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Animal Senses

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Animal Senses How do animals sense stimuli? Sensory organs perceive stimuli (light, sounds, etc.) with a receptor cell. The receptor cell sends signals to the brain ... – PowerPoint PPT presentation

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Title: Animal Senses


1
Animal Senses
  • How do animals sense stimuli?
  • Sensory organs perceive stimuli (light, sounds,
    etc.) with a receptor cell. The receptor cell
    sends signals to the brain where they are
    processed and integrated.

2
Animal Senses
  • Each type of animal is equipped with its own
    sensory receptors ? each animal perceives its
    environment differently.

3
Animal Senses
  • Animal senses are more varied and sharper than
    human senses.
  • Most sensory receptors are found on the head of
    an animalin most cases, the head is the first
    part of an animal to enter a new environment

4
Four Basic Modalities
  • Photoreception response to light

5
Thermoreception
  • Response to heat!

6
Mechanoreception
  • Response to movement.
  • This includes hearing, vibration, touch, balance,
    etc.

7
Chemoreception
  • Response to chemical energy, including smell and
    taste

8
Insect Senses - Vision
  • Compound eyes - made up of 100s 1000s of
    lenses
  • Each individual eye is not as accurate as a
    vertebrate eye, but the compound eyes taken
    together are better at detecting motion.
  • Respond to minute changes in color and motionthe
    brain produces 1 detailed image.

9
Insect Chemical Receptors
  • For taste and smell
  • Found on mouthparts, antennae and legs.
  • A flys foot can tell whether a liquid contains
    sugar or salt.

10
Sensory Hairs
  • Found mostly on head and legs
  • Can detect movement in surrounding air or water,
    and can detect certain chemicals.

11
Sensory Hairs detect Pheremones
  • These are odor producing molecules that act as
    chemical messages.
  • They are synthesized by an individual, released
    into the environment and change the behavior of
    another individual.

12
Sensory Hairs detect Pheremones
  • 1000 different insect pheremones known
  • Most are produced by females and are airborne.
  • Species specific sex attractants.

13
Animal Senses
  • Specific examples
  • A homing pigeon senses changes in altitude as
    minute as four millimeters. Pigeons also see
    ultraviolet light and hear extremely
    low-frequency sound.

14
Animals detect magnetic fields
  • Used for navigation by pigeons and other birds,
    honeybees, sea turtles, etc.

15
What happens when an animal that navigates using
magnetic fields has a magnet glued to its head?
16
Pit Vipers Detect Heat
  • Pits are located on head of pit viper
  • Pits contain receptor cells that can detect
    infrared radiation (heat)
  • A pit viper is able to see a fuzzy image of a
    warm object a pit viper can strike at a mouse in
    complete darkness.

17
Design an experiment to test if a pit is
actually sensing heat.
  • Is it possible the snakes pit is simply sensing
    the smell of another animal?
  • Hint Use a light bulb in your experimental
    set-up!

18
Elephants Detect Infrasounds
  • Infrasound sound too low to be heard by the
    human ear
  • Elephants call to each other with infrasound and
    stamp their feet which create sound waves that
    travel through earth.
  • Infrasound can travel exceptionally long
    distances.

19
Elephants Detect Infrasounds
  • It is hypothesized that this allows elephants to
    coordinate movement when they are miles apart.
  • Large elephant ears and feet (vibrations in
    ground) are the sense organs

20
Animals Detect Ultrasounds
  • Ultrasounds sounds too high to be heard by
    humans
  • Bats, dolphins, etc.

21
Design an experiment to test if bats actually use
ultrasounds for navigation
  • Hint Use cottonballs as part of your
    experimental set-up.

22
Aquatic Predators detect Electric Fields
  • Sharks (and others) can detect electrical
    activity in the muscles of passing prey.

23
Sharks and Aquarium
  • What problem might a shark have in a large tank
    in an aquarium?

24
Animals detect movement
  • An animals ear detects sound by the movement of
    sound waves through the air or water.
  • Mammals have bones in their middle ear that
    transmit the information carried in the sound
    waves to the brain.

25
Animals detect movement
  • This includes stimulus detected by the lateral
    line system in fish and other aquatic
    vertebrates.
  • This system detects movements and pressure
    changes in the surrounding water.

26
Animals and vision
  • Some animals can sense parts of the
    electromagnetic spectrum that are invisible to
    the human eye.

27
Human (and most vertebrate) Senses
  • Vertebrate eyes are camera eyes (vs. compound
    eyes of insects). Focuses incoming light onto a
    layer of photo-receptor cells on back of retina.

28
Vertebrate Eyes
  • Iris The colored diaphragm in the anterior
    chamber of the eyeball which contracts and
    expands to adjust for light intensity.
  • Pupil The opening in the center of the iris
    through which light passes.
  • Lens The transparent, dual-convex body which
    focuses light rays onto the retina. It is
    normally capable of changing shape to allow the
    eye to focus on both near and distant images.

29
Vertebrate Eye
  •  Retina Found on the back of the eye. Sensory
    cells contain light absorbing pigment (a molecule
    that absorbs only certain wavelengths of visible
    light and reflects or transmits other
    wavelengths)
  • cones color vision
  • rods light vision

30
Vertebrate Eye
  • The optic nerve attaches to retina and there are
    no photo-receptor cells at that location creating
    a blind spot.
  • Adaptations, such as the eye, (a characteristic
    that makes one individual more fit than another)
    do not have to be perfect.

Experiment with YOUR blind spot
31
Cats Eyes
  • A reflective layer behind the cat's retina called
    the tapetum reflects incoming light and bounces
    it back off the cones, making more use of the
    existing light.
  • The tapetum makes a cat's eyes look like shiny
    green orbs at night.

32
Vertebrates and Taste
  • Taste is a chemical sense perceived by
    specialized receptor cells that make up taste
    buds.
  • Flavor is a function of both taste and smell.

33
Vertebrates and Smell
  • Inside the nose is a big area called the nasal
    cavity.
  • On the roof of the nasal cavity are special
    sensory smell cells called olfactory receptor
    cells.

34
Vertebrates and Smell
  • Smells are in the form of a gas that is breathed
    in when animals inhale
  • The scent molecules in the gas pass by the
    olfactory receptor cells on the roof of the nasal
    cavity.
  • The smell cells send the signal up a nerve fiber
    to the brain.
  • This allows vertebrates to react quickly to
    smells.

35
Other Senses
  • Nociceptors Sense pain
  • Thermoreceptors Detect changes in temperature
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