Development of a Low-Cost Thermal Gradient to Test Temperature Preference in Arachnids

Abstract

The purpose of my research is to develop a low-cost thermal gradient design using wood (white pine) for the walls and aluminum sheeting for the bottom. Heat will be provided by two heat lamps mounted underneath the tray. One lamp, using a 100-watt bulb, is underneath one end of the tray. A second lamp with a 40-watt bulb is underneath the middle of the tray, and the other end of the tray is resting on a container of ice. The inside of the tray was filled with 1 cm of sand. By using this design, I have created a thermal gradient ranging from 3 degrees Celsius to 60 degrees Celsius.

To test the reliability of my gradient design, I conducted temperature preference trials on Vaejovis cashi, a species of small scorpion from southeast Arizona. Twenty V. cashi were used in this study. To begin a trial, an individual scorpion was weighed and then placed in a tray approximately 60 cm from the end heated by the 100-watt bulb. Each trial lasted eight hours, with location/temperature checks conducted hourly. Hourly checks involved measuring distance from the 100-watt heat source to the scorpion and checking surface and scorpion temperature using a handheld infrared thermometer. Each scorpion was weighed at the end of their individual trial. At this time, trials are still ongoing so temperature preference has yet to be determined.