Responding to Responding to the Environmentthe Environment

Animal SurvivalAnimal SurvivalSee pages 138 – 141 Torrance

Responding to the Responding to the EnvironmentEnvironment

Animals and plants are subject to Animals and plants are subject to Environmental Environmental Stimuli.Stimuli.

Temperature changes , pH changes, changes in Temperature changes , pH changes, changes in light intensity, chemicals ,food are all examples light intensity, chemicals ,food are all examples ofof environmental stimulienvironmental stimuli

A living organism will either A living organism will either move towardsmove towards or or away fromaway from a a stimulusstimulus

Responding to the Responding to the EnvironmentEnvironment

OrganismOrganism StimulStimulusus

ResponResponsese

Survival valueSurvival value

WoodlousWoodlousee

lightlight Moves Moves awayaway

Keeps skin moist Keeps skin moist and avoids and avoids predatorspredators

ParameciParamecium um

Weak Weak acidacid

Moves Moves towardtoward

Paramecium Paramecium feedsfeeds on bacteria on bacteria that live in acid that live in acid conditionsconditions

Blow fly Blow fly maggotsmaggots

lightlight Moves Moves awayaway

Dark places Dark places provide provide foodfood ,water and ,water and sheltershelter

Responding to the Responding to the EnvironmentEnvironment

A response to an environmental stimulus is of A response to an environmental stimulus is of survival valuesurvival value to an organism e.g. Avoid to an organism e.g. Avoid predators, prevent drying out etc.predators, prevent drying out etc.

A A choice chamberchoice chamber can be used to see how a can be used to see how a stimulus affects a living organism stimulus affects a living organism

In a choice chamber, organisms are faced with In a choice chamber, organisms are faced with two different environmentstwo different environments. They will congregate . They will congregate in the environment which in the environment which suits them bestsuits them best. This . This allows us to determine the most suitable allows us to determine the most suitable conditions for their survival. conditions for their survival.

Woodlice prefer moist conditions – it prevents them drying out.

They move quickly when in dry conditions to increase their chance of leaving the unfavourable environment and finding a more suitable one.

They move more slowly or stop when it is moist, increasing their chance of staying in the favourable environment.

E.g.Wet Dry

woodlice

Choice chamber

How do woodlice respond to How do woodlice respond to light? – light? – ((An example of a stimulus and response)An example of a stimulus and response)

WoodliceWoodlice respond to light. respond to light.

The following experiment is set up to find out ifThe following experiment is set up to find out if

A) they move A) they move towardstowards the light the light

oror B) they move B) they move awayaway from the light from the light

How to set up a choice How to set up a choice chamberchamber

AA choice chamber choice chamber (½ black and ½ light) is collected. (½ black and ½ light) is collected.

A piece of A piece of gauzegauze is placed inside as a is placed inside as a platform for the platform for the woodlice to walk on.woodlice to walk on.

10 woodlice 10 woodlice are added to the chamber at the centre holeare added to the chamber at the centre hole

It is left for It is left for 10 minutes10 minutes and every 2 minutes the number and every 2 minutes the number of woodlice in each side are counted.of woodlice in each side are counted.

Black cover

(dark side)

gauze

Light side

Time (mins)

0246810

ResultsResults

Time Time (min)(min)

Number of Number of organisms on the organisms on the lightlight side of the side of the chamberchamber

Number of Number of organisms on the organisms on the darkdark side of the side of the chamberchamber

00

22

44

66

88

1010

5 5

4 6

2 8

64

1 9

0 10

ConclusionConclusion

The organism responded to the light stimuli by The organism responded to the light stimuli by moving moving awayaway from it. from it.

Why?Why?

They avoid being seen and eaten by predators

They avoid drying out in sunlight

Responding to the Responding to the EnvironmentEnvironment

Rhythmical BehaviourRhythmical Behaviour

This is a type of behaviour This is a type of behaviour repeatedrepeated at regular at regular intervalsintervals

It is usually triggered by an external It is usually triggered by an external stimulusstimulus e.g. e.g. daylengthdaylength or or temperaturetemperature

Responding to the Responding to the EnvironmentEnvironment

Type of Type of RhythmRhythm

AnimalAnimal RhythmicRhythmical al behaviourbehaviour

External External trigger trigger stimulusstimulus

SignificancSignificancee

TidalTidal FiddleFiddler crabr crab

Active at Active at high tide high tide inactive inactive at low at low tidetide

MovemenMovement of tide t of tide caused by caused by the moonthe moon

Enables Enables crab to find crab to find foodfood

CircadiaCircadiann

(daily)(daily)

CockroacCockroachh

Active at Active at nightnight

Onset of Onset of darknessdarkness

Can feed Can feed unseen by unseen by predatorspredators

AnnualAnnual SwalloSwalloww

MigrateMigrates to s to warmer warmer climatesclimates

Onset of Onset of shortershorter

day day lengthslengths

Escapes cold Escapes cold temperaturetemperatures and food s and food shortageshortage in in winterwinter

Daily ChangesDaily Changes

These changes occur every 24 hours.These changes occur every 24 hours.

The most obvious is light and dark.The most obvious is light and dark.

Many animals have adapted their behaviour to Many animals have adapted their behaviour to being active and feeding during the day being active and feeding during the day ((DIURNALDIURNAL animals) whereas others are active at animals) whereas others are active at night (night (NOCTURNALNOCTURNAL animals). animals).

Diurnal Animals

Nocturnal AnimalsNocturnal Animals

Tidal ChangesTidal Changes Most Most seashore animalsseashore animals show some adaptations show some adaptations

to the to the tidaltidal movement. movement. Tidal movement occurs Tidal movement occurs twicetwice daily – i.e. daily – i.e. at high at high

tidetide and and low tidelow tide..

Shore Shore CrabCrab

Rhythmical Behaviour in Rhythmical Behaviour in Shore CrabsShore Crabs

Daily tidalDaily tidal changes bring about a rhythmical changes bring about a rhythmical behaviour pattern in many seashore animals.behaviour pattern in many seashore animals.

The shore crab regulates its period of The shore crab regulates its period of activityactivity to to coincide with the movement of the tide – coincide with the movement of the tide – activeactive at at high tidehigh tide

The The shore crabshore crab is found in is found in rock poolsrock pools..

Advantages of daily rhythmical Advantages of daily rhythmical behaviourbehaviour

Avoids Avoids predatorspredators

More More foodfood available when active available when active

Annual ChangesAnnual Changes

Over the period of a year there Over the period of a year there are are seasonal changesseasonal changes..

During summer the number of During summer the number of daylight hours (daylight hours (daylengthdaylength) is ) is greater than in winter.greater than in winter.

Annual RhythmAnnual Rhythm Rhythmical behaviourRhythmical behaviour occurs in response to occurs in response to

regular changes in the environment.regular changes in the environment.

In animals, environmental stimuli like In animals, environmental stimuli like changing changing daylengthdaylength, light and dark, etc. can set off certain , light and dark, etc. can set off certain responses responses

AnnualAnnual rhythmical behaviour occurs is rhythmical behaviour occurs is repeated repeated every year.every year.

MigrationMigration, , hibernationhibernation and and courtshipcourtship are are examples of annual rhythmical behaviour examples of annual rhythmical behaviour brought about by brought about by changes in daylengthchanges in daylength..

CourtshipCourtship

Most Most birdsbirds produce produce their eggs soon after their eggs soon after mating, and hatching mating, and hatching occurs a occurs a few weeksfew weeks later.later.

In contrast, In contrast, red deerred deer don’t have their young don’t have their young until until 6 months6 months after after mating.mating.

Advantages of Advantages of CourtshipCourtship

Courtship behaviourCourtship behaviour ensures that reproduction ensures that reproduction occurs at a time of year that makes sure that occurs at a time of year that makes sure that young are born when:young are born when:

Weather conditions are Weather conditions are goodgood and and food is food is plentiful.plentiful.

This means the young have a This means the young have a better chance of better chance of survival.survival.

HibernationHibernation During During severe wintersevere winter

conditions, conditions, foodfood is in is in shortshort supply.supply.

The more an animal The more an animal moves around looking for moves around looking for food, the more energy it food, the more energy it uses.uses.

During During severe winterssevere winters the the animal may die.animal may die.

During hibernation, the animal goes into a type of “sleep”.During hibernation, the animal goes into a type of “sleep”.

Before they go into hibernation the animals Before they go into hibernation the animals must must increase their feedingincrease their feeding to build up reserves to build up reserves of food which can be used over the period of of food which can be used over the period of hibernation.hibernation.

HedgehogsHedgehogs, , bears bears andand squirrels squirrels are are examples of examples of hibernating hibernating mammals.mammals.

Advantages of Advantages of HibernationHibernation

To overcome this problem of To overcome this problem of energy lossenergy loss and to and to increaseincrease the chance of the chance of survivalsurvival during the during the winter, some animals winter, some animals hibernatehibernate..

The animal The animal reducesreduces its rate of its rate of using energyusing energy by by stopping movement and reducing it’s body stopping movement and reducing it’s body temperature.temperature.

MigrationMigration

MigrationMigration is an is an annual annual rhythmrhythm

Animals migrate to Animals migrate to places where there places where there is is more foodmore food

SwallowsSwallows, , salmonsalmon and buffalo migrateand buffalo migrate

AdvantagesAdvantages of of migration behaviourmigration behaviour

Avoids Avoids food shortagesfood shortages

Avoids Avoids harsh wintersharsh winters

Allows Allows longer dayslonger days for for feedingfeeding