Ask Mr Brain...all will be explained

Why do some bugs give out a bad smell? D WAI Shung Tak Catholic English College Some insects, such as shield bugs, produce a horrible smell if you are silly enough to pick one up. This smell is produced by special glands on the sides of the thorax - the part of an insect's body between the head and abdomen - and helps to deter predators.

While humans are outraged by chemical warfare, insects have been using chemical weapons for millions of years.

Many insects produce foul- smelling chemicals to defend themselves. Others are poisonous.

Some caterpillars store poisons from their food in their bodies to make themselves inedible and bombadier beetles spray their enemies with harmful chemicals. One unpleasant encounter with these insects is usually enough to convince all but the dimmest of predators to stick to hunting tastier and less aggressive prey.

What holds jelly together? Jelly powder contains gelatin which makes food thick and bouncy. Bits of gelatin, so small we cannot see without a microscope, contain many tiny strands, like a braid.

When boiling water dissolves the jelly powder, the gelatin braids are undone, and the strands get mixed in with the water. Then, as the liquid cools, the gelatin pulls back together, trapping the water and sugar in between the strands. This is what holds together this jiggly treat.

Why do sharks swim with their dorsal fin above the surface? The shark's dorsal fin acts as a balancing mechanism - rather like the keel of a boat in reverse. So when it is near the surface of the water, the dorsal fin sometimes sticks out.