Adaptation is the process by which organisms become fitted to their environments through characteristics that allow them to survive. Polar bears, camels, and cacti each have adaptations that allow them to live successfully in their habitats of the Arctic, desert, and desert respectively. These adaptations include things like white fur and fat layers in polar bears, large flat feet and the ability to go long periods without water in camels, and water-storing stems and spines that reduce water loss in cacti.

1. Adaptation and Competition

2. Adaptation
Adaptation is the process by which an animal or plant species becomes fitted to its
environment.
Organisms are adapted to survive in different conditions.
Every organism has certain features or characteristics that allow it to live
successfully in its habitat. These features are called adaptations, and we say that
the organism is adapted to its habitat.Organisms living in different habitats need
different adaptations.

3. The Polar bear
Polar bears are well adapted for survival in the Arctic.
They have:
a white appearance, as camouflage from prey on the
snow and ice
thick layers of fat and fur, for insulation against the
cold
a small surface area to volume ratio, to minimise heat
loss
a greasy coat, which sheds water after swimming.

4. The camel
Camels live in deserts that are hot and dry during the day, but cold at night. They
are well adapted for survival in the desert. Camels have:
Large, flat feet to spread their weight on the sand.
Thick fur on the top of the body for shade, and thin fur elsewhere to allow easy
heat loss.
A large surface area to volume ratio to maximise heat loss.
The ability to go for a long time without water (they don't store water in their
humps, but they lose very little through urination and sweating).
The ability to tolerate body temperatures up to 42°C.
Slit-like nostrils and two rows of eyelashes to help keep the sand out.

6. Cacti
Cacti are well adapted for survival in the
desert. They have:
Stems that can store water.
Widespread root systems that can collect
water from a large area.
In addition, cacti have spines instead of
leaves. These minimise the surface area
and so reduce water loss by
transpiration. The spines also protect the
cacti from animals that might eat them.

8. Competition
Habitats have limited amounts of the resources needed by living organisms. Organisms can only survive if they can get enough
resources. They must compete with other organisms for these resources. If they are unsuccessful and cannot move to another habitat,
they will die.
Animals
Some of the resources that animals compete for:
food
water
space
Animals may also compete for mates so that they can reproduce.
Plants
Remember that plants make their own food using photosynthesis, so they do not compete for food. Some of the things that plants do
compete for are:
light
water
space
mineral salts

9. Mark, release and recapture method to calculate
population of animals
Mark and recapture is a method commonly used in ecology to estimate an animal
population's size. A portion of the population is captured, marked, and released.
Later, another portion is captured and the number of marked individuals within the
sample is counted.

11. For example, 10 animals were trapped, marked and released. Two days later, 20
animals were trapped. Of these, 5 were found to be marked.
Population size = 10 × 20/5 = 200/5 = 40

12. Try this question... it will only take you a minute!
I captured 50 fish from a lake. I marked a big cross on the back of each fish with a
permanent marker*...
I put the marked fish back in the lake and they happily swam away to join their
friends.
The next day I captured 20 fish from the same lake. 10 of them had a cross on
their back.
Can you estimate the total population of fish in the lake?

13. All living things within an ecosystem are interdependent. A change in the size of
one population affects all other organisms within the ecosystem. This is shown
particularly clearly by the relationship between predator and prey populations.
There is a continuous tussle between predators and their prey. Predator species
need to be adapted for efficient hunting if they are to catch enough food to survive.
Prey species, on the other hand, must be well adapted to escape their predators,
if enough of them are to survive for the species to continue.
If the prey population in an ecosystem grows, predator numbers will respond to
the increased food supply by increasing as well. Growing predator numbers will
eventually reduce the food supply to the point where it can no longer sustain the
predator population .

14. If the prey population grows, predator numbers
will respond to the increased food supply by
increasing as well. But the growing predator
population will eventually reduce the food supply
to the point where it can no longer be sustained.