some type of water chamber (McMahon and 

 Rigler 1963). For many studies, these methods 

 are undesirable because of the confinement of the 

 animal to a small volume of medium or because of 

 the solid boundaries nearby, both of which affect 

 the flow of water and possibly the movement of 

 limbs or other behavior by the animal (Lowndes 

 1935). Whenever the animal must be placed 

 within a relatively large volume of water, other 

 methods must be used. In a study of mate-seeking 

 behavior, Katona (1973) tethered female copepods 

 by means of fine stainless steel wires looped 

 about their bodies. While this method allows the 

 subsequent release of the animals unharmed, the 

 restraining wire can interfere with limb 

 movements. 



I have found a relatively simple method for re- 

 straining small crustaceans in large volumes of 

 water for extended periods of microscopic exami- 

 nation. A short segment (1-2 cm) of nylon mono- 

 filament fishing line of small diameter relative to 

 the organism is mounted in a dissecting needle 

 holder or pin vise. The free tip of the mono- 

 filament is then cut off square with a razor blade. 

 The animal is placed dorsal side up in a small 

 drop of water on a microscope slide or watch 

 glass. The tip of the monofilament is dipped in a 

 fresh droplet of "instant" drying polymer glue 

 (such as Dixon Duradix)^ and quickly applied and 

 held to the center line of the dorsal surface of the 

 animal for about 5 s. The organism can then be 

 lifted from the slide and placed in the test vessel, 

 with the dissecting needle holder mounted in a 

 micromanipulator or other type of clamping de- 

 vice. The rapid filming over of the glue and its 

 tendency to spread when placed on the wet ani- 

 mal sometimes makes a neat attachment difficult 

 and several attempts may be needed before a 

 satisfactory mount is achieved. 



Organisms restrained in this way appear to 

 carry out swimming movements in a natural 

 manner and live for several days on the mount. 

 Removal of the animal from the monofilament 

 usually results in its death. To make limb move- 

 ments easier to observe, organisms can be vitally 

 stained with neutral red prior to mounting (Dres- 

 sel et al. 1972). 



I have since found a description of this mounting 

 technique given by Scourfield (1900) in which he 

 regrets that no satisfactory cement could be found. 

 The polymer glues appear to solve the problem. 



^Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



Literature Cited 



Cannon, H. G. 



1928. On the feeding mechanism of the copepods, Calanus 

 finrrmrchicus and Diaptomus gracilis. Br. J. Exp. Biol. 

 6:131-144. 

 DRESSEL, D. M., D. R. HEINLE, AND M. C. GROTE. 



1972. Vital staining to sort dead and live copepods. Chesa- 

 peake Sci. 13:156-159. 



Gauld, D. T. 



1966. The swimming and feeding of planktonic cope- 

 pods. In H. Barnes (editor), Some contemporary studies 

 in marine science, p. 313-334. George Allen and Unwin, 

 Ltd., Lond. 



KATONA, S. K. 



1973. Evidence for sex pheromones in planktonic cope- 

 pods. Limnol. Oceanogr. 18:574-583. 



LOWNDES, A. G. 



1935. The swimming and feeding of certain calanoid cope- 

 pods. Proc. Zool. Soc. Lond. 1935:687-715. 

 MCMAHON, J. W., AND F. H. RiGLER. 



1963. Mechanisms regiilating the feeding rate of Daphnia 

 magna Straus. Can. J. Zool. 41:321-332. 

 SCOURFIELD. D. J. 



1900. The swimming peculiarities of Daphnia and its al- 

 lies, with an account of a new method of examining 

 living Entomostraca and similar organisms. J. Quekett 

 Microsc. Club 7:395-404. 



LOREN R. HAURY 



Woods Hole Oceanographic Institution 

 Woods Hole, MA 02543 



OBSERVATIONS ON 

 THE BIGEYE THRESHER SHARK, 



ALOPIAS SUPERCILIOSUS, IN 

 THE WESTERN NORTH ATLANTIC 



Thresher sharks of the genus Alopias are distrib- 

 uted throughout the tropical and warm temper- 

 ate zones of the world's oceans. Of the two species 

 reported from the western North Atlantic, the 

 thresher shark, A. vulpinus, is commonly found 

 in coastal waters of the middle Atlantic states 

 (Bigelow and Schroeder 1948). The second 

 member of the genus, the bigeye thresher, A. 

 superciliosus , is a little known offshore resident 

 of the continental slope and open sea. 



Lowe first described the bigeye thresher in 

 1840 from a specimen taken off the island of 

 Madeira (Bigelow and Schroeder 1948). The 

 species was not reported again until 1941 when 

 Springer (1943) documented the occurrence of a 

 gravid female taken near Salerno, Fla. Records of 

 other bigeye threshers from the Atlantic include 

 a gravid female, two embryos, a juvenile male, 

 and an 18-foot specimen all taken from the north 



221 



