. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 200 REPORTS FROM THE MBL GENERAL SCIENTIFIC MEETINGS Reference: «/«/. Hull. W3: 200-201. (October, 1997) Circadian Rhythms in the Lateral Eye of the Japanese Horseshoe Crab Takehiko Saito, Takasi Yamamoto1, Maureen K. Powers', and Robert B. Barlow (Marine Biological Laboratory, Woods Hole, Massachusetts 02543) The visual system of the "American" horseshoe crab, Limu- his pol\phemus, provides a clear example of the brain modulat- ing a sensory input. At night, efferent optic nerve fibers transmit neural signals to t
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 200 REPORTS FROM THE MBL GENERAL SCIENTIFIC MEETINGS Reference: «/«/. Hull. W3: 200-201. (October, 1997) Circadian Rhythms in the Lateral Eye of the Japanese Horseshoe Crab Takehiko Saito, Takasi Yamamoto1, Maureen K. Powers', and Robert B. Barlow (Marine Biological Laboratory, Woods Hole, Massachusetts 02543) The visual system of the "American" horseshoe crab, Limu- his pol\phemus, provides a clear example of the brain modulat- ing a sensory input. At night, efferent optic nerve fibers transmit neural signals to the lateral eyes from a circadian clock located in the brain (1). The efferent signals change the structure and function of the lateral eye (2), increasing its sensitivity to such a level that the animals can find mates underwater at night (). These circadian rhythms in retinal sensitivity persist in constant darkness and can be phase shifted by exposure to light pulses at various times during the circadian cycle (5). Although four extant species of horseshoe crabs inhabit various oceans of the world (6). circadian rhythms have been detected only in Limuliis ptil\phemus. which inhabits the eastern shores of North and Central America. Here we report that circadian rhythms occur in the visual system of the Japanese horseshoe crab, Tachypleus tridentatus, and differ in at least one property from those in Limulus. Three adult Tachypleus males were shipped to the Marine Biological Laboratory (Woods Hole, Massachusetts) from the Horseshoe Crab Museum (Kasaoka, Okayama, Japan). We were fortunate to receive these animals because they are protected by the Japanese government as a result of the recent precipitous decline in their population. Before experimentation, both Ta- chypleus and Limulus were entrained to natural environmental lighting for at least five weeks in aquaria at the Marine Biologi- cal Laboratory. Following techniques described elsewhere (5), we mounted a crab on a
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
