PHOTOGRAPHY OF OCEAN FLOOR — LAUGHTON 325 



of the tracks are made by animals on the surface and some by animals 

 beneath it. Plate 2, figure 2, shows the broadest tracks found (about 

 4 inches across) and is representative of many such tracks found 

 beneath the Atlantic. A similar track, but with much more pro- 

 nounced transverse marks was photographed by Zenkevitch from the 

 Russian research ship Vityas, in the Pacific. Although the central 

 part of the track is raised, it must have been formed by an animal on 

 the surface because of the regularity of marking. A possible interpre- 

 tation is that the track was made by a mud-feeding animal which 

 scoops the mud into its mouth with some form of arms or tentacles, 

 producing transverse marks and a ridge of ooze, the central depression 

 being made by a trailing tail. Possible animals to fit this theory are 

 decapod crustaceans and holothurians of the type shown in plate 6, 

 figure 2. 



Other interesting tracks are the sinuous and the spiral forms. These 

 appear to have been made by worms burrowing just below the surface 

 and stop suddenly when the worm burrows downward. The shapes of 

 these tracks provide interesting evidence of the way in which an 

 animal can search an area most economically and systematically. 



Many other interesting problems arise out of these photographs 

 concerning the relationship between fauna and their environment. 

 Photography will doubtless be used more and more in the future to 

 study deep-sea marine ecology. 



FUTURE USE OF UNDERWATER PHOTOGRAPHY 



It is clear from the above discussion that deep-sea photography has 

 its place in any investigation that includes the sea bottom. A photo- 

 graph is second best to direct observation, but until bathyscaphes be- 

 come more common, direct observation is not possible. It may be 

 advantageous, in sampling the bottom, to attach a camera to the corer 

 or dredge to estimate the sampling technique more efficiently. Cer- 

 tainly, if it becomes a practicable proposition to drill into the solid 

 rock of the seabed, photographic control would be most desirable. 



The deep-sea camera has been used as a tool in a number of ways 

 other than those described. Fish, squid, and the deep scattering layer 

 have been photographed in midwater using suitable triggering devices, 

 and the camera has been incorporated as the recording method for 

 the measurement of currents on the sea floor. Doubtless many other 

 uses will be found in the future. 



ACKNOWLEDGMENTS 



I am grateful to the director of the Lamont Geological Observatory, 

 New York, for permission to publish the photographs shown in plate 



