BIOLOGY Egypt in Context. Cairo, Egypt:The American Visual Perception in Humans and Jumping Spiders -ican Association for the advancement of A Comparative Study Joseph Donovan Abstract She wrote this paper for ANTH-P398 with There are many animals that are highly dependent upon vision for survival. Primates are a prime rnderVeen. example of this. As primates, we use vision in almost every aspect of our lives and our visual system has become highly evolved to accommodate this. We have the ability to perceive depth, detail, motion, color, scenes, and objects of all kinds. We can focus on any aspect of our environment at any time. But many other animals have these abilities too. A jumping spider is another prime example of an animal that is highly dependent upon vision for survival. As such, their visual system has also become highly evolved and is rather unique for an invertebrate. In a sense, the primary eyes of a jumping spider are very much like the eyes of a primate. They are capable of color vision, object discrimination, and, unlike many other arthropods, have a type of foveal system. Introduction ll jumping spiders are representatives of the family Salticidae. Salticidae is the largest A family of spiders and representatives inhabit every continent except Antarctica. Their visual system is composed of eight eyes separated into three or four rows (Ubick, 2005, pg. 205). It has been demonstrated that the primary role of the lateral eye rows is to detect motion and orient the spider to face the moving object so that its image falls on the retina of the anterior medial eyes (Devoe, 1975, pg.203). In jumping spiders, the anterior medial eyes are enlarged and serve as the primary eyes. Like the eyes of humans, these eyes are frontal eyes and are capable of binocular vision. They are used in locomotion, hunting, and the intraspecific communication of courtship and agonistic displays, all of which are very important to the spider' s survival and reproduction. Experiments on these eyes have demonstrated that the spiders could effectively perform vision dependent behaviors with all eyes except the primary eyes covered. However, they could not perform these behaviors with only the primary eyes covered. In this paper, lam going to compare the visual system of a human with that of a jumping spider. I am going to explain that, while there are many differences between the two visual systems, there are also some surprising similarities that allow the two animals to effectively survive in their respective environments. 13 BIOLOGY Color Vision Like humans, jumping spider can potentially percei In terms of their capabilities, the primary eyes of jumping spiders are fairly impressive. humans, the anterior-medial eyes of jumping spide1 Experiments involving intracellular recording from jumping spider retinal cells have demonstrated ultraviolet portion of the spectrum. However, just t that these spiders have the possibility, at the very least, for dichromatic vision, with cells vision does not mean that jumping spiders perceive responding to wavelengths corresponding to the green and ultraviolet portions of the spectrum assume this would be anthropomorphic and errone• (Devoe, 1975, pg.193). The possibility for retinal cells that respond to blue and red light has been evolved along considerably different lines. In fact, under some dispute but it is currently thought that jumping spider vision is tetrachromatic, as types of eyes. Many can be seen by looking at the < opposed to trichromatic vision in the humans (Peaslee, 1989, pg.359). This would allow jumping regardless of these differences, there are still some spiders to see all colors in the visible spectrum as well as the ultraviolet portion of the electromagnetic spectrum. This means that these spiders would be able to see all the colors that Form Vision, Eye Structure, and Eye Mov{ humans can and color that humans cannot. In addition to color vision, the anterior medial eye: However, just because ultraviolet visual cells exist in the spider's retina does not necessarily mean that is comparable to human vision. In a research a that these spiders can see in the ultraviolet spectrum. This is why behavioral studies have been spiders, it was proposed that the jumping spider e) done to demonstrate that the spiders experience ultraviolet as a color. One experiment studied the form vision in the animal kingdom. With the anter relationship between ultraviolet cues in potential prey and the spider's response to that particular found to be able to distinguish between the forms ' prey. Many insects reflect ultraviolet light while bark, leaves, and soil do not (Li, 2005a, pg. 771). of at least ten body lengths (Land, l 969b, pg. 4 71 ) This may help the spiders discriminate a food item from its background. Also, many spider-webs of the eye and used new opthalmoscopic techniqm contain ultraviolet cues. It was found that the jumping spider Portia labia/a could discriminate to the location and identification of objects in thei1 between an orb-web that reflected ultraviolet light and one that did not. They preferentially hunted The structure of the anterior-medial eyes in jumpir the spiders whose webs reflected ultraviolet light over the spiders whose webs did not reflect this many ways. In humans the whole optical system rr part of the spectrum (Li, 2005a pg.774). In this way, ultraviolet signals can serve as foraging cues corneas are a fixed part of the carapace and do not for jumping spiders in much the same way that the color of fruit can serve as a foraging cue for humans, the retina lines the rear inner surface oftl humans (Goldstein, 2007, pg.203). are located at the bottom of an elongated eye tube. together, form the shape of a diagonal cross. Like Other behavioral evidence that jumping spiders can see ultraviolet can be found by examining the muscles. In jumping spiders, these six muscles wo differences between males and females. In a study done in 2005, it was found that jumping spiders displaces the retina. Four muscles are attached to I are sexually dimorphic in their reflectance of ultraviolet. Males reflected ultraviolet light on many eye tube up to down and left to right. The two rerr parts of their bodies whereas juveniles and females did not. When ultraviolet cues were eliminated tube and retina (Land, J969b, pg.492). This make from a male jumping spider, other males would be less likely to engage in competition and mobility to the human eye. A major difference bet agoni stic displays with that male (Li, 2005b, pg.402). Also, when the ultraviolet cues were of the eyes. In humans, there is only a single lens. removed from a male spider that was shown its own reflection, the male would attempt to perform a fixed to the carapace. The second is at the rear of courtship display with its own mirror image (Li, 2006, pg. 871). This makes sense because females second lens acts to increase the magnifying power do not reflect ultraviolet light and presenting the spider with its mirror image devoid of ultraviolet elongated, causes the eye to function very much Ii humans, the shape of lens changes through the ac1 signals would trick the spider into thinking its own reflection ~as a female jumping spider. In this way, ultraviolet cues on the bodies of male jumping spiders serve as sexual signals used for accommodation and the shape change of the lens discriminating between the sexes, initiating courtship displays, and eliciting agonistic behavior In spiders, there is no known mechanism for acco between males. This behavioral evidence supports the idea that jumping spiders can perceive color forwards or backwards to adjust for focal length. 1 in the ultraviolet spectrum. 14 BIOLOGY Like humans, jumping spider can potentially perceive the full range of the visible spectrum. Unlike mping spiders are fairly impressive. humans, the anterior-medial eyes of jumping spiders are capable of perceiving color in the jumping spider retinal cells have demonstrated ultraviolet portion of the spectrum. H?wever, just because this pair of eyes is capable of color ast, for dichromatic vision, with cells vision does not mean that jumping spiders perceive color in the same way that humans do. To :en and ultraviolet portions of the spectrum assume this would be anthropomorphic and erroneous considering that spiders and humans have ells that respond to blue and red light has been evolved along considerably different lines. In fact, there are many differences between the two umping spider vision is tetrachromatic, as types of eyes. Many can be seen by looking at the differences in structure between the two. Yet lee, 1989, pg.359). This would allow jumping regardless of these differences, there are still some striking similarities. rell as the ultraviolet portion of the iders would be able to see all the colors that Form Vision, Eye Structure, and Eye Movements ln addition to color vision, the anterior medial eyes of the jumping spiders have another capability in the spider' s retina does not necessarily mean that is comparable to human vision. In a research article about the eye movements in jumping 1. This is why behavioral studies have been spiders, it was proposed that the jumping spider eye represents one of the simplest cases of true :aviolet as a color. One experiment studied the form vision in the animal kingdom. With the anterior medial eyes, jumping spiders have been ·ey and the spider' s response to that particular found to be able to distinguish between the forms of potential prey and potential mates at distances rk, leaves, and soil do not (Li, 2005a, pg. 771). of at least ten body lengths (Land, 1969b, pg.