humidity during a 1952 eclipse in Iraq. Petipa 

 (1955) sampled zooplankton during the 1954 

 eclipse in the Black Sea, U.S.S.R., and reported 

 that most of these organisms i-esponded by 

 rising towards the surface at totality. K. F. 

 Wiborg (personal communication, Bergen, 

 Norway) made studies off the Norwegian coast 

 during the 1954 eclipse, but poor weather — 

 overcast with strong winds — hampered the 

 collection of zooplankton and interpretation of 

 results. Some of the observations made during 

 the July 1963 eclipse have already been report- 

 ed. Skud (1964) recorded the responses of 

 herring, Clupea harengus, and the green crab. 

 Carcinus maenas; and Backus, Clark, and 

 Wing (1965) described changes in depth of 

 the scattering layers and the occurrence of bio- 

 luminescent flashes. 



Though the number of references dealing 

 with responses of marine organisms to solar 

 eclipses is small, there is a considerable back- 

 ground of information concerning reactions to 

 light — both in nature and in the laboratory. 

 The purposes of this article are to present the 

 more detailed observations made during the 

 eclipse of July 1963, to compare these observa- 

 tions with pertinent information from similar 

 .studies, and to add to the general knowledge of 

 phototactic responses and rhythmic behavior 

 patterns. 



OBSERVATIONS AND COLLECTING 

 METHODS 



The total eclipse of the sun occurred on Sat- 

 urday, July 20, 1963, and the path of totality 

 bisected the State of Maine (fig. 1). At Bar 

 Harbor, mideclip.se occurred at 21:45:00 

 Ephemeris time (17:44:25 ea.stern daylight 

 time), the sun's altitude was 25 degrees, the 

 path of totality was 53 miles wide, and the 

 duration was 59 .seconds (U.S. Naval Observa- 

 tory, 1961). All of the State experienced at 

 least 98 percent totality. At totality, cloud 

 cover varied considerably along the coast and 

 obstructed viewing in some areas, as did fog 

 patches in certain offshore areas. At Bar Har- 

 bor, the 20-m. Fish and Wildlife Service re- 

 search vessel Rorqual was used as an observa- 

 tion and collecting platform; though a light 

 fog reduced visibility on the water surface to 



PORTLAND 

 NEW YORK/ 



Maine 



SCALE IN MILES 

 10 20 30 



BOOTHBAY HARBOR 



Figure 1. — Path of totality and vicinity of sampling 

 areas during solar eclipse of July 20, \06:i. 



a few miles, the eclipse was fully visible. At 

 Boothbay Harbor, the 14-m. FWS vessel 

 Phalarope was used to collect samples. Holding 

 tanks were arranged at the Laboratory dock 

 to study responses of organisms held in cap- 

 tivity. Activity of the captive animals was 

 recorded every 15 minutes. All observations 

 are reported as eastern daylight time unless 

 otherwise specified. 



Observations and collections were made on 

 the day previous to the eclipse and on the day 

 of eclipse, beginning at 1600 hours and con- 

 tinuing at intervals through totality (1745) 

 until 2300. The 2-day .sequence was intended 

 to provide a test and control in detecting dif- 

 ferences in the behavior of animals, as was 

 the extension of observations through sunset 

 and early evening. Light measurements at 

 Boothbay Harbor were made at the surface 

 with a Gos.sen Lunasix electronic exposure 

 meter.' This meter lacked the flat interception 



' Trade names refiTred ki in this publicalion rln not im|j|y 

 endorsement of the products. 



260 



U.S. FISH AND WILDLIFE SERVICE 



