Biology Adaptation and Survival

Organisms need a supply of materials from their surroundings or other organisms to allow them to survive and reproduce.

Living organisms have different requirements to survive:

Plants - O2, CO2, H20, light and nutrients from the soil to produce glucose energy.                     Animals - Food from other organisms, water and oxygen.                                                           Microorganisms - Some similar to plants, others to animals. Some don't need oxygen or light.

Organisms that survive and reproduce in extreme conditions (e.g. very high or low temperatures) are know as extremophiles.

Organisms have special features (adaptations) that allow them to survive in their habitat. For example cacti have roots that reach deep into the ground to absorb as much water as possible from the dry desert conditions. They also have thin, spiny leaves that have a small surface area and so do not lose much water. The spines also protect the plant from animals which may wish to eat it. The camel has also adapted to its desert environment with a storage (hump) of fat on its back that can be converted to water when there is none avaliable, long eyelashes to keep sand out of its eyes and a tough mouth so it is not damaged by a cacti's spiny leaves. 

Surface to volume ratio:

The larger the animal, the smaller the surface area. This means that there is less surface exposed compared to the size of the animal. 

Animals that live in cold conditions tend to be large and have a small surface area. As they have a smaller surface area it means that less heat is lost through the surface of their skin. Artic animals also have a layer of fat or blubber under the skin which insulates them and can be used to survive on when food is scarce. They also have thick fur to keep them warm. 

Animals that live in hot, dry conditions are usually small, meaning their surface to volume ratio is large. This allows them to lose heat easily keeping them cool. Other adaptations include little or thin fur to allow heat to escape and no body fat under the skin. Many can survive on little water. 

Camoflage is an important adaptation. It is important for prey (to avoid detection from predators) and important for predators (to avoid detection from prey). Artic animals often change their coats as the landscape is very different from winter to summer, allowing them to be camoflaged in all seasons. 

Surface area to volume ratio is very important to plants. In hot, dry conditions most plants have leaves that are thin and small to keep a small surface so less water is lost. Some plants have curled leaves to trap moisture and reduce surface area. Some plants have very thick cuticles (waxy layer on leaves) that stops water escaping. Many desert plants are adapted to have very large root systems to collect the most amount of water. 

Animals mainly compete for food, territory and mates.

Herbivores have adapted to survive on a wide range of plants as it is unlikely they would survive depending on only one type of plant. Carnivores are in competition with their own and other species although they often try to avoid direct competition with another species. They are often fast and sharp eyed to catch prey. Prey animals compete to be the one which isn't caught! Some animals have adapted to be poisonous to their predator with bright, warning colours to stop a predator eating them. Other animals, although not poisonous, have adapted to have the bright, warning colours to make the predators believe they are poisonous and avoid them. 

Animals fight for territory as a territory allows them to have enough food and enough space to reproduce. 

Animals compete for mates. This is sometimes by fighting so the strongest male wins the female or the most attractive males, for example male peacocks are brilliantly coloured to attract attention. 

Plants compete for light, water, space and nutrients in the soil. 

Large plants such as trees take up a lot of the avaliable light, water and space. This is why plants such as snowdrops have adapted to flower very early in the year when light can come down through the bare branches and the dormant trees are not absorbing much water. Snowdrops also use nutrients from the dead leaves dropped by the trees. This way they can flower and germinate for the following year before the trees are in full leaf.

Plants that are underneath bigger ones blocking the light have mainly adapted to have large surface area leaves to absorb as much light as possible and may grow tall very quickly in order to reach the light. 

In order to not be in direct competition for space with their offspring, plants will release the seeds in a way so that they are either removed by air (e.g. dandelion seeds) or water in order for them to grow far away from the parent plants. Some plants release seeds in an explosion, flinging them from the parent, others have small hooks to become attached to passing animals. However some plants, mostly in the desert, release a poison so that the offspring can not grow in an area nearby, killing the competition before it has a chance to live!