Document Detail

Color discrimination at the spatial resolution limit in a swallowtail butterfly, Papilio xuthus.
MedLine Citation:
PMID:  16857870     Owner:  NLM     Status:  MEDLINE    
Spatial resolution of insect compound eyes is much coarser than that of humans: a single pixel of the human visual system covers about 0.008 degrees whereas that of diurnal insects is typically about 1.0 degrees . Anatomically, the pixels correspond to single cone outer segments in humans and to single rhabdoms in insects. Although an outer segment and a rhabdom are equivalent organelles containing visual pigment molecules, they are strikingly different in spectral terms. The cone outer segment is the photoreceptor cell part that expresses a single type of visual pigment, and is therefore monochromatic. On the other hand, a rhabdom is composed of several photoreceptor cells with different spectral sensitivities and is therefore polychromatic. The polychromatic organization of the rhabdom suggests that insects can resolve wavelength information in a single pixel, which is an ability that humans do not have. We first trained the Japanese yellow swallowtail butterfly Papilio xuthus to feed on sucrose solution at a paper disk of certain color. We then let the trained butterflies discriminate disks of the training color and grey disks each presented in a Y-maze apparatus. Papilio correctly selected the colored disk when the visual angle was greater than 1.18 degrees for blue, 1.53 degrees for green or 0.96 degrees for red: they appeared to see colors in single pixels to some extent. This ability may compensate their rather low spatial resolution.
Yuichi Takeuchi; Kentaro Arikawa; Michiyo Kinoshita
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of experimental biology     Volume:  209     ISSN:  0022-0949     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  2006 Aug 
Date Detail:
Created Date:  2006-07-21     Completed Date:  2006-10-04     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  2873-9     Citation Subset:  IM    
School of Advanced Sciences, The Graduate University for Advanced Studies, Hayama 240-0193, Japan.
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MeSH Terms
Butterflies / physiology*
Color Perception / physiology*

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