11-14yrs - adaptations to arid habitats - classroom presentation - science

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  • 7/28/2019 11-14yrs - Adaptations to Arid Habitats - Classroom Presentation - science

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    Adaptations to Arid Habitats

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    Where are arid habitats

    found?

    Estimates suggest that arid and semi arid habitats accountfor more than one third of the earths land surface

    Credit: U. S. Geological Survey

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    Lack

    of food

    What are the challenges of living in

    an arid habitat?

    Lack of

    plants

    Movement

    Lack of water

    HotCold

    Temperature

    Challenges?

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    the process whereby a species evolves character ist ics

    that enable it to surv ive in a part icular habitat

    What is adaptation?

    Adaptations allow species to live successfully in their

    habitat

    Species living in different habitats need differentadaptations

    Adaptations can be behavioural or physical

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    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

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    A flooded channel on the west coast of the island, a rare

    and important source of freshwater on Barrow

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    Mammals on Barrow Island

    Common wallaroo (Macropus

    robustus)

    Found across most of Australia, with one

    subspecies on Barrow Island

    Seeks shelter in caves and rockyoutcrops

    Can go for a few months without drinking

    Licks saliva onto forearms to help it loseheat through evaporation

    Stops breeding during prolonged

    droughts, but breeds quickly in good

    conditions

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    Other mammal examples

    Wild Bactrian camel

    Many adaptations to conserve

    water, cope in intense heat and

    survive sandstorms!

    Bat-eared fox

    Large ears to help dissipate heat

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    Fawn hopping mouse

    Can obtain water from seeds

    Produces concentrated urine + dry

    faeces

    Shelters in a burrow during day

    Kangaroo rats

    Nasal counterflow system reduces

    water lost through breathing

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    Amphibians on Barrow

    Island

    Mains frog (Li tor ia maini)

    Only amphibian species found on

    Barrow Island

    Spends the dry season underground in

    a state of torpor

    Produces a membrane over the skin to

    prevent drying out

    Only emerges after rainfall

    Eggs laid in temporary pools, tadpoles

    develop quickly

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    Other amphibian examples

    Green tree frog

    Takes refuge in any available

    water sources, including pipes,

    water tanks and toilet bowls!

    Spotted marsh frog

    Shelters under logs and

    stones in the heat of the day

    Water holding frog

    Can reabsorb water stored in its

    bladder or pockets under the skin

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    Reptiles on Barrow Island

    Perentie (Varanus g iganteus)

    General adaptations common to

    reptiles

    Shelters underground or in rock

    shelters; basks in sun in early

    morning and late afternoon

    On very hot days, may shelter inshade or climb termite mounds or

    shrubs to get off hot ground

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    Other reptile examples

    Thorny devilTiny grooves over body direct

    moisture to the mouth

    Can change colour depending on

    temperature

    Desert tortoise

    Dormant during hottest part of

    summer (aestivation)

    Lives in burrows

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    Eastern sandfish

    Streamlined 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

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    Plants on Barrow Island

    Spinifex grass (Triodiaspecies)

    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.

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    Other plant examples

    Lava cactusStores water in thick

    stems, leaves

    reduced to spines to

    reduce transpiration

    Bristlecone pine

    Parts of the living

    tissue die back during

    drought. Can still

    produce cones and

    seeds when

    conditions improve

    Grandidiers

    baobab

    Stores water in trunk

    which can expand

    after rainfall

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    You will be given a worksheet with a list of adaptationsspecies use to survive in arid habitats.

    Your task is to decide whether each adaptation is a

    behavioural or a physical adaptation.

    Activity 1

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    Activity 1 - Answers

    Adaptation Behavioural? Physical?Being nocturnal

    Impermeable skin Producing concentrated urine

    Aestivation Panting

    Ability to withstand high body temperatures

    Seeking shade Ability to store water inside the body

    Light colouration Living in a burrow

    Large surface area Leaves reduced to spine Breed only after rainfall

    Nasal counterflow

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    Arid habitats are dry areas with little rainfall and areusually hot, although they can be cold at night.

    Arid habitats cover over a third of the Earths landsurface.

    Animals and plants have evolved a range of adaptationsto help them survive in arid habitats.

    These adaptations can be behavioural, such assheltering in a burrow during the heat of the day, orphysical, such as having a large surface area to loseheat more quickly.

    Summary

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    Activity 2The 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.