Download Adaptations of plants and animals

Adaptations of plants and animals
Plants and animals are often seen to be well adapted to their role within nature. There is a
suggested reason as to why this is true.
Natural Selection
Natural selection is the process by which animals (and plants) changed and ultimately, only
those, which were able to survive in the climate survived. The climate has also changed
within the years and this has aided to the natural selection process.
One example, which is often used, is the giraffe. It is said that at one point there was a lack
of leaves on the lower part of the trees where the “giraffes” (of course, they were not as we
think of them now) lived. (This could have happened due to too many giraffes present in the
area – so not enough leaves were present.) There were, by chance, a few “giraffes” which
had longer necks than other and so they were able to reach the leaves and survive, whereas
the others died. Therefore, the giraffes with the longer neck survived and the others died –
and so now we only see giraffes with long necks.
Other examples of possible natural selection are shown throughout nature: camouflaging in
animals – these would be the likely ones of that species to survive – the others would have
been eaten by predators. Speed of certain animals and many other adaptations…
Examples
Dessert Animals
What are the problems that dessert animals would face?
• lack of water in the environment
• the temperature is so high that they would need to lose heat
So…let’s look at some of the animals!
Camel
-
hump / 2 humps
o to store fat – this is used as insulation from the sun – so that no heat is
gained
-
long loops of Henley
o (as we will find out later) more absorption of water – less wasted in urea
-
however, heat is gained during the day (approximately 5ºC).
o this is lost via the belly at night – there is no fat in the belly
-
fat has a high hydrogen : oxygen ratio.
o when the fat is oxidised, water is produced
-
dry faeces are produced
o less water loss
Desert Rat
-
very long loops of Henley
o again, this produces very concentrated urine – and useful substances are
reabsorbed more.
-
nocturnal
o only comes out at night – when it is cooler
-
produces very dry faeces
-
possess snouts
o this condenses moisture in the respiratory passages
So, those are a few examples…now let’s look at general adaptations of animals in hot
climates…
Features shared by many animals in hot climates
• large surface area : volume ratios
o although this means more heat is taken in, heat is lost quicker at a faster rate
• very angular – they are tall and skinny
o again, this helps them lose more heat rapidly (this is the same point as above!)
• large ears
o exposed capillaries to lose heat quicker
• light coloured
o to reflect heat
• lack fur / very thin fur
o so that air is not trapped as insulation
• long loops of Henley
o more concentrated urine – more water (and other useful material) reabsorbed
• dry faeces
o less water loss
• may be nocturnal
o temperature is lower at night – so less heat is lost
OK…so animals do have adaptations…but plants are also living – and require certain
conditions to live in…do they adapt? I’m sure there are cactuses in the desert…
How plants adapt to the hot climates
• surface area : volume ratios reduced (opposite to animals)
o smaller surface area means less stomata – so less water is lost by transpiration
• leaves reduced to spines
o again, this means less/no stomata: i.e. no water vapour is lost
• stem is main photosynthetic organ
o because the leaves are spines, they are unable to absorb sunlight; the stem can
• less surface area
o less water loss
• very very long and deep roots
o the longer the roots, the more soil they penetrate and so the more water they
gain
• long surface roots
o this enables the plant to absorb condensed moisture at night
• reduced transpiration:
o waxy cuticle
o reduced number of stomata – only open at night
o sunken stomata – not open to the wind – meaning less water vapour lost
o hairs around stomata – to prevent wind
o rolled leaf – to hide stomata
o thin leaves – giving a low heat capacity
-
the reason for this is because too much heat would damage the enzymes which
are used for photosynthesis