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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 where they are processed and integrated. . Animal Senses.

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Animal senses
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.


Animal senses1
Animal Senses

  • Each type of animal is equipped with its own sensory receptors  each animal perceives its environment differently.


Animal senses2
Animal Senses

  • Animal senses are more varied and can be sharper than human senses.

  • Most sensory receptors are found on the head of an animal—the “head” is usually the first part of an animal to enter a new environment


Four basic modalities
Four Basic Modalities

  • Photoreception – response to light


Thermoreception
Thermoreception

  • Response to heat!


Mechanoreception
Mechanoreception

  • Response to movement.

  • This includes hearing, vibration, touch, balance, etc.

  • In vertebrates: air moves against bones in the ear. This movement is translated into “sound” by the brain.


Chemoreception
Chemoreception

  • Response to chemical energy, including smell and taste


Insect senses
Insect Senses

  • Compound eyes - made up of 100’s –1000’s 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 motion—the brain produces 1 detailed image.


Insect chemical receptors
Insect – Chemical Receptors

  • For taste and smell

  • Found on mouthparts, antennae and legs.

  • A fly’s foot can tell whether a liquid contains sugar or salt.


Sensory hairs
Sensory Hairs

  • Found mostly on head and legs

  • Can detect movement in surrounding air or water, and can detect certain chemicals.


Sensory hairs detect pheremones
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.


Pheremones
Pheremones

  • 1000 different insect pheremones known

  • Most are produced by females and are airborne.

  • Species specific sex attractants*.


Animal senses3
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.


Animals detect magnetic fields
Animals detect magnetic fields

  • Used for navigation by pigeons and other birds, honeybees, sea turtles, spiny lobsters, etc.


What happens when an animal which navigates using magnetic fields gets tricked
What happens when an animal which navigates using magnetic fields gets tricked?

  • Researchers at the University of NC, Chapel Hill, placed a large electric coil around a tub of water and generated a magnetic field.

  • They manipulated the field to fool the turtles into thinking they were more than 200 miles from home.

  • The turtles that “thought” they were 200 miles north of their home began to swim south.

  • The turtles that “thought” they were 200 miles south of their home began to swim north.


Pit vipers detect heat
Pit Vipers – Detect Heat fields gets tricked?

  • 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.


How do you test if a pit is actually sensing heat
How do you test if a “pit” is actually sensing heat? fields gets tricked?

  • Is it possible the snake’s pit is simply sensing the smell of another animal?


Elephants detect infrasounds
Elephants Detect Infrasounds fields gets tricked?

  • 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.


Elephants detect infrasounds1
Elephants Detect Infrasounds fields gets tricked?

  • 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*


Animals detect ultrasounds
Animals Detect Ultrasounds fields gets tricked?

  • Ultrasounds = sounds too high to be heard by humans

  • Bats, dolphins, etc.*



Aquatic predators detect electric fields
Aquatic Predators detect Electric Fields navigation?

  • Sharks (and others) can detect electrical activity in the muscles of passing prey.


Sharks and aquarium
Sharks and Aquarium navigation?

  • What problem might a shark have in a large tank in an aquarium?


Animals detect movement
Animals detect movement navigation?

  • An animal’s 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.


Animals detect movement1
Animals detect movement navigation?

  • 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.


Animals and vision
Animals and vision navigation?

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

*


Human and most vertebrate senses
Human (and most vertebrate) Senses navigation?

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


Vertebrate eyes
Vertebrate Eyes navigation?

  • 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.


Vertebrate eye
Vertebrate Eye navigation?

  • 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


Vertebrate eye1
Vertebrate Eye navigation?

  • 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


Cat s eyes
Cat’s Eyes navigation?

  • 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.


Vertebrates and taste
Vertebrates and Taste navigation?

  • Taste is a chemical sense perceived by specialized receptor cells that make up taste buds.

  • Flavor is a function of both taste and smell.


Vertebrates and smell
Vertebrates and Smell navigation?

  • 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.”


Vertebrates and smell1
Vertebrates and Smell navigation?

  • 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.


Other senses
Other Senses navigation?

  • Nociceptors – Sense pain

  • Thermoreceptors – Detect changes in temperature


Animal vs human senses
Animal vs. Human Senses navigation?

  • The Savannah

*


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