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Environmental Sciences
ENVS 2210
Ernesto Guzman

ENVS Unit 07 pages 191-223 Senses: Bees’ Perceptions of the World - Honeybees brain 850 000 cells, gets info from sensory array - Five eyes have photoreceptive tasks, the ocelli are little more than light metres - Compound eyes need bright light to gather info on images: colour, colour patterns, sizes, shapes, symmetries, edges, and movements - Compound eyes have tiny facets of compound that can receive three wavelengths: ultraviolet, blue, green - Sense polarization of daylight - Smell and taste = chemical sense o Most tasting done in mouthparts but antenna can taste as well as smell - Sensillae are microscopic sensors - Several generic types respond to types of stimuli: chemicals, touch, heat, humidity, carbon dioxide, vibration o Senses of touch and vibration mediated by mechanoreceptors - Proprioception: providing info to central nervous system about relative body parts - Bees can tell and measure time - Bees sensitive to magnetism and electricity, but we don’t know how Vision and Light - Light sensed in diff ways: o Presence )above certain threshold) or absence (below that threshold) o Discrim. Of wavelengths, repped by colour vision o Disc. Of images (shapes and sizes) through sharpness of vision o Polarization angle that light rays diff pass through a medium (usually air or water) o Speed of reaction of optical sensors that allow for sensing movement - 3 simple eyes (ocelli) in honeybee located top of head, can monitor light intensity, period of exposure to light, and wavelength o Each had one lens for the entire retina and can refract to about 800 photoreceptor cells - Camera eye (human beings)- light enters eye through cornea and aqueous humour, goes through lens etc. to retina and ya o Rod and cone cells, trichromatic receptors very exiting o Visual pigments: rhodopsin and iodopsin, breaks down pigment cell and excited nerve cell, nerve impulses go to dendrites to axons to brain o Colour is visual perception associated w/ various wavelengths in visible portion of electromagnetic spectrum of light o Red green and blue are the primary colours (trichromatic), achromatic vision = no colour (nocturnal animals) o Honeybees and all insects have two compound eyes that has many facets, like a mosaic, large picture of relatively small tiles so total picture cant be seen  Ability to see detail is resolving power  Depending on colour, object of that size isn’t recognized by honeybee until about 1 metre or less from it (196) - Light enters through each facet of honeybee through corneal le
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