Vision Through the Colored Eyes of the Horse fly - Haematopota pluvialis

The conspicuous eye-color patterns of tabanid flies have been frequently portrayed. The eye colors originate from cornea color filters, which, on the one hand, cause colorful reflections and, on the other, alter the spectral composition of transmitted light.

The green/orange eyes of female Haematopota pluvialis (Diptera - Tabanidae) have four horizontal irregular dark brown stripes. The green/orange eye regions consist of a number of facets almost equal to the dark brown eye regions. Intermediate areas of red facets are small in extension. The spatial pattern of males is female-like, but reduced in size, and shifted to the ventral half of the compound eye. 

It has been hypothesized that the external appearance of compound eyes, caused by the colorful reflections from the facets, serves as an intraspecific communication signal. And also the flies could benefit from the wavelength-specific, reduced transmission in terms of an improved perception of visual signals.

Reference: [1]

Photo credits: [Top: ©Lukas Jonaitis | Locality: Lithuania, 2011] - [Bottom: ©Eddie The Bugman | Locality: Willford, England, United Kingdom, 2014] 

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Haematococcus pluvialis is a freshwater species of Chlorophyta from the family Haematococcaceae. This species is well known for its high content of the strong antioxidant astaxanthin, that is important in aquaculture, various pharmaceuticals and cosmetics. The high amount of astaxanthin is present in the resting cells, which are produced and rapidly accumulated when the environmental conditions becomes unfavorable for normal cell growth. Examples of such conditions are i.e. high light, high salinity or low nutrients. Haematococcus pluvialis is usually found in temperate regions around the world. Their resting cysts are often responsible for the blood-red colour seen in the bottom of dried out rock pools and bird baths. This colour is caused by astaxanthin which is believed to protect the resting cysts from the detrimental effect of UV-radiation, when exposed to direct sunlight.

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Black-bellied Plover ~ Kiebitzregenpfeifer ~ Pluvialis squatarola

It is an interesting experience when the bird you are taking pictures of falls asleep in the middle of it. :-D (And pssst … Have a look at those eyelashes! :-)

Sanibel Island, Florida, USA

2014 © Jesse Alveo