Ray Mullet's expert analysis

The stonefish is a truly amazing fish. It simply sits around rocks on coral reefs, waits for a tasty fish or shrimp to pass, then gulps it down in just 0.015 seconds. Disguised as a greenish-brown piece of seaweed-covered coral, the stonefish gives its prey no chance.

However, most humans are also given little chance, which is unfortunate as the stonefish is the most poisonous fish in the world. Along its back lie 13 needle-like spines that release venom if pressed. This is probably a defence against large bottom-feeding fish that might attack the stonefish, although the spines will still sting when an unsuspecting bather stands on the fish. The spines are so strong that they will even pierce your shoe. The poison is extremely painful, causing the body to go numb, and often leading to death by heart failure. Australian aboriginals even have a dance to teach children to beware of the stonefish.

Two different species of stonefish live on coral reefs in northern Australia and the Indo-Pacific coast. Stonefish live in shallow water but can survive out of water for short periods if necessary, eg if they are stranded by the falling tide. They grow to 35cm (14") in length.

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Stonefish
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© Below Water

Leafy Sea Dragon
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© Below Water

The second placed fish in our camouflage competition is the beautiful relative of the seahorse, the Leafy Sea Dragon. The Sea Dragon has several useful adaptations that help it blend into the background:

• Sea dragons can change their colour to blend into any background depending on their diet, location or even stress levels
• The sea dragon has lobes of skin growing on its body and fins that look like pieces of seaweed
• The sea dragon barely seems to move, using tiny translucent fins on its back and on the side of its head to swim. It seems to float like a piece of seaweed - you would never notice it was there.

As with seahorses, the male sea dragon has a special pouch in which he carries and gives birth to the young. Both species also feed on a diet of shrimp and small fish.

Recent research (Connolly, 1998) has shown that leafy sea dragons travel hundreds of metres from their home and then return to exactly the same spot, using a well-developed navigation system. It had previously been thought that they barely travelled at all.

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You may have seen mackerel for sale in food shops and noticed their shiny white underside and mottled backs. It is this colouring - known as countershading - that provides the mackerel with protection from predators. If the mackerel is seen from below its white underside looks like the light from the surface of the water. If viewed from above the greyish black speckles and stripes blend in with the ripples on the water and the darkness below.

The mackerel is a member of the same family as the tuna. The examples in shops are quite small as mackerel in the wild usually grow to 40 cm (16") but can reach 66cm (26") in length. They are found in large shoals in the north and west Atlantic Ocean and Mediterranean Sea.

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Mackerel
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Shrimpfish
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© Andy Foden



Shrimpfish shoal
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© Andy Foden

Shrimpfish grow to 15cm (6") and have their own bony armour, which is just as well as they like to hide from predators, head first among the prickly points of the black spiny sea urchin. The fish has a black stripe down its body that helps it blend in with the lines of the urchin's black spines.

Unlike most fish which swim horizontally, the shrimp fish always swims and eats with its head down - in the direction of the sea urchins spines. They eat tiny shrimps, just like their relatives the sea horse and sea dragon. The shrimpfish also has the seahorse's tube-like snout and small, toothless mouth.

The body of the shrimpfish is long and transparent, and is protected with hard, scale-like extensions of its vertebral column (spine) that form a jagged edge. Adult shrimpfish have a long spine that extends from their body - this is actually an adapted dorsal spine.

Shrimpfish live in shoals, throughout the Red Sea, Indian Ocean and Pacific Ocean.

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