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Adaptations to Arid Habitats

Adaptations to Arid Habitats. What is an arid habitat?. Arid habitats: are extremely dry receive little or no rainfall usually have high temperatures may suffer periodic droughts. Where are arid habitats found?.

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Adaptations to Arid Habitats

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  1. Adaptations to Arid Habitats

  2. What is an arid habitat? • Arid habitats: • are extremely dry • receive little or no rainfall • usually have high temperatures • may suffer periodic droughts

  3. Where are arid habitats found? Estimates suggest that arid and semi arid habitats account for more than one third of the earth’s land surface Credit: U. S. Geological Survey

  4. Lack of plants Lack of water Challenges? Lack of food Movement Hot Cold Temperature What are the challenges of living in an arid habitat?

  5. What is adaptation? “the process whereby a species evolves characteristics that enable it to survive in a particular habitat” • Adaptations allow species to live successfully in their habitat • Species living in different habitats need different adaptations • Adaptations can be behavioural or physical

  6. Barrow Island: Case Study - Approximately 70 km off the coast of Western Australia- Receives an average of 320 mm rainfall per year- Most of the island is covered by spinifex grassland- Nearly 2,600 different species have been recorded here

  7. A flooded channel on the west coast of the island, a rare and important source of freshwater on Barrow

  8. Mammals on Barrow Island Common wallaroo (Macropus robustus)Found across most of Australia, with one subspecies on Barrow IslandSeeks shelter in caves and rocky outcropsCan go for a few months without drinkingLicks saliva onto forearms to help it lose heat through evaporationStops breeding during prolonged droughts, but breeds quickly in good conditions

  9. Other mammal examples Wild Bactrian camelMany adaptations to conserve water, cope in intense heat and survive sandstorms! Bat-eared foxLarge ears to help dissipate heat

  10. Fawn hopping mouseCan obtain water from seedsProduces concentrated urine + dry faecesShelters in a burrow during day Kangaroo rats‘Nasal counterflow system’ reduces water lost through breathing

  11. Amphibians on Barrow Island Main’s frog (Litoria maini)Only amphibian species found on Barrow IslandSpends the dry season underground in a state of torporProduces a membrane over the skin to prevent drying outOnly emerges after rainfallEggs laid in temporary pools, tadpoles develop quickly

  12. Other amphibian examples Spotted marsh frogShelters under logs and stones in the heat of the day Water holding frogCan reabsorb water stored in its bladder or pockets under the skin Green tree frogTakes refuge in any available water sources, including pipes, water tanks and toilet bowls!

  13. Reptiles on Barrow Island Perentie (Varanus giganteus)General adaptations common to reptilesShelters underground or in rock shelters; basks in sun in early morning and late afternoonOn very hot days, may shelter in shade or climb termite mounds or shrubs to get off hot ground

  14. Other reptile examples Thorny devilTiny grooves over body direct moisture to the mouthCan change colour depending on temperature Desert tortoiseDormant during hottest part of summer (aestivation)Lives in burrows

  15. Eastern sandfishStreamlined body allows it to ‘swim’ through sand Saudi fringe-fingered lizardFringes of elongated scales on the toes help in moving across sand Sidewinder‘Sidewinding’ movement across loose sand

  16. Plants on Barrow Island Spinifex grass (Triodia species)Extensive root system to collect water both from the surface and underground.Roots can be up to 3 metres long.Leaves have a waxy, impermeable surface (cuticle) to reduce water loss.Leaves curl inwards into long pointed tubes to slow the rate of transpiration.

  17. Other plant examples Grandidier’s baobab Stores water in trunk which can expand after rainfall Lava cactusStores water in thick stems, leaves reduced to spines to reduce transpiration Bristlecone pineParts of the living tissue die back during drought. Can still produce cones and seeds when conditions improve

  18. Activity 1 You will be given a worksheet with a list of adaptations species use to survive in arid habitats. Your task is to decide whether each adaptation is a behavioural or a physical adaptation.

  19. Activity 1 - Answers

  20. Summary • Arid habitats are dry areas with little rainfall and are usually hot, although they can be cold at night. • Arid habitats cover over a third of the Earth’s land surface. • Animals and plants have evolved a range of adaptations to help them survive in arid habitats. • These adaptations can be behavioural, such as sheltering in a burrow during the heat of the day, or physical, such as having a large surface area to lose heat more quickly.

  21. Activity 2 The aim of this activity is to compare how effective different adaptations are at helping a species to conserve water. You will be given sponges soaked in water to represent your arid “animals”. You need to design an experiment to measure how much water your sponges lose under various conditions set up to represent different adaptations. You need to weigh the sponges before and after the experiment so that you can record how much weight (water) each has lost.

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