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Temperature Regulation. identify the broad range of temperatures over which life is found compared with the narrow limits for individual species
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Temperature Regulation identify the broad range of temperatures over which life is found compared with the narrow limits for individual species compare responses of named Australian ectothermic and endothermic organisms to changes in the ambient temperature and explain how these responses assist temperature regulation NEXT
Temperature • Temperature is one of the many limiting factors that can determine the presence of life on Earth. • Chemical reactions that take place in cells occur within a relatively narrow range of temperatures due to the temperature sensitivity of enzymes. • Tissue temperatures above 42 °C causes important enzymes to denature resulting in reduced ability to function and affecting metabolism. Temperatures above 100 °C causes proteins and DNA to denature, resulting in cell death. NEXT
Temperature and organisms • Living creatures can survive in temperatures as low as -70 °C at the poles or as high as 56 °C in deserts and 350 °C in hot vents in the sea. • HOWEVER, individual species cannot survive in an environment with a temperature range this large. They need much narrower ranges. • The temperature range in which a species can survive is known as its tolerance range for temperature. This is the degree to which an organism can tolerate and survive a significant variation in environmental factors including extremes such as drought, salinity and flood. NEXT
Examples The most heat tolerant organism known is the Pompeii worm (Alvinellapompejana). It lives in tubes on the sea floor near hydrothermal vents. They have been found to be living in water with a high temperature of 80°C and a low of 22°C NEXT
Australian examples The water-holding frog (Cyclorama platycephala) can survive between temperatures of 3°C and 39°C NEXT
Australian examples • Some Australian plants can survive the extreme heat of fires. • The banksia relies on the heat of the fire for seed release. Bottlebrush trees have buds in a protected position beneath the bark which resprout after fire. NEXT
Ectotherms • Have a limited ability to control their body temperature • Their cellular activities generate little heat • Their body temperature rises and falls with ambient temperature changes NEXT
Examples of ectotherms From the list below select the ectotherms Plants Amphibians Mammals Reptiles Marsupials Birds Fish Invertebrates NEXT
Endotherms • Their body metabolism generates heat • Metabolic processes maintain an internal body temperature that is independent of the external temperature. • To do this requires energy, so more food is required by the endotherms. NEXT
Examples of endotherms From the list below select the endotherms Plants Amphibians Mammals Reptiles Marsupials Birds Fish Invertebrates NEXT
Australian ectothermic organisms Central netted dragon Eastern brown snake Bogong moths
Central netted dragon The central netted dragon (Ctenophorusnuchalis) is an Australian desert-adapted lizard that inhabits central Australia’s plains and open scrub. It is able to withstand variations in body temperature from 13 to 44°C. The central netted dragon climbs up into trees or bushes when it is very hot to seek cooler conditions off the ground. It will then emerge at night to hunt when it is cool. In low ambient temperatures, the dragon will lie in sunlight and alter its body position to expose more of its body surface area to the sun’s rays. This increases its core body temperature. NEXT
Central netted dragon The central netted dragon seeks shelter when it is too hot and exposes its body to the sun to increase core temperature. This is an example of a: Behavioural adaptation Structural adaptation Physiological adaptation
Eastern brown snake The eastern brown snake (Psudonajatextilis) is found in the hot, dry areas of Australia, along the eastern sea board. The inhabit a wide variety of habitats including open grasslands and desert scrub. They are usual diurnal (awake during the day), but can become more active at night if the daytime temperature is too hot. If the temperature is too low, they bask in sunlight to gain additional heat. In very cool weather, they become less active, slowing down their metabolism and using fat reserves. If the cold period is prolonged, for example in winter, the snake will hibernate in a sheltered spot. NEXT
Eastern brown snake Being active at night is referred to as being: Diurnal Hibernation Nocturnal
Eastern brown snake The eastern brown snake becomes more active at night when the ambient temperature is too high for them. This is an example of a: Behavioural adaptation Structural adaptation Physiological adaptation
Bogong moths Bogong moths (Agrotisinfusa) migrate in huge swarms to the Australian alps in summer to aestivate cool caves. Aestivation is a term that is used for animals that ‘hibernate’ in hot conditions. Arriving around November, Bogong Moths cover the walls of alpine caves over summer – up to 17 000 moths in one square metre. They create a massive influx of high-fat, high-protein food to alpine ecosystems and are feasted upon by marsupials. NEXT
Australian endothermic organisms Common bentwing bat Fairy penguins Mountain pygmy possum
Common bentwing bat The common bentwing bat (Miniopterusscheribersii) produces brown fat in late summer and through autumn when food is abundant. Brown fat is a special heat producing tissue that can be quickly metabolised in cold conditions. In the cold winter months, periods of torpor can last up to 12 days. Torpor is a period of temporary hibernation. The brown fat can be metabolised and is used to increase the body temperature, allowing these bats to fly after periods of torpor. NEXT
Fairy Penguins The fairy penguin (Eudyptula minor) is found along the southern Australian coastline and in Tasmania and New Zealand. It is the smallest of all penguins and lives in burrows in coastal sand dunes. Fairy penguins have feathers that provide an insulating layer, trapping a layer of air close to the skin reduces the amount of heat lost. NEXT
Fairy penguins In cold weather the feathers of a fairy penguin would lie: Close to the skin Away from the skin They don’t change
Boo yah! In cold conditions, the feathers of the fairy penguin are lifted away from the skin, increasing the air layer and providing a greater degree of insulation. In hotter conditions, the fairy penguins’ feathers lie flat against the skin, trapping a smaller amount of air. NEXT
Fairy penguins Fairy penguins can regulate their body temperature via behavioural mechanisms. In warmer ambient conditions, they can move into the water to cool down. In cool conditions, they can huddle close together to reduce the surface area of each penguin exposed to the cold. They may also retreat to their burrows. NEXT
Mountain pygmy possum The mountain pygmy possum (Burramys parvus) lives above 1400 metres in the alpine regions of south-eastern Australia. It has short legs, a round body and small ears with limited circulation which assist in minimising heat loss. In prolonged cold, during winter months, they hibernate and go into a state of torpor. The pygmy possums curl into a ball, drawing all appendages in towards the body to reduce the surface area exposed to the cold. They also use a burrow to shelter from the cold in shorter periods of low ambient temperature. NEXT
Mountain pygmy possum To avoid overheating, mountain pygmy possums are nocturnal marsupials. During the day they shelter in rock crevices and this behaviour allows them to avoid exposure to excessive temperatures (and predators) and to keep their metabolic rate low during the heat of the day. NEXT
Mountain pygmy possum The mountain pygmy possum has short legs, a round body and small ears. This is an example of: Behavioural adaptation Structural adaptation Physiological adaptation
Adaptations analyse information from secondary sources to describe adaptations and responses that have occurred in Australian organisms to assist temperature regulation NEXT
Adaptations Adaptations are characteristics that increase the survival and reproductive chances of an organism in its environment. NEXT
Adaptations Adaptation is not: A change that an organism makes in response to the environment to help it survive A variation that arises in individuals and have a genetic basis
Adaptations • Adaptation is usually a variation that arises in individuals and has a genetic basis. • Natural selection acts upon these variations so that those that suit the organism to its environment are passed on within a population. NEXT
Adaptations Natural selection is also known as: Flight or fight Survival of the fittest Convergent evolution
Adaptations Adaptations are divided into three major categories. Behavioural Structural Physiological
Behaviouraladaptations • Behavioural adaptations are adaptations to the way the organism acts • They are displayed by both ectotherms and endotherms Controlling exposure Nocturnal activity Migration
