How long do horses live, and how much dung does an elephant produce?

We explore the curious questions that science can answer

It’s very rare for horses to live more than 60 years (Getty/iStock)

What is the average lifespan of a horse?

According to the Science and Technology Desk Reference book, the maximum lifespan of a horse is 62 years. Obviously not all horses will live this long and an average value will be somewhat less than 62 years. The lifespan of a horse will depend on, amongst other things, the conditions in which it lives and the pressures that are put on it during its life.

Do animals get addicted to substances?

Yes. It seems animals, like humans, can get addicted to substances that are of no biological value. Rats, trained to inject themselves with cocaine, continue to do so even after they start having extreme reactions like seizures.

We cannot assume that rats become addicted for the same reasons as humans, or by the same mechanisms, although similarities in brain structure suggest common “addictive” pathways.

A good example of a useful addiction in nature is the koala bear’s love of eucalyptus leaves. Koalas will die without them. This addiction is acquired, rather than chosen, as the koala cub gets used to the eucalyptus in “its mother’s milk. But there are also benefits. Eucalyptus leaves contain precious water. They also contain aromatic oils which help to keep the bears’ fur free of parasites, relax their muscles and lower their blood pressure. Other animals eat plants, fruits and berries (for example, opium poppies and rotting fruits) which contain intoxicating substances. 

How many species of shark are there?

There are approximately 350 different species.

Why is it that dogs see only in black and white?

In fact, they don’t; they have colour vision, but it is similar to that of red/green colour-blind people. In human beings, the retina at the back of the eye has three types of “cone” (colour-sensing cells) – blue, green and yellow (often known as “red”). Dogs have only the blue and yellow ones, which means in practice that they are unable to detect the difference between red and green, although they can distinguish between yellow and blue. It is thought that only animals such as birds and primates, which need colour “vision in order to distinguish between ripe and unripe fruit, need colour vision.

However, dogs are highly sensitive to changes in movement because their eyes have a greater than usual number of “rods” – important for black-and-white vision – which contributes to their hunting ability.

How deep can a sperm whale dive?

They are known to dive to 350m (1,150 feet) but the deepest was found tangled in cables 1,134m (3,720 feet) down.

Do fish hear?

Yes! Carp, particularly goldfish, are considered to be hearing experts. They have three bones, the Weberian ossicles, connected to the swim bladder and vibrations are transported to the brain. Some fish also sing. In California some people living in houseboats heard a buzzing at certain times of the year. Rumour put it down to aliens but it was eventually found to be the noise a Micharen male fish makes to attract the females.

How much dung does an elephant produce?

About 150kg of dung a day – about 24 stone, or one tonne of dung a week.