Our interest in brittle stars began after the completion of our collection tanks. Most groups had a collection of brittle stars in their tanks. As we observed them we noticed they were always found under rocks. After further research we discovered they were highly sensitive to light and therefore always seeking shelter to avoid light. We then decided to use them in our experiment. In the field, we began to notice different patterns of movement among two species of brittle stars; Ophiocoma echinata and Ophioderma appressum, more commonly known as the Blunt Spined Brittle Star and the Banded Arm Brittle Star respectively. We used both species to determine if light would play a factor in the brittle stars rate of movement. The rate of speed of both species was calculated by measuring the amount of time it took to hide from the light and the distance they moved in that time. We first measured the rate without adding artificial light to use as a control. Then we began trials using a flashlight to compare the rates. After, to further our research, we used colored filters on the flashlight to change the intensity of light available to the brittle stars. Unlike the previous experiment, only Ophiocoma echinata was used to monitor the effects of light filtration. We hypothesized that the brittle stars will avoid light by moving faster towards a shadow or some place to hide. When there is a continuous and more intense source of light present, they will move faster to escape the light.
This was the set up used to calculate the brittle stars rate of movement.