Fishes up to 1 foot in length were noted to make up the deep-sea fauna. It is sus- 

 pected, therefore, that relatively large organisms are available for them to feed upon. 

 Since there must be a rather complete food chain in the vicinity of the sea floor, it is 

 further assumed that living organisms represent a considerable quantity of the materials 

 observed suspended in the water. Conspicuous organisms were noted on most descents. 



On the sea floor, the planktonic animals could be better discerned because of the 

 bathyscaph's stationary condition. Here, fish, isopods, copepods, shrimp, medusae, and 

 other marine life could be viewed for longer periods. Frequently "clouds" of suspended 

 sediment, illuminated by the mercury vapor lamps, passed through the viewing area 

 (fig. 7). These were assumed to be generated by fishes outside the field of view. 



Animal response to light was found to be both positive and negative. Most of the 

 bottom fishes that live well below the penetration of sunlight showed little or no con- 

 cern for the strong artificial illumination. One fish, at 450 meters, which is still within 

 the influence of sunlight, displayed a strong negative reaction by darting into the sea 

 floor in complete panic. Cyclothone, the most abundant in numbers of any deep-sea 

 fish genus, were positively phototropic, but never appeared in concentrated numbers as 

 might be expected considering their frequent occurrence in net hauls. 



An undetermined species of isopod accumulated in the light zone, at times by the 

 hundreds. They appeared at nearly every location reached on the sea floor. As these 

 Isopods appear only as diffuse white areas in our photographs, it is highly probable 

 that they represent the type of animal noted in many photographs of the deep-sea 

 floor (fig. 8 and 9). Identification of animal forms such as were made possible here 

 represent a valuable contribution of the bathyscoph to our knowledge about small 

 deep-sea fauna. 



At the greater depths, the sea floor is quite firm. Materials apparently remain on the 

 surface of the sea floor for extended periods. At the 1000-meter level, south of Capri, 

 broken pieces of the eelgrass Posidonia were found on the sea floor (fig. 10). Although 

 these fragments represent a rich source of organic matter, no animals were seen to be 

 feeding on them. Dives to 170 and 2800 meters revealed the presence of wood frag- 

 ments, boxes, and bottles (fig. 11 and 12). 



sea floor 



A knowledge of the nature of the sea floor is useful in evaluating its probable effect 

 on sound reflection and absorption. Careful scrufiny of the sea floor was included in 

 the NEL program. The sea floor was the ultimate destination of nearly all the dives. 



On all descents in the vicinity of the Isle of Capri, the sea floor at 1000 meters was 

 found to be covered with a fine sediment. Two dives to 175 and to 300 meters, made 

 immediately adjacent to the island, revealed cobbles but no discernible bedrock. Sev- 

 eral attempts were made to locate rock outcrops at the base of the slope (900 meters) 

 leading up to the island (dives 27, 29, 33, 40, 41). The lack of a surface-ship fathometer 

 and other navigational aids precluded precise depth location and dives that exceeded 

 900 meters resulted. 



On dive 33, a narrow bench 5 to 10 meters wide was found at 450-meter depth south 

 of Marina Piccolo, Capri. Figure 13 is an artist's concepfion of the dive. At the seaward 

 edge of this bench, the sea floor abruptly dipped to form a slope of 50 to 60 degrees, 

 covered with a mantle of clay and silt. Although the bathyscoph was in a state of only 

 slight negative buoyancy, it would not rest motionless on the steep, soft, sediment cover 

 of the slope. Not wishing to halt the sliding descent of the craft, we skidded down the 

 incline. For ease of observafion and safety of the croft, it was fortunate that the bathy- 



12 



