Pilot whale

Pilot whales are large marine mammals belonging to the genus Globicephala. They are members of the dolphin family and are often called blackfish. Among the oceanic dolphins, they are among the largest, surpassed in size only by the orca. They are named "pilot whales" because people once believed that pods were "piloted" by a leader.

There are two living species of pilot whales. The first is the long-finned pilot whale, known scientifically as Globicephala melas. The second is the short-finned pilot whale, or Globicephala macrorhynchus. These two species are very difficult to distinguish when they are swimming in the ocean. To tell them apart, biologists must perform an analysis of their skulls.

The two species live in different parts of the world based on water temperature. Long-finned pilot whales prefer colder waters. They live in two main populations. One group lives in a circumpolar band in the Southern Ocean. This group includes whales off the coasts of Chile, Argentina, South Africa, Australia, and New Zealand. In 2006, this population was estimated at over 200,000 individuals. The second, larger group lives in the North Atlantic Ocean. This group ranges from South Carolina in the United States to the Azores and Morocco. It also reaches as far north as Iceland and Norway. In 1989, this North Atlantic population was estimated at 778,000 individuals.

Short-finned pilot whales prefer tropical and subtropical waters. They are found in the Indian, Atlantic, and Pacific Oceans. They are generally less populous than the long-finned species. For example, about 150,000 are found in the eastern tropical Pacific Ocean. Another group of more than 30,000 lives in the western Pacific near Japan. These whales are often nomadic, meaning they move around. However, some stay in places like Hawaii or California all year.

Pilot whales have very specific physical traits. They are mostly dark grey, brown, or black. They often have light patches, such as a grey saddle patch behind the dorsal fin. They also have an anchor-shaped patch under the chin. Their bodies are robust and feature a large, bulbous melon on the head. This melon is a distinctive part of their anatomy. Their flippers are long and sickle-shaped.

Feeding is an energetic process for these whales. They primarily eat squid, but they also hunt large fish. They might eat Atlantic cod, mackerel, or herring. Most of their dives are shallow, between 30 and 60 meters. However, they are capable of much deeper dives. A long-finned pilot whale was recorded diving over 1,100 meters deep. When hunting fast prey like squid, they often perform fast sprints. This is unusual because many deep-diving animals swim slowly to save oxygen.

Social life is central to the existence of pilot whales. They live in stable groups called pods, usually consisting of 10 to 30 members. Some groups can grow to include 100 or more whales. These pods have close matrilineal relationships, meaning they are based on the female line. Most members stay with their birth pod for their entire lives. Short-finned pilot whales are unique because females undergo menopause. Even after they can no longer have babies, they continue to help their pod.

History shows that other types of pilot whales once lived on Earth. Fossils of an extinct relative, Globicephala baereckeii, were found in Florida. Another extinct dolphin, Globicephala etruriae, was discovered in Italy. Scientists have studied these bones to understand how the genus evolved.

Unfortunately, pilot whales sometimes face serious challenges. They are known to strand themselves on beaches. Marine biologists suggest this might happen because noise pollution damages their inner ear. This ear is used for their principal navigational sonar. Loud noises from military exercises or cargo ships might interfere with their ability to navigate. Despite these issues, the conservation status for both species is currently listed as least concern.