Biology GCSE Part1B

ADAPTATION IN ANIMALS

Living organisms have special features, known as adaptations, to allow them to survive in their particular habitat.

Animals in cold climates 

• you lose heat through your body surface - mainly your skin
• The amount you lose is closely related to your surface area : volume (SA/V) ratio
• The lower the ratio  the more body heat you can retain
• Think of two cubes
  • one has sides of 1cm - each side is 1sq cm - so total surface area is 6 sq cm
  • Volume is 1* 1* 1 = 1 cubic centimetre
  • ratio is 6:1
  • Now do the same with a cube of sides of 3 cm - each side has a surface area of 9 sq cm - so total surface area for 6 sides = 54 sq cm
  • Volume = 3 * 3 * 3 = 27 cubic centimetres
  • ration is 54:27 = 2:1
  • The larger cube has a much lower ratio
• This is why so many arctic animals are relatively large - polar bears, seals and walruses
• The surface area of places where the skin is thinnest e.g. ears are very small
• A thick layer of fat - blubber that builds up under the skin
• A thick fur coat outside will insulate well
• The fat layer also provides food supply - built up in summer when food is plentiful and used in winter when food is scarce
• Camouflage - many animals, including the arctic fox, the arctic hare and the stoat change the colour of their coats to pure white in winter

Surviving in dry climates

• Dry climates are often hot climates - like deserts
• Deserts
  • scorching heat in the day and bitter cold at night
  • lack of water
  • need to stop body temperature rising too high
• Many desert animals need little or no water - getting all they need from the food they eat
• Desert animals are often active in early morning and late evening when the temperature is most comfortable
• They rest in the heat of the day and in the night
• They are found in burrows well below the surface where the temperature is more constant
• Many desert animals are small - their SA/V is high
• Large thin ears to help lose heat
• not much fur
• ralatively little body fat
• the wrinkly skin on an elephant increases the surface area and the SA/V to aid heat loss

Key points:-

• All living things have adaptations to help them survive the conditions where they live
• Animals which are adapted for cold environments are often large, with a small surface area - volume ratio (SA/V). They have thick layers of fat and fur.
• Changing coat colour in the differnt seasons gives animals all year round camoflauge
• Adaptations for hot, dry environments include a large SA/V ratio, thin fur, little body fat and behaviour patterns that avoid the heat of the day.

ADAPTATION IN PLANTS

No plants can grow :-

• in deep oceans where there is no light
• in the icy wastes…