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. 471 ). In light of this, researchers studied the structure from its background. Also, many spider-webs of the eye and used new opthalmoscopic techniques to track the movements of the retina in relation ing spider Portia labiata could discriminate to the location and identification of objects in their field of view. md one that did not. They preferentially hunted The structure of the anterior-medial eyes in jumping spiders differs from that of the human eye in ver the spiders whose webs did not reflect this many ways. In humans the whole optical system moves, whereas in jumping spiders, the lenses and r, ultraviolet signals can serve as foraging cues corneas are a fixed part of the carapace and do not move with the retina (Land, 1969b, pg. 478). In color of fruit can serve as a foraging cue for humans, the retina lines the rear inner surface of the eye whereas, in jumping spiders, the retinas are located at the bottom of an elongated eye tube. They are shaped like bent canoes and, taken together, form the shape of a diagonal cross. Like humans, each eye is moved by a series of six

1 see ultraviolet can be found by examining the muscles. In jumping spiders, these six muscles work together to move the elongated eye tube which fone in 2005, it was found that jumping spiders displaces the retina. Four muscles are attached to the carapace and work together to displace the ·iolet. Males reflected ultraviolet light on many eye tube up to down and left to right. The two remaining muscles work together to rotate the eye did not. When ultraviolet cues were eliminated tube and retina (Land, I 969b, pg.492). This makes the jumping spider eye similar in its degree of less likely to engage in competition and mobility to the human eye. A major difference between to the two types of eyes involves the lenses 2). Also, when the ultraviolet cues were of the eyes. In humans, there is only a single lens. In jumping spiders, there are two lenses. One is n reflection, the male would attempt to perform a fixed to the carapace. The second is at the rear of the eye tube just in front of the retina. This 106, pg. 871 ). This makes sense because females second lens acts to increase the magnifying power of the original lens and, because the eye tube is 1ider with its mirror image devoid of ultraviolet elongated, causes the eye to function very much like a telescope (Richman, 1992, pg.33). In reflection was a female jumping spider. In this humans, the shape oflens changes through the action of the ciliary muscle. The process is called

~ spiders serve as sexual signals used for accommodation and the shape change of the lens puts an image into focus on the back of the retina. 1ip displays, and eliciting agonistic behavior In spiders, there is no known mechanism for accommodation and the eye tube cannot move the idea that jumping spiders can perceive color forwards or backwards to adjust for focal length. (Richman, 1992, pg.33)

15 BIOLOGY

In jumping spiders, four kinds of eye movement activity have been distinguished using Bibliography opthalmoscopic techniques (Land, 1969b, pg. 478). These types of eye movement included spontaneous activity, saccades, tracking, and scanning. Spontaneous activity consisted of rapid Devoe, Robert. "Ultraviolet and Gree periodic side-to-side movement and typically occurred when the spider was in a state of high Spiders" The Journal of General Physiology Ve excitability. Saccades occurred when a stimulus was presented to the retinas of the anterior medial or lateral eyes and involved movement of the retinas so that the image of the stimulus came to rest Goldstein, Bruce. Sensation and Perco on the central portion of both retinas. Tracking occurred when a moving target was followed by the Wadsworth (California) 459 pages; 2007 retinas. Scanning typically followed a saccade and involved the side-to-side movement of the retinas across a stimulus (Land, l 969b, pg. 492). These patterns of eye movements are similar to Land, M.F. "Structure of the Retinae human eye movements in the sense that when the human eye is presented a novel stimulus it will Relation to Visual Optics" Journal ofExperime make a saccade from its point of fixation to the stimulus. This causes the image of the stimulus to 10, 1969a be presented on the fovea. The fovea is a part of the retina that is composed entirely of cones. The foveae of both eyes are used to perceive the details ofa stimulus. If the stimulus is moved, the eye Land, M.F. "Movements of the Retin: will track the stimulus with the fovea and, like scanning activity in jumping spiders, the human eye Stimuli" Journal of Experimental Biology Volu will scan the object. The human eye does this to perceptually integrate the various parts of the stimulus. The same appears to be true of jumping spiders. When a moving object is displayed to the Li, Daiqin; Lim, Matthew. "Ultraviol0 peripheral retinas of a jumping spider, the eye tubes will move to bring the image of the object onto Spiders" Animal Behavior Volume 70, pages 7' the central portion of retinas, which has four layers of receptors as opposed to two in the periphery. Essentially what this means is that, like the eyes of humans and unlike the eyes of most arthropods Li , Daiqin; Lim, Matthew. "Extreme and amphibians, the jumping spider eye is organized into a type of foveal system that is used to Biological Journal of the Linnean Society Volu evaluate the details ofa stimulus (Land, 1969b, pg. 488). Li , Daiqin; Lim, Matthew. "Behavior Conclusion Journal of Comparative Physiology Volume 19

The anterior medial eyes of the jumping spiders have many differences and similarities to the eyes Peaslee, Alan; Wilson, Graeme. "Spe of humans. Like humans, their frontal eyes are capable of distinguishing form and color and are Comparative Physiology Volume 164, Number organized into a type of foveal system, which makes their eyes unique amongst arthropods. Both types of eyes are moved by a series of six muscles and both have high acuity. Both represent a case Richman, David; Jackson, Robert. "A of true form vision, contain lenses, and display similarities in patterns of eye movement. However, Bulletin of the British Arachnological Society' unlike the human eye, the jumping spider eye contains two lenses, has no accommodation mechanism, and has the ability to see color in the ultraviolet portion of the spectrum. The eyes of Ubick, D., P. Paquin; P.E. Cushing,~ these spiders are also shaped and structured much differently from the human eye because they are identification manual An1erican Arachnologica elongated and have retinas only at the end of the eye tube as opposed to lining the inside of the eye. In conclusion, there are many differences and similarities between the visual systems of humans and jumping spiders, but both cases represent animals that have highly evolved visual systems and Joseph is a senior majoring in Biology. He w1 are highly dependent upon these systems for survival and performing common, everyday tasks. and Per'

16 BIOLOGY activity have been distinguished using Bibliography '8). These types of eye movement included nning. Spontaneous activity consisted of rapid Devoe, Robert. "Ultraviolet and Green Receptors in the Principal Eyes of Jumping

~urred when the spider was in a state of high Spiders" The Journal of General Physiology Volume 66, pages 193-207; August I, 1975 was presented to the retinas of the anterior medial inas so that the image of the stimulus came to rest Goldstein, Bruce. Sensation and Perception: Eight Edition Cengage Learning, •ccurred when a moving target was followed by the Wadsworth (California) 459 pages; 2007 1d involved the side-to-side movement of the These patterns of eye movements are similar to Land, M.F. "Structure of the Retinae of the Principal Eyes of Jumping Spiders in

~human eye is presented a novel stimulus it will Relation to Visual Optics" Journal of Experimental Biology Volume 51 , pages 443-470; February timulus. This causes the image of the stimulus to 10, 1969a the retina that is composed entirely of cones. The ils ofa stimulus. lfthe stimulus is moved, the eye Land, M.F. "Movements of the Retinae of Jumping Spiders in Response to Visual :anning activity in jumping spiders, the human eye Stimuli" Journal of Experimental Biology Volume 51 , pages 4 71-493; February I 0, I 969b perceptually integrate the various parts of the

~ spiders. When a moving object is displayed to the Li, Daiqin; Lim, Matthew. "Ultraviolet Cues Affect the Foraging Behavior of Jumping bes will move to bring the image of the object onto Spiders" Animal Behavior Volume 70, pages 771-776; August 18 , 2005a :rs of receptors as opposed to two in the periphery. of humans and unlike the eyes of most arthropods Li , Daiqin; Lim, Matthew. "Extreme Ultraviolet Sexual Dimorphism in Jumping Spiders" ized into a type of foveal system that is used to Biological Journal of the Linnean Society Volume 89, pages 397-406; October 4, 2005b Jg. 488). Li, Daiqin; Lim, Matthew. "Behavioral Evidence of UV Sensitivity in Jumping Spiders" Journal of Comparative Physiology Volume 192, pages 871-878; April 7, 2006 have many differences and similarities to the eyes Peaslee, Alan; Wilson, Graeme. "Spectral Sensitivity in Jumping Spiders" Journal of 1pable of distinguishing form and color and are Comparative Physiology Volume 164, Number 3, pages 359-363; May, 1989 1kes their eyes unique amongst arthropods. Both :sand both have high acuity. Both represent a case Richman, David; Jackson, Robert. "A Review of the Ethology of Jumping Spiders" imilarities in patterns of eye movement. However, Bulletin of the British Arachnological Society Volume 9(2), pages 33-37; 1992 ntains two lenses, has no accommodation : ultraviolet portion of the spectrum. The eyes of Ubick, D. , P. Paquin; P.E. Cushing, and V. Roth. Spiders ofNorth America - an h differently from the human eye because they are identification manual American Arachnological Society, Keene (New Hampshire). 377 pages; 2005 eye tube as opposed to lining the inside of the eye. nilarities between the visual systems of humans imals that have highly evolved visual systems and Joseph is a senior majoring in Biology. He wrote this paper for Dr. Scheessele's P329 Sensation 1ival and performing common, everyday tasks. and Perception class.

17