Last Reviewed and Updated on March 7, 2023
Once abundant and recently almost hunted to extinction in many places, the fin whales are a species we can be glad is still around. These gentle giants are a sight to behold, they are one of the largest mammals on the planet, and their bodies are made for speed. Read on and learn some fun facts about the fin whale.
About Fin Whales
Fin whales (Balaenoptera physalus) are a species of baleen whales that are found in all of the world’s oceans. They are also commonly known as finback whales, common rorqual, herring whales,s or razorback whales.
There are at least two subspecies of fin whales.
These whales are very large. They can grow up to be 89.6 feet / 27.3 meters long (largest reported specimen) and weigh around 74 tonnes. Fin whales have long, slender bodies with a sleek appearance that allows them to reach great speed in water (they were nicknamed the “greyhounds of the sea”). They are typically brownish-gray in color with a lighter underside, and they have a distinctive V-shaped head.
Fin whales are filter feeders and primarily eat krill and small schooling fish, such as herring and anchovies, squid, copepods…
They mate in the winter. Fin whales have a gestation period of approximately 11 months. Calves typically nurse for 6 or 7 months before being weaned. They remain with their mother for about a year. Single births are most common, but up to six calves in a single litter have been reported.
The International Union for Conservation of Nature lists fin whales as a vulnerable species. They are a protected species in a lot of their range, and their numbers have been slowly growing in some places, but they are still at risk in many other places.
Interesting Facts About the Fin Whale
From their unique songs to their impressive size, there is much to discover about these magnificent creatures. Explore these facts about the fin whale.
Love learning about animals? Check out our list of 100 animal facts.
1. Fin whales are the second largest animal in the world
It is the second largest whale species, as well as the second largest of all known living animals, both by length and weight. Only the blue whale is larger.
They are also one of the largest animals to have ever existed, surpassing almost all dinosaurs in body length.
2. They can breed with blue whales and produce hybrids
Hybrids between blue whales and fin whales are relatively frequent, which is interesting as the genetic distance between the species is similar to the genetic distance between humans and gorillas. The hybrids are called the fin-blue hybrids and can be, even more interestingly, fertile and survive into adulthood (source).
3. They make one of the lowest-frequency sounds of all animals
Fin whales and blue whales make the lowest-frequency sounds made by any animal. Both are known to produce vocalizations that can reach frequencies as low as 10-20 Hertz (Hz), which is below the threshold of (most) human hearing.
Most sounds they make are pulses from 16 to 40-hertz frequency, with each sound lasting from one to two seconds. They make various sound combinations (songs), combining the short sounds into patterned sequences that can last up to about 15 minutes. They will repeat these sequences in bouts that can last for days.
Although humans don’t necessarily hear their sounds as our ears can’t perceive these frequencies, they are still loud and can be detected hundreds of miles/kilometers from the source.
4. First recorded fin whale sounds confused scientists
US biologists recorded the first fin whale sounds in mid 20th century. The sounds that they picked up were unusually loud and regular, so researchers did not think an animal produced the sound. Before coming to the conclusion fin whales made the sounds, scientists were speculating the sounds were made either by equipment malfunction, some geophysical phenomena or even that sounds were made by Soviet technology for detecting enemy submarines.
5. Fin whales in the Northern hemisphere are smaller than those in the Southern hemisphere
The average size of adults is different in the populations found in the Northern hemisphere than those in the Southern hemisphere.
The average size of adults (males and females) of fin whales in the Northern hemisphere is about 61 and 66 ft / 18.5 and 20 meters, with whales weighing 42.5 and 55.5 tons / 38.5 and 50.5 tonnes on average. Fin whales in the Southern hemisphere are slightly larger, with the average length of adults being between 67 and 72 ft / 20.5 and 22 m and average weight between 58 and 69.5 tons / 52.5 and 63 tonnes.
6. Their newborns are large
Baby whales are massive. As with almost all mammals (platypus and echidna excluded), fin whales give birth to live young. When fin whales are born, they measure about 19.7 to 21.3 ft / 6 to 6.5 m in length and weigh about 4000 lbs / 1800 kg. Talk about a big baby!
They feed on mothers’ milk for about 6 to 7 months before they are weaned.
7. Fin whales are one of the fastest cetaceans
Cetaceans are a group of aquatic mammals that include whales, dolphins, and porpoises.
Fin whales have bodies made for speed! They are the fastest whale and are faster than many dolphins and porpoises. These whales can sustain speeds between 23 to 25 mph / 37 to 41 km/h and can short bursts of higher speeds.
8. When they exhale, the spout can reach heights of 20 ft / 6 m or more
When they surface and exhale the air, the spouts are narrow and vertical and can reach a height of over 20 ft / 6 m in the air.
While they are traveling or resting, they will blow once or twice every minute or so; when they dive for food, they will blow five to seven times in quick succession before diving into the water, with an average dive lasting 6 minutes.
9. Besides humans, killer whales are their only predator
Killer whales are the only known predator of fin whales. While this probably isn’t a killer whale’s first choice of prey, groups of killer whales have been confirmed to attack and kill fin whales on occasion. Even an animal as large as a fin whale isn’t completely safe in the sea.
10. They went from one of the most abundant whale species to almost extinct and slowly back on the rise
Last on our list of facts about the fin whale is how their numbers changed throughout history. Most whales were heavily hunted for their oil, meat, and bones centuries ago, with whaling peaking in the 18th century. Fin whales were spared the horror for most of this time as they were just too fast to catch most of the time. Steam-powered ships and harpoons that exploded on impact turned the tide, and fin whales became a lucrative whale to hunt on an industrial scale. As the ships and hunting techniques further improved, the hunting of fin whales became even easier.
It is estimated that the population of fin whales decreased by over 95% during times of great exploitation in many regions.
In mid 20th century, efforts started to limit or prohibit hunting fin whales in many locations, and the populations are on the slow rise in many places.
They are still threatened by illegal hunting, and many fatalities happen as a result of collisions with ships.