Correlation between Histological and Behavioral Measures of Visual Acuity in a Zooplanktivorous Fish, the White Crappie <i>(Pomoxis annularis)</i>

Abstract

Estimates of visual acuity in a pelagic freshwater zooplanktivorous fish, the white crappie (Pomoxis annularis, Centrarchidae), were made using a behavioral measure, the maximum observed prey pursuit distance (MxPD), and a histological measure, the density of cone cells in the retina. The greatest number of pursuits occurs in the 0–30° wedge of the visual field; 87% of all pursuits occur in the first 40°. The longest pursuits (200 mm) also occur in this area and generally get shorter from 0 to 180° (from forward-directed) in the visual field. Consistent with the behavioral results, the largest number of cone photoreceptors (13,000/mm²) is found in the far temporal retina along the eye's horizontal meridian. Cone cell densities in the corresponding region of the nasal retina are approximately half this value. The number of cones decreases dorsally and ventrally from the horizontal meridian. Although the absolute values of visual acuity calculated from cone cell topography (i.e. MxPDs of 500 mm) are 2–3 times greater than those observed behaviorally (i.e. MxPDs of 200 mm), the trends in visual acuity across the visual field obtained from both measures are consistent. We suggest that overestimates of visual acuity obtained from cone cell counts alone result from this measure's not accounting for, among other properties of the nervous system, cone cell convergence onto ganglion cells and higher brain centers. Behavioral measures of visual acuity are, therefore, likely to yield a more accurate estimate of an animal's visual abilities.

Vision in the grass goby,Zosterisessor ophiocephalus(Teleostei, Gobiidae): A morphological and behavioural study

“…In Z. ophiocephalus, the calculated histological visual acuity was better than the behavioural one, as reported in other fish species (review in Douglas & Hawryshyn, 1990;Browman et al, 1990;van der Meer, 1995;Wanzenbock et al, 1996). Estimates of visual acuity based upon inter-cone spacing could be higher than those observed behaviourally because counts of cell density alone do not take signal convergence and processing into account (Browman et al, 1990).…”

“…For a prey target of known size at a given distance from the eye, this visual angle in degrees is calculated as (Hairston et al, 1982;Browman et al, 1990):…”

“…In most fish species, a region with a higher cell density called area centralis is present. The distribution of different cell densities, or retinal topography, was studied by analysing the cone density or cell density in the layer of ganglion cells (reviews in Browman et al, 1990;Beaudet et al, 1997;Collin, 1997). The studies show that the shape and position of the area centralis differ among the species and depend on their foraging ecology.…”

“…The more cells covered by the image, the better is its resolution (Tamura, 1957). In teleosts, visual acuity has been determined by histological, electrophysiological and behavioural measures (reviews in Collin & Pettigrew, 1989;Douglas & Hawrhyshyn, 1990;Browman et al, 1990;Wanzenbock et al, 1996). The differences in visual acuity found among the species are due to feeding ecology: a lower visual acuity was calculated in herbivorous and nocturnal species of fish, while a higher acuity was calculated in predatory and piscivorous fish.…”

Vision in the southern hemisphere lampreyMordacia mordax: Spatial distribution, spectral absorption characteristics, and optical sensitivity of a single class of retinal photoreceptor

“…The estimate of spatial resolving power (1.7 cycles0deg) and minimum separable angle (34 ' 7 '' ), based on photoreceptor spacing, is lower than in teleosts such as the white crappie Pomoxis annularis (7 ' 0 '' , Browman et al, 1990), the convict fish Microcanthus strigatus (3 ' 36 '' , Yamanouchi, 1956;Nakamura, 1968), the bluegill sunfish Lepomis macrochirus (2 ' 42 '' , Williamson & Keast, 1988), the cichlid Haplochromis argens (11 ' , van der Meer, 1995), and a range of marine species examined by Tamura (1957) who found acuities from 4 ' 12 '' to 15 ' 24 '' . Considering that there is often an appreciable convergence of information onto the output or ganglion cells and that behavioral acuity is constrained by their spacing (Collin & Pettigrew, 1989), the spatial resolution of M. mordax may be even less.…”