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