Find Out About Fish and Sea Animals

  • By: The DIG for Kids
  • Time to read: 3 min.
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Fish and sea animals live in a very different environment to ours, and come in all shapes and sizes, from tiny to enormous.

Fun Fish Facts

Fish have been around for about 450 million years or more.

There are almost 27,000 different kinds (species) of fish, and fish are found all over the world, in fresh and salty water

There are more different kinds of fish than any other kinds of animals and birds put together.

Most fish have a swim bladder (a sac filled with air) inside them to keep them afloat – sharks do not, so they have to keep swimming, otherwise they sink.

Some fish have skeletons made of bone (bony fish) and some fish have skeletons made of cartilage (cartilaginous fish), like sharks and rays – people’s noses are made of cartilage.

Fish are cold-blooded.

Someone who studies fish is called an ichthyologist.

Fish do not have lungs, they have gills – as water passes over the gills, which have many blood vessels close to the surface, and the gills absorb oxygen and release waste carbon dioxide.

Some fish are slimy – this mucus protects their skin, makes them move through the water more quickly, and can keep predators (animals and other fish that want to eat them) away.

Cuttlefish can change colour to hide themselves from predators .

Only sharks have eyelids.

The whale shark can grown to 12.2 m long – some gobies are less than 1 cm long.

Fish and seafood is a very healthy food – in Great Britain, people bought more than 387,000 tonnes of fresh, frozen and canned seafood.

There are more than 10,500 fish and chip shops in the UK, selling 276 million portions of fish and chips each year.

About Sea Animals

Whales and dolphins are mammals, not fish.

There are 33 different kinds of seals worldwide, with two living in the UK.

Sea otters can eat up to 9 kg of food a day, and they have the densest fur of any mammals.

A male Northern elephant seal can dive for 20-35 minutes, a harbour seal for 3-7 minutes, a walrus for 10 minutes, a bottlenose dolphin for 8 minutes and a killer whale for 10 minutes.

Marine (sea) mammals can hold their breath for a long time by conserving oxygen – they have more blood and more oxygen-carrying red blood cells than humans, and can slow their heart rate and re-circulate their blood to vital organs, such as the heart, lungs and brain.

The body of a jellyfish is 90-94% water, and a group of jellyfish is called a ‘smack’.

The Lion’s Mane jellyfish has a body up to 2.3 m across and tentacles of up to 36.5 m long.

Male seahorses give birth to live young, and a group of seahorses is called a ‘herd’.

An octopus (plural octopi, octopuses or octopodes) uses a cloud of ink or changes colour to confuse predators and prey.

An octopus has four pairs of two arms, and can grow a new arm if one is injured.

The Romans used a dye made from a tropical sea snail, the ‘spiny dye-murex’, to dye cloth purple – the dye was very expensive and was used for ceremonial robes

Starfish have two stomachs, and most have five arms, with an eye at the end of each arm.

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