The hunters: Solem and Nelson (photograph by Davis) 



I had remained aloof from the collect- 

 ing in order to take notes, but now I 

 stopped writing for a moment to watch 

 the jellyfish in the shallow tray. As the 

 sun cast the organism's shadow on the 

 bottom of the pan, I saw its contracting 

 inner structure and waving tentacles 

 projected in shadow lines larger than 

 life. Somewhat to my surprise, I was 

 suddenly determined to catch one of the 

 creatures myself. Grasping a thermos 

 cup, I made some awkward passes at 

 the water, but kept missing the exasper- 

 ating animals. At last I triumphantly 

 maneuvered one into the cup and drew 

 it in. Then Solem, who had been col- 

 lecting steadily for the last ten minutes, 

 generously handed me his net. With 

 this more efficient instrument, I snared 

 two or three specimens at a fair distance 

 from the boat and transferred them to 

 the thermos with immense satisfaction. 



We then turned to the problem of 

 photographing the specimens. In the 

 water, the organism's structure had ap- 

 peared tenuous. Seen in silhouette, 

 against the pan, however, the exquis- 

 itely proportioned design was perfectly 

 etched, and we hoped to capture it on 

 film. As Davis and Solem worked, I 

 asked about the organs within the crea- 

 ture's umbrella. "Gonads," explained 

 Nelson. "With one recorded exception, 



wherever these fish have been taken, all 

 the specimens have been of one sex or 

 the other. The theory is that they don't 

 spread in the jellyfish, or medusa, stage 

 but in the polyp stage, attached to ducks 

 or other water fowl, or occasionally an 

 aquatic plant. The polyps themselves 

 exhibit no sexual structures or activities, 

 but when a polyp buds, the medusae it 

 produces are either all male or all fe- 

 male. The conclusion, therefore, is that 

 each colony of jellyfish probably starts 

 from a single polyp." 



"The possibility that intrigues me," 

 Nelson went on, "is that these jellyfish 

 are really quite common in lakes and 

 ponds but are never noticed or reported. 

 When a large population like this is 

 found, the implication is that it has been 

 gradually building up over several years 

 to the point where it is finally noticed. 

 In general, the distribution of the species 

 seems to be spotty, which is probably 

 attributable to their chancy means of 

 transportation." 



"I shouldn't think they would do well 

 in a stream that had much current," 

 Davis suggested. 



Nelson agreed. "So far, they have 

 nearly always been found in impounded 

 waters, which suggests that the body of 

 water has to be of a certain size, so that 

 it doesn't undergo extreme changes in 



temperature. A shallow pond or a run- 

 ning stream, for example, might not pro- 

 vide these conditions." 



Earlier, Davis had suspended our ther- 

 mometer a few inches below the surface 

 of the water. Now he pulled it up and 

 reported that the water temperature 

 was 77° F. 



In about an hour, we had collected 

 several dozen specimens — an adequate 

 series. A score of these would be pre- 

 served in formalin and added to the 

 Museum's research collection of inverte- 

 brates, where they would be available 

 for study by scientists here or in other 

 parts of the world. The remainder of 

 the specimens would be transported to 

 the Museum for photographing and ob- 

 servation as long as they survived. As 

 we surveyed our collection, now gath- 

 ered in a feathery mass at the bottom of 

 the thermos jar, Barbara Solem asked 

 if these tiny medusa forms were related 

 to the giant and dangerous Portuguese 

 "man-of-war." "Yes," was the reply, 

 "but distantly." Solem reminded us 

 that members of different classes of ver- 

 tebrates are more closely related to each 

 other than are members of the same 

 classes of invertebrates. Then he, too, 

 had a question. "If a group of whales is 

 a gam, what would you call a mass of 

 jellyfish?" At this, Dwight decided that 

 it was time to up anchor. With it, there 

 came an adequate sample of the life of 

 the quarry environment — water weeds, 

 algae, water insects, and minnows. Row- 

 ing back to the dock, we laid plans to 

 check the quarry again next year. 



We had packed our gear into the car 

 and were ready to leave the club grounds, 

 when we missed the dipping net. It had 

 been left in one of the boats. Hurrying 

 back to the quarry's edge, we discovered 

 that a party of young girls had taken 

 that boat out onto the water again. 

 There was nothing for it but to row 

 after them. A brief chase, and we were 

 within hailing distance. "Have you 

 seen a net in your boat?" we called. 

 "Oh, yes," they replied. "We noticed 

 it here. But we didn't touch it," they 

 assured us. As I reached over the side 

 and retrieved the net they held out, I 

 reflected that I, too — -yesterday — might 

 have found a net in a boat and never 

 once thought to dip it into the water. 



Page 5 



