1. Animal senses: how they detect stimulus

2. Remember that sensory stimulation is often the starting point for behaviour. There are five or possibly six senses and that animal and human senses are not necessarily the same.

3. Photoreceptors (vision)
Many animals are sensitive to different ranges of the spectrum then humans. Bees see in ultraviolet but are less sensitive to red which is why most red flowers are either scented or have blue in them. Goldfish see far red and seabirds are very sensitive to red.
Animals detect colour in a variety of ways, many do not have colour vision at all, eyes are set up differently and most detect movement and speed of movement.

4. Thermo receptors (heat)
Many snakes have heat pit in front of their eyes and can detect infrared to locate prey.
Most animals use their skin to detect heat.

5. Mechanoreceptors (touch etc)
These receptors let an animal know which way is up in terms of gravity, they govern internal pressure (stomach, bladder), recognise the position of one part of the body to another.
Cats whiskers are tactile receptors, human skin, lateral line in fish
Proprioceptors respond to tension
in muscles and joints.

6. Chemoreceptor (smell and taste)
Smell is the detection of chemicals in air or water
Taste (gustation) is the detection of chemicals in the liquid or solid state.
Humans use nose and tongue but other animals have quite different organs: flies have taste hairs on feet, many insects smell with antenna, reptiles have Jacobson’s organ for sensing.
Pheromones are used to communicate between members of the same species.

8. Chemicals are used for:
Hunting to track and detect prey
Detecting predators
To recognise and check if food is ripe/safe
To recognise other members of the group
For defence (skunk)
For attack (spitting cobra)
To mark territory
For communication (especially insects)
For sexual attraction
To form an alarm
To make a chemical trail

9. Auditory receptors (sound)
Humans detect sound in waves with thiwer inner easr in the range of hz.
Sound above this range is ultrasonic
Bats, dogs, whales and insects can hear ultrasonic sounds.
Whales and dolphins also use echolocation

10. Electrical fields
Some debate over this being the ‘sixth sense’. Some fish have an electrical field around them and can pick up disturbance in that field.

11. Magnetic fields
Homing pigeons and some bacteria can detect the magnetic field lines of the earth.