Presentation Title

Response of Body Morphometrics and Eye Development in the Crayfish Cambarellus patzcuarensis to Differing Light Wavelengths Experienced During Juvenile Life

Format of Presentation

Poster to be presented Friday March 31, 2017

Abstract

Many environmental factors, such as light, can affect the development of an organism. Examples of altered development in differing light conditions have been seen across many crayfish species. A notable case of varying development is seen in the eye of crayfish species that have high light exposure living in shallow springs compared to those living in habitats of low light exposure such as caves. This project aimed to investigate the effects of exposure to certain wavelengths of light on the development and morphology of the eye and exoskeleton in the Orange Dwarf Crayfish, Cambarellus patzcuarensis. This was done by exposing juvenile crayfish to a single light quality (red, blue, white, or no light) for a period of two months, which is the time required to reach the adult life stage. This experiment was carried out for two generations of crayfish. Upon maturation, body size and exoskeleton colouration were quantified through digital photographs. In addition, properties of the eye surface and internal eye features were examined through scanning electron microscopy and light microscopy, respectively. Although crayfish body size varied at the time of sampling, growth did not appear to be stunted under any particular wavelength. In all individuals, the density of the ommatidia (individual eye cell units) was uniform. Variation, though irrespective of the light quality, was seen in ommatidia size and eye area. Exoskeleton colouration was brighter in individuals from the “no light” treatment, suggesting that less pigments are produced when individuals develop in darkness.

Department

Biological Sciences

Faculty Advisor

Dr. Louis Gosselin

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Response of Body Morphometrics and Eye Development in the Crayfish Cambarellus patzcuarensis to Differing Light Wavelengths Experienced During Juvenile Life

Many environmental factors, such as light, can affect the development of an organism. Examples of altered development in differing light conditions have been seen across many crayfish species. A notable case of varying development is seen in the eye of crayfish species that have high light exposure living in shallow springs compared to those living in habitats of low light exposure such as caves. This project aimed to investigate the effects of exposure to certain wavelengths of light on the development and morphology of the eye and exoskeleton in the Orange Dwarf Crayfish, Cambarellus patzcuarensis. This was done by exposing juvenile crayfish to a single light quality (red, blue, white, or no light) for a period of two months, which is the time required to reach the adult life stage. This experiment was carried out for two generations of crayfish. Upon maturation, body size and exoskeleton colouration were quantified through digital photographs. In addition, properties of the eye surface and internal eye features were examined through scanning electron microscopy and light microscopy, respectively. Although crayfish body size varied at the time of sampling, growth did not appear to be stunted under any particular wavelength. In all individuals, the density of the ommatidia (individual eye cell units) was uniform. Variation, though irrespective of the light quality, was seen in ommatidia size and eye area. Exoskeleton colouration was brighter in individuals from the “no light” treatment, suggesting that less pigments are produced when individuals develop in darkness.