Animals

1. From the top of the North Pole to the jungles of Borneo, animals have managed to survive pretty much everywhere. Their fascinating eating habits, mating rituals and social structures continue to amaze and enthrall (увлекать) us as there are new things to learn every day about creatures as varied as lions and dung beetles (жуки-навозники), elephants and narwhals (нарва́лы). 

2. Animals are multicellular, eukaryotic organisms. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their lives. All animals are motile, meaning they can move spontaneously and independently, at some point in their lives. All animals are heterotrophs: they must ingest other organisms or their products for sustenance.

3. Biological systems are difficult to predict but even species low down the food chain can get into difficulties when the system is unbalanced. Take Australia, for example; in the Fifties the numbers of rabbits exploded (пережила буйный рост). In similar circumstances this boom can easily be followed by a bust (резкий спад) – through an animal population effectively eating its own food supply. Also in Australia cattle introduction led to such a build-up of cowpats (навозные кучи) that they were destroying the habitat through the build-up of their own waste – until a suitable dung beetle was introduced.HERE See a film about dung beetles 

4. Generally speaking, predator species help provide a balance, keeping animals lower down the food chain in check therefore allowing primary producers (plants) to provide the resources on which the rest of the system depends. Meanwhile, other contributors to the system, such as decomposers, also help the system stay in shape. Without these checks and balances individual species are prone (будут склонны) to boom, bust or potentially to future extinction.