Fin Whale
Balaenoptera physalus
The second-largest animal alive — and it's painted differently on each side.
Only the blue whale is bigger. The fin whale is the sleek one: narrow, fast, built like a submarine, and carrying the strangest paint job in the animal kingdom. Its lower jaw is white on the right and dark on the left. Nothing else on Earth is coloured like that.
On the conservation status
Whalers killed around 725,000 fin whales in the Southern Hemisphere alone between 1905 and 1976. Since the hunting stopped the global population has roughly doubled, and in 2018 the IUCN moved them from Endangered to Vulnerable. The United States still lists them as Endangered.
- Length
- Up to 26 m (85 ft)
- Weight
- 36,000–73,000 kg (40–80 tons)
- Lifespan
- 80–90 years
- Diet
- Krill, small schooling fish, squid
- Dive depth
- Usually under 250 m
- Range
- Every ocean, mostly deep offshore water
The good stuff.
The left and right sides don't match
The right lower jaw is bright white; the left is dark. Even the baleen inside follows the rule — pale on the right, dark on the left. No other animal is known to be asymmetrically coloured like this.
And the asymmetry has a job
Fin whales tend to roll onto their right side when they lunge into a shoal. The best guess is that the white jaw flashes below the fish and panics them into a tighter ball — easier to swallow in one gulp.
The greyhound of the sea
That nickname is over a century old and completely earned. A fin whale can cruise at around 37 km/h and burst faster. Early whalers mostly couldn't catch them at all. That only changed in the 1860s, when steam-powered whaling began.
Their voice is used to X-ray the seafloor
Fin whale calls are 20 Hz pulses at up to 186 decibels, among the loudest sounds any animal makes. In 2021 scientists used recordings of them as a seismic source to map the layers of rock under the ocean floor.
They swallow more than their own body
The pleated throat balloons out until the whale takes in a volume of water larger than the whale itself, then squeezes it back through the baleen and keeps whatever couldn't fit through.
Everyone wears a different chevron
Behind the head is a pale V-shaped marking. Like a humpback's tail or an orca's saddle, no two are quite alike, so researchers use it to recognise individuals year after year.
Wait, really?
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A fin whale's blow is a tall narrow column up to 6 m high — often the first thing you see.
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The dorsal fin sits about two-thirds of the way down the back and hooks sharply backwards, which is how you tell one from a blue whale at sea.
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Fin whales and blue whales sometimes have calves together — one of the very few wild whale hybrids we know of.
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Their calls are so low-pitched that for years some recordings were filed away as unexplained geological noise.
What it sounds like
You're hearing an Atlantic fin whale call. Sped up 10× — at real speed it sits right at the bottom edge of human hearing.
Enormously loud, enormously slow 20 Hz pulses, repeated in patterns for hours. Right at the bottom edge of human hearing — more felt than heard.
Recording: NOAA Pacific Marine Environmental Laboratory · Public domain · Source
Where you might see one
The Gulf of St Lawrence and the Bay of Fundy, the Mediterranean's Pelagos Sanctuary, Iceland in summer, and the Sea of Cortez year-round.
The trouble
- Ship strikes, especially in busy shipping lanes
- Entanglement in fishing gear
- Ocean noise drowning out calls they use to find each other across whole ocean basins
- Whaling that still continues in a small number of places
One real thing
Fin whales are one of the large whales most often reported hit by ships. Support rerouting and slow-down zones in shipping lanes that cross their feeding grounds.
More ways to help