Animal BehaviorOrientation behaviours:

KinesesTaxes

2

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

3

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

• Can test effect of temperature, light, humidity

4

Simple Responses - immediate surroundings

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

5

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

9

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

11

Negative PhototaxisSlime Mold

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

e.g. earthworms

12

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

13

Positive rheotaxisMovement against a current

e.g. salmon migrating upstream

14

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

15

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.

16

stim

ulus

random movements to get awayslow down as animal gets further away

17

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