Premium
Photoreceptor types, visual pigments, and topographic specializations in the retinas of hydrophiid sea snakes
Author(s) -
Hart Nathan S.,
Coimbra João Paulo,
Collin Shaun P.,
Westhoff Guido
Publication year - 2012
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.22784
Subject(s) - biology , visual pigments , retina , foraging , anatomy , retinal , rhodopsin , ecology , neuroscience , botany
Sea snakes have evolved numerous anatomical, physiological, and behavioral adaptations to suit their wholly aquatic lifestyle. However, although sea snakes use vision for foraging and mate selection, little is known about their visual abilities. We used microspectrophotometry, light microscopy, and scanning electron microscopy to characterize the retinal photoreceptors of spine‐bellied ( Lapemis curtus ) and horned ( Acalyptophis peronii ) sea snakes. Both species have three types of visual pigment sensitive to short (SWS; wavelength of maximum absorbance, λ max 428–430 nm), medium (MWS; λ max 496 nm), and long wavelengths of light (LWS; λ max 555–559 nm) in each of three different subtypes of cone‐like single photoreceptor. They also possess a cone‐like double photoreceptor subtype, both the principal and accessory member of which contain the LWS visual pigment. Conventional rods were not observed, although the MWS photoreceptor may be a “transmuted” rod. We also used stereology to measure the total number and topographic distribution of neurons in the ganglion cell layer of L. curtus , the olive sea snake ( Aipysurus laevis ), and the olive‐headed sea snake ( Disteira major ). All species have a horizontal visual streak with specialized areas in the nasal and temporal retina. Both L. curtus and D. major also have a specialized area in the ventral retina, which may reflect differences in habitat usage and/or foraging behavior compared to A. laevis . Maximal spatial resolution was estimated at 1.1, 1.6, and 2.3 cycles deg −1 in D. major, L. curtus , and A. laevis , respectively; the superior value for A. laevis may reflect its specialized crevice‐foraging hunting technique. J. Comp. Neurol. 520:1246–1261, 2012. © 2011 Wiley Periodicals, Inc.