Balaenoptera physalus

The maximum weight of the fin whale is 110 tons. The eyes are small and located at the upper and rear corners of the mouth. There are two blowholes. There are 50 to 100 gray-brown sensory hairs around the upper and lower jaws and the blowholes. The back is blue-gray and the belly is white. There is a dorsal fin at the back of the body, small pectoral fins with pointed ends, and a wide caudal fin. There are 50 to 60 folds on the throat and chest, and up to 114 folds, which reach the navel. The mouth is large, with about 260 to 470 baleen plates on each side of the mouth, and an average of 350 to 360. The colors are different. The front 1/2 on the right side is light yellow, and the rest are gray-black. Many of the horny plates are partially or completely white, sometimes slightly yellow. There is a pair of breasts. The left side is dark gray. There are 260 to 480 baleen plates on each side, and the front 20 to 30% of the baleen on the right side is white or yellow, and the rest is dark

Fin whales have a wide range. They can be found in all major oceans of the world, from polar regions to tropical waters. Fin whales avoid only ice-filled waters near the North and South Poles and relatively small seas such as the Red Sea, the Persian Gulf, the eastern Mediterranean, and the Baltic Sea. Fin whale densities are highest in warm and cold waters; they rarely congregate in hot equatorial waters, and prefer waters deeper than the continental shelf to shallow waters.

Fin whales are one of the fastest whales, with a speed of up to 37 kilometers per hour, and a record high of 40 kilometers per hour. They are known as the "greyhound of the deep sea".

Fin whales use their baleen to filter food and then swallow it. Their food includes small fish, squid and crustaceans (including mysid shrimp and krill). When feeding, they move at a high speed of 11 kilometers per hour, then open their mouths and suck up up to 70 cubic meters of seawater each time. After sucking in the seawater, they close their mouths and spit the seawater out through their baleen. The seawater passes through the baleen and returns to the sea. Small fish, crustaceans and other food will be separated and become the food of the fin whale. An adult fin whale has 262 to 473 baleen plates on each side of its mouth. The baleen plates are made of keratin, which has been worn away for a long time and turned into some hair-like things called baleen. These baleen can be up to 76 cm long and about 30 cm wide. Fin whales often dive to depths of more than 200 meters, using their four lungs to allow them to stay in the water longer to hunt krill. Each time they open their mouths, they can suck up about 10 kg of krill. A fin whale can eat 1,800 kilograms of food every day. Scientists have calculated from this data that they spend three hours a day eating to replenish the energy they have consumed. If the number of prey is insufficient or the prey is too deep, the fin whale will have to spend more time looking for prey. According to scientists' research, fin whales will circle around their prey at high speed, causing the prey to gather into a ball shape with extremely high density. At this time, the fin whale will filter out the prey one mouthful at a time and swallow it into its stomach.

When fin whales float to the surface of the sea, people first see the blowhole, followed by the dorsal fin. The blowhole is vertical and narrow, and the air and liquid ejected can reach a height of 6 meters. Every time they float to the surface, they will blow several times, staying on the surface for 1 and a half minutes each time. During the period of floating to the surface, their tails will still remain submerged in water. After that, they will dive to a depth of 250 meters and stay in the water for 10 to 15 minutes each time. Fin whales, like many other whales, frequently breach the surface of the ocean, and are able to hold their entire bodies in the air for the duration of the breach.

When American researchers first recorded the calls of fin whales, they had no idea what whales were making these unusually loud, long, pure, regular sounds. They first suspected that the sounds were caused by mechanical failure, a geophysical phenomenon, or even Soviet detection of enemy submarines. Eventually biologists determined that the calls were made by fin whales. Like other whales, male fin whales have long, loud, low-frequency calls. As far as humans know, blue whales and fin whales have the lowest calls of any animal in the world. Most of the fin whales' calls are low-pitched, ranging from 16 to 40 Hz (most humans can hear between 20 Hz and 20,000 Hz), each lasting one to two seconds, and composed of many different calls in a sequence lasting 7 to 15 minutes. Fin whales make these calls repeatedly over many days. These sounds reach 184-186 decibels at a reference distance of one meter and one atmosphere, and can be detected thousands of kilometers away. Because this sound is made during the whale's breeding season, scientists believe that this is likely a courtship display. Over the past 100 years, ocean noise caused by ships and military activities may have slowed the recovery of fin whales because these sounds may prevent male and female whales from contacting each other.

Fin whales enter sexual maturity at the age of 2 to 12 years, and female whales give birth every 2 to 3 years. Generally speaking, female whales only give birth to one calf at a time. According to relevant records, the world's largest birth is six. Female whales mate during the winter and need to be in temperate and low-latitude waters. Their gestation period is about 11 months to a year. Newborn whales will be weaned 6 to 7 months after birth and 11 to 12 meters long. After that, the calf will follow its mother to the winter feeding area. There are also records of hybridization between fin whales and blue whales.

The International Whaling Commission banned the hunting of fin whales in the Southern Hemisphere in 1976. According to records, about 46,000 fin whales were hunted in the North Pacific between 1947 and 1987. However, this number is incomplete because the Soviet Union determined that these whales were illegally killed. Fin whales in the North Pacific were fully protected by the IWC in 1976, and whaling in the North Atlantic was banned in 1987, except for some aboriginal and research whaling. Aboriginal whaling continues in Greenland in the Northern Hemisphere under IWC procedures. The meat and other products of the whales are widely circulated in the Greenlandic market, but export is illegal. In the absence of uncertainty about the number of fin whales, the IWC has given Greenland an annual quota of 19 whales. Iceland and Norway are not subject to the IWC's moratorium on commercial whaling, as they oppose the ban. In October 2006, Iceland's fisheries department authorized whalers to kill nine fin whales by August 2007. Japan has targeted fin whales for research in the Southern Hemisphere, with a special sanctioned study that calls for 10 whales to be killed each year in 2005-2006 and 2006-2007. In 2007-2008 and the next 12 seasons, 50 fin whales will be killed each year.

Listed in the Convention on International Trade in Endangered Species of Wild Fauna and Flora: CITES - Level Ⅰ.

Listed in the IUCN Red List of Threatened Species: IUCN RL - Vulnerable.

Listed in the China Key List - Level Ⅱ.

Listed in the China Biodiversity Red List - Vertebrate Volume, with an assessment level of endangered (EN).

CITESI, approved as a Class 2 protected aquatic wildlife (including artificial populations) in China on October 9, 2018.

In February 2021, it was included in the Class 1 List of China's National Key Protected Wildlife.

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