Biological Sciences
Presenter(s): Dahlya Habashi
Advisor(s): Dr. Douglas Fudge
Hagfishes are marine craniates that burrow into the ocean floor. Hagfishes do not have functional eyes, instead, they have unpigmented eye spots located on the top of their head. As such, hagfishes perceive light through a dermal light sense, photoreceptors under the skin. Though effectively blind, Pacific hagfish (Eptatretus stoutii) first react to light with a wave-like movement of their tail or head. They have also been observed curling up in response to light in captivity. After some time spent in light, Pacific hagfish tend begin to swim around and settle once reintroduced to the dark. This behavior led us to hypothesize that they are photosensitive. Therefore, we predicted that hagfish would spend more time under a darker section of the tank than a light section. An LED light fixed to the top of the tank illuminated the tanks during the trials and a digital video camera allowed us to monitor Pacific hagfish movement across the 30-minute trials. Pacific hagfish were allowed a 15-minute adjustment period in the dark after the tank apparatus was set up, before being exposed to light from the LED mounted in the tank. Our preliminary results suggest hagfish are, indeed, photosensitive. In response to bright light, hagfish began to move their tail and head then swam around the tank and either moved or stayed on the dark side of the tank. Additionally, a secondary experiment was set-up in which an LED light was turned on in the tank, while recording, in order to capture the reaction of the Pacific hagfish immediately after introducing the stimulus. Using video analysis, movements of the hagfish could be quantified both before and after the light stimulus was introduced in the tank. Our results raise interesting questions about the role of photosensitivity in deep sea animals and the diversity of photosensitivity within the hagfish lineage.