Feresa attenuata

The length of the pygmy killer whale is about 2.2-2.4 meters (the longest is 2.6 meters), the newborn body length is about 80 centimeters, and the weight is about 150-180 kilograms (the heaviest is 225 kilograms). It is easy to be confused with other dolphins at sea, especially with melon-headed whales. The pygmy killer whale has a strong body and dark color, especially the forehead. The head is round, without a prominent snout, and the adult has a white lip line. The color of the side of the body is lighter, and the body often has scratches or other bite marks. The abdomen is often white with an anchor-shaped pattern on the chest. The dorsal fin is high and in the middle of the body, slightly sickle-shaped, the pectoral fin is slightly longer and the end is rounded and blunt, and there is a notch in the center of the tail fin. There are 8-11 pairs of upper jaws and 11-13 pairs of lower jaws. The teeth are conical and have a considerable degree of biting and tearing ability. Convention

It is widely distributed and can be found in almost any deep-water tropical or subtropical sea area. It inhabits tropical and subtropical seas around the world and is often found in deeper waters, especially above 500-2000 meters.

The pygmy killer whale is also known as the pygmy killer whale. It is an animal of the genus Pygmy Killer Whale in the family Delphinidae, with no subspecies. The "attentuata" in the scientific name means "wedge" in Latin, referring to the shape of its body gradually becoming thinner from head to tail; and the common name is because its body shape is similar to that of a killer whale, but its body size is much smaller than that of a killer whale.

In 1874, British zoologist John Edward Gray described the species based on two skulls identified in 1827 and 1874 in the British Museum. The next record of discovery was a "rare dolphin" described by whalers in Honshu, Japan in 1952. In 1954, Japanese zoologist Munesato Yamada officially named the pygmy killer whale based on this.

Pygmy killer whales always move in groups, usually with 5-30 individuals per group, and occasionally large groups of more than 100 are observed. Pygmy killer whales swim slowly. According to observations of foreign pygmy killer whales equipped with satellite transmitters, the average speed is about 2.7-3.1 kilometers per hour. In the wild, pygmy killer whales usually interact less with ships and have fewer movements on the water. They can be observed to perform buoyancy, tail fins and pectoral fins slapping water, etc., and are generally less active whales. During the day, it is common to see the entire group floating on the sea surface to rest.

According to the stomach contents of stranded pygmy killer whales, it is known that they mainly eat cephalopods such as fish and squid at night, but there are also records of pygmy killer whales attacking and hunting other small dolphins in the wild, and there are also records of attacking humans. In the rescue of stranded cetaceans, pygmy killer whales are often also a whale species that people need to be particularly cautious of. Little is known about the biology and ecology of pygmy killer whales. Like other cetaceans, they have a long lifespan and mature late. There are records of female whales of about 2 meters reaching sexual maturity and lactating. At present, people have done more research on pygmy killer whales in the Hawaiian waters. Studies have shown that the relationship between pygmy killer whales is quite stable, and the relationship between companions can last for more than ten years.

There are cases of mass stranding of pygmy killer whales around the world, and in the waters of Kaohsiung, Taiwan Province, there were multiple records of groups of pygmy killer whales getting lost in and out of the harbor in February 1995, 2003, and 2005 (some individuals died), but their appearance and health were normal, and other possibilities such as weather, poisoning, and fishing conflicts were ruled out. The main cause of the stranding could not be determined, but underwater noise or unknown interference from other people could not be ruled out. In February 2018, a group of pygmy killer whales got lost again in Kaohsiung Harbor. After several search and rescue units and the Coast Guard worked together to lead them out of the harbor, some still returned. More than a dozen of them died in early March, and two of them had plastic garbage in their stomachs. In April 2019, a live stranding incident occurred in Cijin, Kaohsiung. Six live stranded whales were sent to the Chengda Whale and Dolphin Stranding Rescue Center. After rehabilitation, they died one after another. The cause of the stranding has not yet been confirmed, but CT scans show that most individuals have abnormal unilateral filling in the middle ear bulla, indicating that the pygmy killer whale group has common symptoms, which may affect their hearing or balance, leading to stranding. Within ten days before and after this stranding incident, pygmy killer whales also died and stranded in Kaohsiung, Hualien and Taitung, totaling 13.

Pygmy killer whales are rarely observed and recorded in the wild. The current global estimate is about 40,000, but this number may be underestimated due to the limited area of the survey. For example, the cross-line survey in Hawaiian waters showed that small killer whales only accounted for 1.5% of all whale and dolphin sightings. It is very difficult to estimate the population size and trend of this rare toothed whale. Pygmy killer whales, melon-headed whales and beaked whales are susceptible to large man-made noises (such as military sonar or seismic surveys), and are also affected by small amounts of fishing and bycatch in Asia and the Caribbean.

Listed on the IUCN Red List of Threatened Species: Near Threatened.

Listed on the "List of Nationally Protected Wildlife in China" at Level 2.

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