Fish were the first animals with backbones to appear
on Earth, more than 500 million years ago. They have
since evolved into a wonderful variety of forms. From
powerful sharks to delicate seahorses, fish now make
up more than half of all vertebrate species. Most fish
live in the salty oceans, like those shown below, but
many – including the fish on the opposite page – live
in freshwater lakes and rivers. A few, such as salmon,
are able to live in both.Fish
(^3) FORCEPS FISH
A type of butterflyfish that lives on the
coral reefs of the Indian and Pacific
oceans, the forceps fish has a highly
elongated snout with a very small
mouth at the tip. The fish uses
this to pick tiny animals from
coral crevices, and from the
spines of sea urchins.
(^4) SEAHORSE
These strange fish owe their name
to their horse-like heads. They live
in shallow seas, where they cling to
marine plants with their tails. The
male “incubates” the female’s eggs
in a pouch on his belly.
Prickly pufferfish are also
called porcupinefish
Clinging to weed with its tail helps
a seahorse resist strong currents
fin distracts enemies Black “eyespot” on
from the fish’s head
Boxfish eat
tiny animals
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(^1) RAY
Closely related to sharks, with
skeletons made of cartilage, rays
are flattened fish that swim by
using their pectoral (side) fins like
wings. They live on the seabed,
hunting smaller fish and shellfish.
(^2) BOXFISH
The curious boxfish are named for
their box-like defensive armour,
formed from thick, fused scales.
This prevents all body movement,
so the fish swim by using their
small fins like oars.
Its flat shape and
excellent camouflage
make this ray hard to
spot on the seabed
A ray’s nostrils and mouth
are on its underside. Eyes
sit on top of the head
(^5) PUFFERFISH
Pufferfish defend
themselves by inflating
their bodies with water
so they are hard for predators
to swallow. Some species have
sharp spines that add to the
effect, and many of their internal
organs contain lethal poisons.
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