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Many environments where organisms survive

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Multiple mechanisms are used by organisms to maintain their internal environment within limits they can tolerate to survive, in response to a changing environment and varied conditions.

List some environmental factors that organisms may need to respond to:

Extreme heat (for example)

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An animal that can generate its own body heat using adaptations to thermoregulate.

Thermo- "heat"

Regulate- maintain or control

These adaptations can be behavioural, structural or physiological.

Examples of Endotherms:

Bear

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Class extension question: Discuss the importance of maintaining internal body temperature? What happens when internal temperature is not maintained?

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Behaviour- how an organism acts.

Class question: What can an endotherm do to assist in thermoregulation and how does it affect temperature? Provide examples.

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Class question: What is the study of physiology referring to?

Physiological adaptations affect the functions occurring within the body.

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Seek shade: Finding shade and changing their position to reduce the amount of surface area exposed to the sun will help animals cool down in the hottest part of the day. For example, the red kangaroo will find shade, and sit in a position where its body provides shade for its hind legs and tail, to reduce the large surface area exposed to the sun. This helps with thermoregulation under the hot midday sun.

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Nocturnal animals remain ............. during the heat of the day, and ................ during the night.

This helps with thermoregulation because.....................

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Burrowing underground provides a thermal refuge when the outside temperature is too hot or too cold making it difficult for endotherms to thermoregulate.

For example, meerkats burrow underground to avoid the heat of the day, while rabbits burrow in snowy conditions to retain heat.

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Migration is the movement of animals to a different habitat that is within their temperature range. It means they can avoid the extremes of temperatures in the winter/summer.

For example, humpback whales migrate north to warmer waters during the harsh winter months, and south during the summer months to feed

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The amount of an endotherms body exposed to the air, or the surface area, will affect its thermoregulation. Animals can change their position to reduce the amount of surface area exposed to the cold air/wind.

In cold environments, penguins will huddle together which will increase/decrease the Surface Area exposed to the cold air, which will conserve/lose heat.

Dogs will curl up into a ball which will increase/decrease Surface Area. This will minimise heat gained/lost on a hot/cold day.

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Vaso- Vessel

Dilation- Expanding

Constriction- Reducing

Blood flow can be increased or decreased to regulate the amount of heat lost to surroundings.

Discuss:

In extreme hot weather, endotherms want to gain/lose additional heat. Vasodilation is the expanding of blood vessels, which brings the blood closer to the skin surface, resulting in more heat being lost through the skin and therefore promoting/minimising cooling.

In cold environments, vasoconstriction occurs, where the blood vessels constrict which increases/decreases blood flow and volume. This reduces/increases heat loss through the skin, therefore promoting/minimsing cooling.

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When water evaporates off a surface, it takes heat with it.

What physiological adaptation uses this process to aid in losing heat?

What other animals may benefit from this?

(hint: the picture provided)

Conversely, what happens when we are cold?

How does this increase body temperature?

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Blood flow is increased or decreased at extremities in order to control temperature. For example, penguins have shunts in their legs which minimises blood slowing to their feet when they are standing on frozen ice.

Predict how this minimises heat loss?

Bilby's have extensive capillaries in their ears to bring blood to large surface areas to aid heat loss.

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Fur, hair or feathers all provide insulation. In fairy penguins, feathers can lift away from the skin to create a greater degree of insulation and prevent heat loss in cold conditions. In warm conditions, the feathers sit close to the skin surface, which minimises insulation.

Australian fur seals are covered in a layer of blubber to minimise heat loss in cold water.

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Animals with a small surface area to volume ratio live in cold environments, where heat loss through the surface of their skin is minimal. For example, the mountain pigmy possum has very small ears to reduce heat loss to the environment.

Animals that live in hot environments have larger surface area to volume ratios, for example, African elephants have very large ears to maximise heat loss.

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Plants also need to regulate their heat. They do this through transpiration, which is the evaporation of water through leaves, to reduce heat. However, this means they also need to maintain their water balance particularly in dry environments.

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Some plants only open their stomata during the early morning and late afternoon.

Predict how will this affect water maintenance?

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Some plants have dry, woody fruit instead of moist, fleshy fruit, such as oranges, to reduce water loss when the fruit falls off to disperse seeds.

An example is the banksia flower.

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Other than transpiration, plants have adapted other structural and structural adaptations to reduce their temperature and minimise water loss.

These include:

a thick, waxy coating over leaves making them waterproof and minimising water loss through transpiration, like eucalypt leaves

Some leaves have very fine white hairs which reflect sunlight, and so minimise transpiration while minimising excessive heat

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Sunlight will heat the plant and cause transpiration and major water loss.

To minimise this, plants have adaptations to minimise their light exposure.

For example,

small sized leaves, or even spines, for example in cacti

'droopy' hanging leaves to reduce the surface area to the heat of the midday sun

reduced size of flowers meaning less water is needed

reduced surface area of organs with the highest amount of stomata