Ask Mr Brain . . . all will be explained

PUBLISHED : Wednesday, 21 June, 2000, 12:00am
UPDATED : Wednesday, 21 June, 2000, 12:00am

Were dinosaurs cold-blooded or warm-blooded? This is a question that puzzles a lot of scientists. Warm-blooded is another term for endothermic, which means the animal is able to keep a fairly even body temperature without having to worry about the weather.

Mammals, including humans, and birds are the endothermic animals alive today.

Cold-blooded, or exothermic, means the animal does not produce heat inside its body. It has to sit in the sun to warm up or sit in the shade to cool down - the weather is very important to exothermic animals. Reptiles are the exothermic animals still alive today.

Endothermic animals produce body heat, which means they have to eat more food and can move quickly at any time of the day.

Exothermic animals do not need as much food since they do not produce body heat, which also means they can be very sluggish on a cold day.

A big animal like a dinosaur would require a lot of food to live. Even if it were exothermic, it would still require a lot of food. Some dinosaurs are huge but have very small mouths and it is a mystery as to how they ate enough to stay alive.

If dinosaurs were endothermic, they would need even more food, which is even more puzzling. Some dinosaurs seemed to live in cold environments.

It would take a long time to heat up a big body by lying in the sun. How could they have lived if they were that sluggish? There are a lot of fossil clues that can be used to argue one way or another, but scientists are still trying to find out the answer.

Why are ladybirds called ladybirds? The name comes from the idea that these beetles are somehow dedicated to the Virgin Mary, as in Our Lady's beetles. They are called by similar names in many European countries, like Nyckelpiga (Our Lady's Key-Maid) in Sandinavia, Jungfrau Marias Gullhona (the Virgin Mary's golden hen) in Germany and Betes de la Vierge (animals of the Virgin) in France. In England, they were also called ladybird, or Bishop Barnabee. For some reason, the name ladybird beetle stuck.

Why is it that we float in water but fish do not? It has to do with body tissue. Fat floats, and humans have comparatively more fat than a fish.

Some fish also have a 'swim bladder', like a balloon in their belly. When they want to float, they fill it with gas, and when they want to sink, they let it shrivel up.

What makes flowers bloom at night? Flowers bloom at night because they are pollinated by nocturnal insects, such as moths, or nocturnal animals, such as bats.

This is an example of co-evolution between a plant and its pollinator.