Adaptations, Interdependence and Competition » Adaptations

What is an adaptation?

Every organism lives in a place with its own conditions. It might be hot or cold, wet or dry, bright or dark. Organisms have features that let them survive in the conditions where they normally live. These features are called adaptations.

An adaptation is a feature the organism has, not something it chooses or decides to develop. A feature that helps an organism find food, get water, stay safe or keep the right temperature gives it a better chance of surviving.

Key terms:

• Adaptation: a feature that enables an organism to survive in the conditions in which it normally lives.
• Structural adaptation: a feature of the body's shape or structure, such as fur, spines or a thick layer of fat.
• Behavioural adaptation: the way an organism acts, such as migrating or hiding in a burrow.
• Functional adaptation: something that happens inside the organism's body, such as a process, that helps it survive.
• Extremophile: an organism that lives in a very extreme environment.

The three types of adaptation

Adaptations may be structural, behavioural or functional. A good way to remember them is: how it looks, how it acts, how it works inside.

Adaptations to a hot, dry desert

Deserts have little water and very hot days. Organisms that live there have a range of adaptations.

• Cactus (structural): it has a thick stem that stores water. Its leaves are reduced to spines, which have a small surface area, so very little water is lost. Its roots spread out widely near the surface to soak up rain quickly.
• Camel (structural): it has wide feet that spread its weight so it does not sink into soft sand. It has long eyelashes that help keep sand out of its eyes.
• Camel (functional): it makes concentrated urine to save water.
• Many small desert animals (behavioural): they stay in a cool burrow during the heat of the day and come out to feed at night.

Adaptations to a cold environment

• Polar bear (structural): thick fur and a layer of fat under the skin reduce heat loss. White fur makes it hard for prey to see it against the snow.
• Migrating birds (behavioural): they leave when conditions get harsh and return when food is plentiful.

The same feature can help in more than one way. A polar bear's white fur is a structural adaptation, and it also helps the bear hunt.

Explaining adaptations from information

You should be able to explain how organisms are adapted to live in their natural environment, given appropriate information. You may be shown a photo or a description of an organism you have never met. You do not need to know it in advance. Use these steps:

1. Identify the conditions the organism lives in (cold, dry, dark, windy, salty).
2. Pick out the feature in the information.
3. Say what the feature does.
4. Link that to survival in those conditions, using the word because.

Extremophiles

Some organisms live in environments that are very extreme. The conditions might be very high temperature, very high pressure or a very high salt concentration. These organisms are called extremophiles.

Most organisms would die in these places. An extremophile has adaptations that let it carry on living there.

Bacteria in deep sea vents

A deep sea vent is a crack in the sea floor where hot water comes out. It is deep and dark, with very high pressure and high temperatures. The spec names bacteria living in deep sea vents as extremophiles. They live in conditions that would kill most other organisms.

Exam-style question

(a) A camel lives in a desert. Name one structural adaptation of a camel and explain how it helps the camel survive. [2 marks]

(b) Some bacteria live near deep sea vents, where the temperature and pressure are very high. What name is given to organisms that live in extreme environments? [1 mark]

(c) Some birds fly to a warmer country for the winter. What type of adaptation is this? [1 mark]