim at a speed of about 5 km/h.
• Orcas attack ships, even if they are larger than the orcas. Experience studying cases showed they attack ships, not people, perceiving them as independent objects.
• The orca's head is short, flattened on top, without a beak, and its teeth are massive, up to 13 cm long, adapted for tearing large prey. Such teeth allow it to efficiently tear the bodies of large marine animals.
• The average lifespan of an orca is 50 years for males and 75–100 years for females. In captivity, these numbers decrease two- to threefold.
• Orcas cooperate with dolphins during hunting, following them coordinatedly to depth and reducing echolocation, guided by dolphins' acoustic signals. Orcas share caught fish with group members, while dolphins consume food leftovers.
• The pattern of spots on an orca is so individual that it allows identifying individual animals. In Arctic and Antarctic waters, white spots may take on a yellowish-green or brownish tint due to diatom algae films covering them.
• Killer whales attack not only out of hunger or territory defense. They become irritable and aggressive also during the breeding period.
• Mating in killer whales occurs when related groups unite. All members of one group are related to each other.
• The duration of pregnancy in killer whales is not precisely established, although it is believed to last 16–17 months. Mating occurs in summer months and early autumn.
• A male killer whale may kill an offspring to provoke the mother’s interest in another conception. This happens to restart her cycle, the male is trying to achieve.
• Killer whales have a complex social organization, which is surpassed in complexity of internal and external social bonds only by the social structures of elephants and higher primates. Their basis is a matriarchal group, usually consisting of a female with offspring of different ages and adult sons.
• Killer whales attack humans not out of hunger, but due to stress and loneliness in captivity. Attacks occurred when they were separated from spouses and offspring or due to lack of a partner during the mating season.
• A killer whale may express dissatisfaction by slapping the tail or pectoral fins. In the most extreme case, the disturbed individual does this.
• After a killing, a killer whale allows others into the pool so they can remove the body of the deceased victim. After some time, she again approaches humans.
• Killer whales hunt seals by setting ambushes and using the seabed topography near haul-outs. Only one male attacks, while the other killer whales wait at a distance.
• Killer whales herd fish into a tight ball and stun them with tail slaps. This hunting technique requires a pod of 5 to 15 individuals.
• The upper hearing threshold of a killer whale is 31 kHz, much lower than that of dolphins. Its most sensitive hearing range is 5–30 kHz.
• Killer whales have a unique vocal dialect that includes both sounds common to all killer whales and sounds specific to their pod. Each pod has its own set of sounds.
• Killer whales create a directed wave with powerful tail flukes to wash prey into the sea. When hunting seals or penguins on ice, they line up and move flukes synchronously.
• A killer whale can sink a ship if it delivers a strong blow to the hull. A leak caused by such a blow led to the sinking of a wooden-hulled ship 320 km from shore.
• Healthy killer whales care for old, sick, or injured pod members. Sexual maturity occurs around 12–14 years of age.