. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. D Figure 1. The orientation arena was an inverted fiberglass satellite dish ( m diameter) filled with water. The arena was surrounded by a Rubens cube coil 130 cm on a side. Prior to testing, each hatchling was placed into a nylon-Lycra harness that encircled the turtle's carapace without impeding swimming (15). The harness was connected by a short monofilament line to a lever arm mounted on a 360° rheostat. The rheostat was positioned on a post in the center of the orientation arena (2). The lever arm was free to rotate
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. D Figure 1. The orientation arena was an inverted fiberglass satellite dish ( m diameter) filled with water. The arena was surrounded by a Rubens cube coil 130 cm on a side. Prior to testing, each hatchling was placed into a nylon-Lycra harness that encircled the turtle's carapace without impeding swimming (15). The harness was connected by a short monofilament line to a lever arm mounted on a 360° rheostat. The rheostat was positioned on a post in the center of the orientation arena (2). The lever arm was free to rotate within the horizontal plane and could easily be pulled clockwise or counterclockwise by a swimming turtle. The arm thus tracked the direction toward which the hatchling swam. The central rheostat was wired to a computer in an adjacent room, which recorded the orientation of the turtle every 30 s with an accuracy of ±2°. Thus, the orientation of turtles swimming in darkness could be tracked. Methods: Detailed descriptions of methods are provided in ref #2. Each hatchling was tested once on either its first, second, or third night of captivity. Each trial began in the earth's field (coil off) with a dim light hanging in magnetic east so that hatchlings quickly established a course toward the light (2). The light was provided because hatchlings emerging from their nests at night under natural conditions find the sea using light cues associated with the ocean surface (25); light reflected from the ocean may also provide a directional cue necessary for hatchlings to initiate a seaward course (2, 26). After one hour, the light was turned off and the turtles were permitted to swim in darkness either in the unaltered magnetic field ( the coil remained off) or in a reversed field ( the coil was turned on 10-20 s after the light was turned off). Ten minutes after the light was turned off, the computer began recording the orientation of each hatchling at 30-s intervals. Thus
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
