The long-finned pilot whale Globicephala melas
The long-finned pilot whale is not actually a whale, but a dolphin. Long-finned pilot whales occur in temperate and subpolar zones. They are found in deep offshore waters and some coastal waters of the North Atlantic Ocean, including the Mediterranean Sea and North Sea. Long-finned pilot whales were previously found in the western North Pacific as well but appear to be absent there now. The circum-Antarctic subpopulations in the Southern Hemisphere occur as far south as 680S. Some populations always remain offshore, whereas others move into inshore waters in pursuit of prey. Long-finned pilot whales are migratory; they move over large areas throughout the year. They communicate by emitting a variety of sounds such as clicks, whistle, grunts and calls. When resting or "milling", simple whistles are emitted. Surfacing behaviour is accompanied by more complex whistles and pulsating sounds. Long-finned pilot whales also use vocalization for echolocation.
Most distinctive feature of the long-finned pilot whale is its very large bulbous, melon-shaped forehead. Initially, calves do not have the bulbous head. The melon grows as the calf matures. Mature male long-finned pilot whales are up to a metre longer than females, have thicker blubber, higher tail flukes, and more pronounced back ridge. The dorsal fin in these dolphins is quite low and long-based, and located relatively far forward on the back; the length of the dorsal fin comprises from l/4 to 1/6 of the animal’s body length. The long-finned pilot whale has only 40 to 48 teeth, compared to 120 in many other dolphin species. Long-finned pilot whales are mostly black, dark grey, or brown with a gray saddle patch behind their dorsal fin. Males can reach the length of up to 8.5 meters, with the average length being 6 meters, and can weigh up to 3,800 kg. Females are smaller; they reach a maximum length of 6 meters, with the average length being 4.8 meters, and can weigh up to 1,800 kg.
Long-finned pilot whales are highly social dolphins that live in groups (called “pods”) of 10 to 50 animals but sometimes aggregate in pods consisting of over 1,000 individuals. Each group is headed by a leader. There are usually a greater number of females in the pod, since males have a higher mortality rate and leave their pod after they reach sexual maturity. Long-finned pilot whales are carnivorous. They feed primarily on molluscs and fish, and eat about 35 kg of food a day. Their favourite food is squids but they also eat fish (cod, mackerel, and herring), small octopuses, and crustaceans. Nocturnally active, pilot whales tend to rest during the day. At nightfall, they start hunting, diving for up to 10 minutes to depths of up to 600 metres. Maximum registered speed of this species is 40.7 km/h.
The long-finned pilot whale is polygamous and mating takes place all year round, but the peak of the mating season is observed between April and June. Many offspring are not closely related to the pod males, suggesting that mating occurs between pods. Males display an aggressive courtship behavior, including colliding head to head at a high speed. After a gestation of almost 16 months, the female gives birth to a single calf measuring 1.4-1.8 metres and weighing about 100 kg.
Long-finned pilot whale young begin eating molluscs at the age of 6-9 months, but they are nursed for around 21 months and remain with their mothers for up to 2 years. Older and non-reproductive females assist in caring for calves in the social group. Young females reach sexual maturity at 6 to 7 years of age, when they are 350-370 cm long, whereas males do not become sexually mature until 12 years of age, when their body length is 490 cm. Pilot whales become fully grown (5.5-6 m) by the age of 18 to 20 years. Young pilot whales measuring 2-3 metres may gather in groups. Females at the late stage of pregnancy and lactating females often live in isolation. Large males and females may gather in one-sex groups. Oldest females can produce 9 offspring in the lifetime. Maximum longevity for males is 46 years, and for females is at least 60 years.
