Blue whale
Balaenoptera musculus
- Size
- Up to 30m long: the biggest animal ever
- Look for it
- All year round
- Where
- Every ocean except the high Arctic
A vast, long, blue-grey whale, mottled with paler patches, with a tiny fin far down its back.
The dolphin that follows you
This page is the open ocean, far from land. Move your pointer across the water and your animal will swim after you. Choose a different animal at the bottom, and tap the notes to open them.
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01 · NamesNames of their own
Each dolphin has its own whistle, and others use it to call that dolphin, like a name.
02 · SleepHalf asleep
A dolphin rests one half of its brain at a time, so it can keep swimming and breathing.
03 · SoundSeeing with sound
It sends out clicks and listens to the echoes, to find fish it cannot see.
04 · TeamWorking together
Dolphins herd fish into a tight ball, or onto a mud bank, and take turns to feed.
05 · PlaySurfers
Dolphins ride the waves in front of ships and surf breakers near the shore, apparently for fun.
06 · BritainBritish dolphins
The bottlenose dolphins of the Moray Firth in Scotland are the biggest in the world, to cope with the cold.
Meet them all
Who's who in the open ocean
Bottlenose dolphin
Tursiops truncatus
- Size
- About 2.5 to 4m long
- Look for it
- All year round
- Where
- Warm and cool seas all round the world, including Britain's
A sleek grey dolphin with a short beak, a curved fin on its back and what looks like a smile.
Great white shark
Carcharodon carcharias
- Size
- Up to 6m long
- Look for it
- All year round
- Where
- Cool coastal seas, especially off South Africa, Australia and California
A big, powerful shark, grey above and white below, with a pointed snout and a tall fin on its back.
Green sea turtle
Chelonia mydas
- Size
- Shell up to 1.2m long
- Look for it
- All year round
- Where
- Warm seas all round the world
A big turtle with a smooth, heart-shaped shell and long front flippers that work like wings.
Giant manta ray
Mobula birostris
- Size
- Up to 7m across
- Look for it
- All year round
- Where
- Warm seas all round the world
A huge, flat, diamond-shaped fish that flies through the water on wide wings, with two horn-like fins at the front.
Sailfish
Istiophorus platypterus
- Size
- Up to 3m long
- Look for it
- All year round
- Where
- Warm waters of the Atlantic, Indian and Pacific oceans
A slim, steel-blue fish with a long, pointed bill and a huge sail of a fin down its back.
Through the year
When to look for them
Ocean animals travel with the seasons, but every one of these is somewhere in the world's seas all year. The animal following you is shown in red.
Blue whale
Dolphin
Great white shark
Sea turtle
Manta ray
Sailfish
Good to know
Six things about the open ocean
The blue planet
The oceans cover 71 per cent of the Earth and hold 97 per cent of all its water.
Half our oxygen
Tiny drifting plants in the sea make about half the oxygen we breathe.
Why the sea is blue
Water soaks up red light and scatters blue, so deep, clear water looks blue.
Dark on top, pale below
Many ocean animals have dark backs and pale bellies, so they are hard to see from above or below.
Ocean highways
Whales, turtles and sharks cross whole oceans each year along routes we are only starting to map.
The plastic problem
Millions of tonnes of plastic reach the sea every year. Turtles mistake bags for jellyfish.
Photo gallery
Real photos of the animals on this page. Tap one to see it bigger.
Blue whale
Bottlenose dolphin
Great white shark
Green sea turtle
Giant manta ray
Sailfish
Photos are from Wikimedia Commons and are used under free licences. They have been resized, and cropped where they appear in link previews. Open a photo to see who took it.
Most of the planet
Seas cover nearly three-quarters of the Earth, and most of that is open water with no land in sight. The animals that live there are built for one thing above all: distance.
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