animal behavior

Animal BehaviorOrientation behaviours:

KinesesTaxes

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Environmental Stimuli

• A slater retreating to a daytime crevice could be responding to the dampness, darkness or coolness.

• Can experiment to determine which factors influence behaviour

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ExperimentsChoice chambers offer alternative conditionsFair test - all others factors are kept the same.

• Can test effect of temperature, light, humidity

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Simple Responses - immediate surroundings

Kineses and Taxes have an immediate benefit e.g. a slater moving into a damper place.

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TaxesMovement towards or away from a stimulus

Negative = away

Positive = towards

Taxes

Snails climb vertically upwards.

Negative geotaxis

Taxes

Mosquitoes home in on warm flesh.

Positive thermotaxis

Taxes

Blowfly maggots move rapidly away

from a directional

light source.

Negative phototaxis

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Positive phototaxis

Positive phototaxis = movement towards the light e.g. many swimming algae

Positive Chemotaxis

eg male moths following a pheromone trail given off by females

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Negative PhototaxisSlime Mold

The direction of the light source is indicated by white rectangles.

e.g. earthworms

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Positive chemotaxis

When a capillary tube filled with glucose is placed in a medium containing E. coli, the bacteria alter their locomotion so that they congregate near the opening of the tube.

Mosquitoes towards people along CO2 gradient

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Positive rheotaxisMovement against a current

e.g. salmon migrating upstream

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Kinesis• Animals have specific needs (eg food, humidity)• No information about the location of resource? • Undirected search

• Kinesis = random movement due to the presence of a stimulus. The rate of activity is determined by the intensity of the stimulus – not the direction

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Search methods• Undirected search: animal moves in a more

or less straight line through unsuitable habitat.

• Directed search: when it begins to perceive better conditions (the blue area) it slows down and turns sharper angles to stay in the vicinity of the improved conditions.

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stim

ulus

random movements to get awayslow down as animal gets further away

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stim

ulus

ALTERNATIVELYanimal moves directly away in a straight line

Hydrokinesis

Orthokinesis = stimulus intensity determines speed

e.g. slater’s rate of movement is inversely proportional to the humidity

Thermokinesis

Klinokinesis = stimulus intensity determines rate of turning eg lice turn less often at 30° - straight line. Human skin temp is about 35° lice more likely to linger at 35°.

Human body louse

35 o 30 o

Orthokinesis and klinokinesis movies