162 



Life 



Fossil bathypelagic fishes have been found 

 abundantly in Late Miocene shales at Lom- 

 poc (north of Point Conception) and the 

 Santa Monica Mountains. According to 

 David (1943), 82 per cent of the specimens 

 from the Upper Mohnian (Late Miocene) 

 of Santa Monica Mountains are bathype- 

 lagic, including Cyclothone as the most 

 abundant genus, Lampanyctus, and several 

 other genera. The abundance of bathype- 

 lagic fishes at this part of the Miocene Epoch 

 accords well with the deepening water in- 

 ferred from the foraminiferal faunas (Pierce, 

 1956). 



Samples of basin floor sediment provide 

 some information on the kinds of pelagic 

 organisms living in the waters above, but of 

 course they do not in themselves show the 

 depth zone in which the pelagic forms live. 

 In the central Santa Barbara Basin, where 

 there are few benthonic forms, samples show 

 the presence of many shells of the pteropods 

 Clio and Cavolina and of the heteropod 

 Spiratella (Hartman and Barnard, 1958). 

 Many thin transparent shells of Cyclopecten 

 have been found in at least 25 samples from 

 the floors of San Pedro and Santa Monica 

 Basins, and a few living specimens have also 

 been recovered. Since the sediments of 

 these particular basins support very little to 

 no benthonic life, it seems probable that the 

 Cyclopecten does not live on or in the bot- 

 tom, but that it spends much of the time 

 just above the bottom. Like some other 

 pectens, this one doubtlessly has the ability 

 to swim or make long leaps by a jet action 

 produced by clapping its two shells together. 

 Thus, Cyclopecten is at least a semipelagic 

 animal. 



Photographs taken with the benthograph 

 between the sea surface and the bottom show 

 many trachyhne medusae, siphonophores, 

 and scyphozoans (Hartman and Emery, 

 1956). Four diff"erent kinds of trachyline 

 medusae (Fig. 140) have estimated diameters 

 as great as 15 cm with 23 to 32 tentacles ex- 

 tending outward another 15 cm. These are 

 closely related to others seen from the bathy- 

 scaphe F.N.R.S. III in the Mediterranean by 

 Peres, Picard, and Ruivo (1957). At least 

 four kinds of siphonophores were recog- 



nized, some so long as to pass beyond both 

 sides of the field of view of the camera; they 

 may easily be more than 3 meters long. 

 There were two kinds of scyphozoans, one 

 about 30 cm in diameter. Of 138 coelente- 

 rates, 112 were photographed within 90 

 meters of the bottom. All except 2 of 82 

 trachyline medusae were near the bottom of 

 the San Nicolas and Santa Catalina Basins 

 (3.7 and 4.0° C, respectively). In contrast, 

 nearly all the siphonophores were near the 

 bottom of the San Pedro Basin (5.1°C) or 

 near the side slopes of the San Pedro and 

 Santa CataUna Basins where the water is 

 even warmer (Fig. 141). Restriction of 

 forms to particular basins suggests the pres- 

 ence of environmental controls, perhaps 

 limited tolerances to temperatures, and their 

 restriction to bottom waters suggests that 

 they may feed on smaller mud-eating ani- 

 mals which live on or just above the sedi- 

 ments. All these bathypelagic coelenterates, 

 and especially the trachyline medusae and 

 siphonophores, are obviously so fragile that 

 they would be destroyed if caught in ordi- 

 nary nets, and so far as known no specimens 

 of them have been recovered in this region. 



Shelf Environment (Sublittoral) 



Plants of the subhttoral are dominated by 

 the giant kelps. Most abundant and largest 

 of these brown algae is Macrocystis pyrifera, 

 which with exceptional growth reaches a 

 length of 200 meters and a weight of 140 kg 

 (Frye, Rigg, and Crandall, 1915). It con- 

 sists of blades about 30 cm long attached 

 through a 5-cm teardrop-shaped float to a 

 stipe or stem. One or more stipes extend 

 down to a holdfast, or root-like structure 

 (Fig. 142), which anchors the kelp to the 

 bottom, ordinarily to bedrock, but some- 

 times to loose cobbles and even rarely to the 

 shell of a living abalone. According to 

 Warren Thompson (personal communica- 

 tion), massive holdfasts may also allow 

 growth of the kelp over sand bottom. To a 

 diver the kelp beds look like towering forest 

 trees reaching to the surface and then spread- 

 ing out as a thin flat canopy. The elkhorn 



