165 facts
you can use
at dinner.

A big male's dorsal fin can stand 1.8 m tall — taller than most adults.

A blue whale's blow shoots 9 metres into the air — you can spot it from kilometres away.

The bumps on a humpback's head are called tubercles, and each one grows a single hair used to sense the water.

Ambergris — a rare, waxy substance from a sperm whale's gut — was once worth more than gold to perfume makers.

Narwhals can hold their breath for around 25 minutes under solid ice.

Beluga comes from the Russian word for white.

One gray whale was tracked swimming from Russia to Mexico and back — nearly 23,000 km, the longest migration ever recorded for a mammal.

A fin whale's blow is a tall narrow column up to 6 m high — often the first thing you see.

A bowhead eats about 100 tonnes of tiny crustaceans a year.

Scientists only described the vaquita in 1958, from skulls found on a beach.

The bottle nose is its short, thick beak. The round bump behind it is the melon, full of fat, which helps focus the clicks it hunts with.

Males are about 16% longer than females and weigh about 55% more, which makes botos one of the whale and dolphin kinds where males and females differ most in size.

They can hold their breath for around 30 minutes.

They can move surprisingly fast on ice — fast enough that Antarctic researchers keep their distance.

They carry scientific instruments: tagged elephant seals have collected huge amounts of the ocean temperature data we have from under Antarctic ice.

They've been around, largely unchanged, for roughly 15 million years — sometimes called living fossils.

They can sleep floating at the surface with one flipper in the air — that flipper is a heat exchanger, warming or cooling the blood.

Pups are born nearly a metre long and 20 kg — about twice as heavy as a newborn harbor seal.

Their blubber can be 15 cm thick — enough to survive water just above freezing.

There are 20 separate groups of polar bears, spread across Canada, the United States, Greenland, Norway and Russia.

They're the smallest marine mammal and the heaviest member of the weasel family.

A manatee's flipper has fingernails — a leftover from its land-mammal ancestors.

Dugongs sing to each other with chirps, whistles and barks that carry through the water.

Its mouth is about a metre wide, and it sits right at the front of the head rather than underneath like most sharks.

Pups are born 1.1–1.6 metres long — already bigger than some kinds of adult shark.

Newborn tiger sharks are 51–76 cm long — about as long as your arm.

A population of bull sharks lives in Lake Nicaragua, and swims between the lake and the Caribbean along the San Juan River.

In Australia, fishers call sawsharks saw dogs, or doggies.

Largetooth sawfish have been found in rivers 1,340 km from the sea.

Its back is mauve-grey, with a dark collar across the back of its head.

Its stomach has been found holding up to 50 or more stingray spines. Stingrays are on the menu.

Whether a hatchling turns out male or female depends on how warm the sand is — warmer nests make more females.

There are around 28% more nesting green turtles now than in the 1970s.

The leatherback is found in more places than any other reptile, in the Atlantic, Pacific and Indian oceans.

There are 18 species of penguin, and the emperor is the biggest.

Their weight swings through the year: 10–15 kg at the start of breeding, down to 8–11 kg by the end.

It's the third-largest penguin alive.

On the ice they walk at about 2.5 km/h — about half a person's walking speed.

The South Orkney Islands have about 927,000 more breeding pairs.

Chicks are ready to go to sea at 60 to 70 days old.

The males come back to the colony first, and the females arrive about a week later.

Penguins only started nesting at Boulders Beach, near Cape Town, in the 1980s.

Kororā is their Māori name, and they used to be called little blue penguins.

About half of all blue-footed boobies breed in the Galápagos Islands.

Pelicans often fly in a line just above the waves, gliding on the air pushed up by the water.

Sailors called it the man-o'-war bird, after the warships of their day, for the way it attacks other birds.

Puffins return to the same colony year after year, and often to the same mate and the same burrow.

It was named "wandering" for the huge distances it travels over the ocean.

Tuna have to keep swimming to breathe: moving forward is what pushes water over their gills.

It makes up about 80% of the octopus caught around the Yucatán Peninsula.

Its scientific name, verrucosa, means covered in warts.

In Washington State, it's against the rules to take an octopus at eight popular dive sites in Puget Sound, so divers can visit the same animals again and again.

The grey saddle patch behind the fin is as unique as a fingerprint, so researchers use it to name every individual.

Their earwax builds up in layers like tree rings, and scientists read it to work out a whale's age and stress.

A breaching humpback throws its whole body clear of the water. Nobody is completely sure whether it's communication, parasite removal, or just fun.

Moby Dick was based on a real white sperm whale, Mocha Dick, and on the sinking of the whaleship Essex in 1820.

Their skin, called muktuk, is an important traditional Inuit food and is unusually rich in vitamin C.

One captive beluga, NOC, spontaneously altered his calls to imitate human speech patterns closely enough that a diver climbed out of the water thinking someone had shouted at him.

They have no dorsal fin, just a low hump followed by a row of bumps called knuckles.

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.

Its white chin is dotted with black spots, like a necklace.

There are just seven kinds of porpoise in the world, and the vaquita is the smallest.

Nicklo, the oldest wild dolphin ever known, lived in Sarasota Bay in Florida and was last seen in 2017, aged 67.

Scientists still argue about whether there is one kind of boto or three: the Amazon, Bolivian and Araguaian river dolphins. For now the main scientific list counts them as one.

A resting harbor seal's heart slows so much that its body can send nearly all its oxygen to the brain and heart alone.

Hydrurga leptonyx means water worker with a slender claw.

Their blood holds so much oxygen that they can shut down blood flow to most of the body while diving.

Monk seals moult their entire coat and the top layer of skin once a year, all at once.

Sea lions can be taught abstract logic tasks that most animals fail.

They sometimes eat northern fur seal pups and harbor seals, which is unusual for a sea lion.

Males inflate air sacs in their necks to make a deep bell-like gonging sound underwater during breeding season, and can use those sacs as a built-in flotation pillow while they sleep in the water.

Its coat can look white or yellowish. It's water-repellent hair on top of a thick, dense undercoat.

A raft can be a couple of otters or, in Alaska, over a thousand.

They have only six neck vertebrae instead of the usual seven, so they turn their whole body to look around.

A newborn calf is already about 1.2 m (4 ft) long.

In the Philippines it's called butanding; in Mexico, pez dama — the domino fish, for the spots.

Researchers tell great whites apart by the jagged back edge of the dorsal fin, which is as individual as a fingerprint.

Off Hawaii's remote islands, tiger sharks turn up every summer just as young albatrosses make their first flights, and catch the ones that land on the water.

Every winter, big female bull sharks gather off Playa del Carmen in Mexico.

There are about ten kinds of sawshark. One of them, the sixgill sawshark from southern Africa, has six gill slits on each side instead of five.

International trade in sawfish, saws included, has been banned since 2007.

It feeds by filtering tiny shrimp called mysids out of the water with plates in its gills.

From above it's brownish-grey to olive, and underneath it's pale. A fish looking up sees a pale belly against the bright surface; one looking down sees a dark back against the deep.

Hawksbill embryos and hatchlings have been recorded making faint sounds in and around the nest.

In Hawaii, green turtles haul themselves up onto beaches just to rest in the sun, which few sea turtles do.

Leatherbacks have been tracked chasing jellyfish in water close to freezing, then warming up near the surface.

Winter blizzards around their colonies can blow at up to 200 km/h.

There are two subspecies, and a small colony on the Falkland Islands is still growing.

Sea lions hunt them at sea. On land, skuas and striated caracaras go after their eggs and small chicks.

A parent brings back 300–650 g of food per meal, depending on how big the chicks are.

Males are a little bigger than females.

No more than 1,000 live on the Falkland Islands.

It's the smallest of the crested penguins.

Collecting their eggs used to be a big reason they declined. It's illegal now.

A grown-up little penguin weighs about as much as a bag of sugar.

They don't build real nests. Eggs are laid on bare ground, and the parents keep them warm with their feet.

It's the national bird of Barbados, Saint Kitts and Nevis, and the Turks and Caicos Islands.

Males are all black except for the red pouch. Females have a white chest.

In the 1970s, scientists in Maine moved young puffins to Eastern Egg Rock and put out wooden puffin decoys. The island now has nesting puffins again.

To court, a pair spread their wings, wave their heads and clack their bills together while braying.

It's the biggest of all the tunas.

Fishers there use a traditional method called gareteo: drifting boats trail lines from bamboo poles, baited with crabs and no hooks. The octopus grabs the crab and holds on while it's lifted aboard.

Cabo Pulmo's reef is thought to be about 20,000 years old.

A different octopus, a deep-sea species named Graneledone boreopacifica, holds the record for guarding eggs: over four and a half years. A giant Pacific mother stays about six months.

Orcas are the second most widely distributed mammal on the planet. First place: us.

Roughly 10,000–25,000 blue whales are left, down from perhaps 350,000 before whaling.

Their song only travels in the low frequencies — but it can carry across an entire ocean basin.

Their heart rate drops to a handful of beats per minute on a deep dive to save oxygen.

Monodon monoceros means one tooth, one horn.

They can swim in water only slightly deeper than their own body.

Baby gray whales drink around 190 litres of milk a day.

Fin whales and blue whales sometimes have calves together — one of the very few wild whale hybrids we know of.

Arctic peoples have hunted bowheads for thousands of years, and still take a small number each year under strict limits.

Vaquitas are shy and keep away from boats, which is part of why they're so hard to count.

Scientists in Sarasota Bay have followed the same dolphin families since 1970 — the longest study of wild dolphins anywhere.

In Amazon folklore, botos are magical creatures that can turn into people.

Their eyes have a reflective layer behind the retina, like a cat's, for seeing in dark water.

Only orcas hunt adult leopard seals.

A bull's chest shield — thick, scarred, wrinkled skin — is armour built for fighting.

Pups are born black and lose that coat within their first few weeks.

Their whiskers, like a seal's, can track a fish through murky water.

A rookery is for breeding; a haul-out is just for resting. Sea lions use both, for different things.

A walrus can slow its heart rate right down to survive long, cold dives.

It's the largest bear species alive.

Some sea otters specialise: one individual will eat mostly crabs while its neighbour eats mostly clams, and mothers teach the preference to their pups.

Steller's sea cow, a 9-metre Arctic relative, was hunted to extinction within 27 years of Europeans finding it.

It is the only plant-eating mammal that lives entirely in the sea.

At most of the famous feeding spots, nearly every whale shark is a young male. Where the grown-up females spend their time is still mostly a mystery.

Isla Guadalupe, off Mexico's Pacific coast, is one of the best places in the world to study great whites.

When a dead whale floats at the surface, dozens of tiger sharks can gather to feed on it.

They've been found in the Ganges and Brahmaputra rivers in India, and in the Zambezi in Africa.

It lives on sandy and gravelly sea floors, mostly deeper than divers go.

Young sawfish are sometimes eaten by crocodiles and big sharks.

Pups are born in spring and early summer, between April and June.

It lives in warm seas all over the world, from the coasts of Brazil and Australia to Hawaii and Japan.

Mexico's Yucatán Peninsula has some of the most important hawksbill nesting beaches in the Atlantic.

A hatchling is about 5 cm long, small enough to sit in your palm.

In 2012, scientists listened to leatherback nests on Barra de la Cruz beach in Oaxaca, Mexico, and recorded sounds coming from the eggs and hatchlings.

A chick hatches weighing just 150–200 g, and needs about 42 kg of food from each parent to grow up.

Helicopters flying low over a colony can make some pairs fail to breed, or move somewhere else.

In 2002 a harmful algal bloom poisoned many gentoos, and it took the population several years to recover.

They breed in 190 to 250 colonies around Antarctica.

Small populations live as far away as Bouvet Island and the Balleny Islands.

Their golden crest is what gave them the name macaroni.

Sea lions hunt them at sea, and skuas and caracaras take eggs and chicks at the colonies.

In Namibia, the most important colony, Mercury Island, had more than 2,500 pairs in 2015 and none at all in 2023.

They lay one or two eggs, which take up to 36 days to hatch.

Females look as if they have bigger pupils than males, because of a dark ring around each one.

In Mexico it's called pelícano pardo.

In the 1980s, about 20,000 pairs nested on Isla Santa Margarita in Bahía Magdalena, one of the biggest colonies of its kind ever counted.

They're sometimes nicknamed the clown of the sea and the sea parrot.

The wandering albatross used to be counted as a group of subspecies. Scientists have since split off several of them as their own species, including the Antipodean, Tristan and Amsterdam albatrosses.

A bluefin can dive 1,000 m down and come back up, swapping warm surface water for the cold and dark below.

Its saliva holds a toxin that stops a crab moving while the octopus eats it.

Coral reefs cover a tiny part of the sea floor, but about a quarter of all the kinds of animals in the ocean live on them.

Sea otters, harbor seals and Pacific sleeper sharks all hunt it.

No wild orca has ever been recorded killing a human.

Their calls are so low-pitched that for years some recordings were filed away as unexplained geological noise.

Dolphins swallow fish whole and head first, so the spines don't catch in their throats.

Botos are known by other names too: bufeo, tonina, and in Spanish, delfín rosado, the pink dolphin.

Whale sharks gather in the hundreds off Mexico's Yucatán every summer for a plankton feast called the afuera.

Cocos Island, the Galápagos Islands and Malpelo Island form a triangle in the eastern Pacific. Hammerheads travel between them.

A leatherback hatchling is only about 6–7 cm long, and a grown one can weigh over 700 pounds.

An adult eats 2–3 kg of food a day, and up to 6 kg when it's fattening up to breed or moult.

Scientists only described it in 1966, from octopuses brought in by fishers in Campeche.