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If you're a new hamster owner, you may have--literally--lost sleep over the question "can hamsters see in the dark?" Nocturnal creatures like hamsters spend most of their waking hours in low light conditions, so deciphering how their eyesight works is an important topic. In this article, we'll cover the specifics of hamster vision so you can learn more about how your pet views the world. How Your Hamster's Eyes Work Similar to other mammals, hamsters see the world through eyes consisting of a variety of parts. Their eyes function by allowing light to enter through the cornea, a transparent layer surrounding the eye that permits both visible and ultraviolet light. The light then reaches the round opening called the pupil, which controls the amount of light entering the eye based on the level of brightness. After the pupil, light passes through the lens, which filters some light and adjusts the focus. Finally, the light passes through the vitreous body, a gel-like substance, and is focused on the retina. The retina, located at the rear of the eyeball, transforms light energy into electrical signals that are sent to the brain via the optic nerve. The retina is composed of two types of cells: rods and cones. The Eyes of Hamsters Hamster eyes are basically spherical, and they can be found in various colors, ranging from pink to black. The appearance of their eyes depends on their species. The eyes of rodents include the same parts as the human eye, like the iris, pupil, lens, retina, and the optic nerve. However, in hamsters, the lens cannot change shape like it can in humans because it is fixed. The pupil is also a more obvious part of the eye. Additionally, hamsters have a panoramic visual field that is binocular which provides them with the ability to have excellent perception of depth. What do Hamsters See? A hamster's visual system is not well-developed when it is born. In fact, it is completely blind and photophobic. This means that they feel sensitive, like discomfort, around the eyes when exposed to light. Their overall eyesight is poor, particularly in bright light conditions. Hamsters have a smaller number of cones which allow them to see color and provide general visual acuity, and mostly rod cells. Cones are light-sensitive protein pigments that give humans the ability to see color and make out shapes in different areas of space, but hamsters see things much differently than humans do. Rod cells are responsible for letting us see in low light conditions, which is why hamsters can see better with less light. Hamsters use their vision to investigate their food and catch insects, and they also use visual social symbols for aggression. They respond to high levels of light by ceasing activity. Because of their poor eyesight, they rely more on their other senses such as hearing, taste, and smell for perception. Can Hamsters See in the Dark? Hamsters can't see in complete darkness, as light is still required to detect objects. In general, hamsters see best in dim light, such as at dawn and dusk. They can detect objects best in low-light circumstances. There is currently no evidence to suggest that Syrian hamsters have different levels of night vision beyond normal hamsters. Due to their weak eyesight, hamsters usually rely on their other senses. Hamsters have oversized teeth and whiskers that enable them to use their senses in the absence of good vision. Do Hamsters See in Color? It's hard to come up with an exact answer to this question, as the number of cones an animal has and how the brain processes information makes determining what colors animals are capable of seeing difficult. However, studies have shown that Syrian hamsters are basically monochromatic. Simply put, they see all colors as one color. In the same way, blue and green stimuli showed up in some rodent vision tests, suggesting that hamsters might detect these colors to some extent. Scientists have discovered that hamsters can see ultraviolet light through photopigments other than rhodopsin. The ability for hamsters to see UV light could aid them in navigating around during the day and twilight hours. Hamster Vision While hamsters have weak eyesight overall, they are able to compensate for this weakness with additional senses. They are best at detecting objects under dim lighting conditions, which is believed to be a result of adaptation to being most active at dawn and dusk. They have excellent depth perception due to their binocular visual field, but the world they perceive is mostly black and white with a range of green. While they see the world differently than humans, it's still fascinating to understand how they perceive their surroundings. So, take a closer look at your hamster's eye and see if you notice the parts described in this article. Does your hamster get nervous when something approaches it? Do you believe it can see any other colors than green or blue? Share your observations in the comments section below. Resources and Further Reading Brainard, G. C. et al (2001), “Influence of near-ultraviolet radiation on reproductive and immunological development in juvenile male Siberian hamsters,” The Journal of Experimental Biology, Vol. 224, 2535-2541. Calderone, J.B., and Jacobs, G.H.(1999), “Cone receptor variations and their functional consequences in two species of hamster,” Visual Neuroscience, 16(1), 53-63. Clive Roots, Nocturnal Animals (2006), Greenwood Publishing Group. Emerson, V. F. (1980), “Grating acuity of the golden hamster. The effects of stimulus orientation and luminance,” Experimental Brain Research, VOl. 38(1), 43-52. Finlay, B. & Berian, C. A. Barbara Finlay, “Visual and Somatosensory Processes” in Harold Siegel (ed.) (2012), The Hamster, Reproduction and Behavior, Springer Science & Business Media. Hanson, A. (2006), “What do rats see?” Rat Behavior, . Von Schantz, M., et al, (1997), “Photopigments and photoentrainment in the Syrian golden hamster,” Brain Research, Vol. 770, 131-138. “Exhibition Standards,” (2016), National Hamster Council.

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