ELLIOTT ET AL.: THE CAVE FAUNA OF CALIFORNIA 
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Francisco; Illinois Natural History Survey, Urbana; University of Texas, Biodiversity Collections, 
Austin (about 1,000 California records are deposited in the Biospeleology collection); and the U.S. 
National Museum of Natural History, Washington, D.C. 
Overview of Fauna 
Sea Cave Fauna 
California’s sea caves sometimes have dark zones, and may contain many marine invertebrates 
and fishes that are attracted to dim light, darkness, or the shelter that crevices provide. California 
sea lions and harbor seals sometimes shelter in the caves (Fig. 12 in the contiguous photographic 
section). A troglobitic isopod has been found in two caves. 
Henderson (1983, 1988) described in detail the marine ecology of two caves on Santa Cruz 
Island. Diablo Anchorage Cave has two entrances and is subject to the prevailing, violent north¬ 
west swell, which enters the west entrance and exits the smaller east entrance, a blowhole. The cave 
is usually submerged and the bottom is floored with boulders, influencing the variety of inverte¬ 
brates. The high flow of seawater and nutrients support filter feeders such as white sponge (Fig. 
13), blue sponge, corals, barnacles, rock mussels, polychaete worms, and their predators, such as 
California spiny lobster. Resident fishes include rockfish, opaleye, perch, sheepshead, blacksmith, 
senioritas, spiny dog shark, and swell shark (scientific names are listed in Appendix 1). The two 
sharks are night or dim-light feeders especially attracted to this cave, forming tangled masses of 
many sharks. 
Fry’s Harbor Cave has one entrance in the lee of Santa Cruz Island, calmer water than Dia¬ 
blo Anchorage Cave, less nutrient input, and a silty bottom with breakdown false floors creating 
upper and lower galleries. This environment attracts a different community. There are few lobsters, 
but many black abalone feeding on algal bits and kelp drifting in from the entrance. Green 
anemones grade from green near the entrance to translucent white with pink highlights, owing to a 
loss of symbiotic green algae in their tissues in the darkness. Commonly seen are giant rock 
scallops and nudibranchs, including a new species discovered there, Jorrunna pardus, the leopard 
spot nudibranch. 
Two mainland sea caves, Brigadune Cave (Cliff House Cave) and Sutro Baths Cave (Sutro’s 
Cave), San Francisco County, contain an undescribed troglobitic terrestrial isopod, “Undetermined 
Oniscidea.” Cliff House Cave’s entrance is usually partly blocked with granitic beach sand and tree 
trunks. These are the only records of a troglobite from California sea caves. 
A few caves on the Farallon Islands contain the troglophilic rhaphidophorid cricket, Faral- 
lonophilus cavernicolus, a genus unique to those islands. The cricket colonies are moderately large 
(see Crickets overview below). The Farallon Islands were connected to the mainland during the 
low sea level stands in the late Pleistocene Epoch between about 25,000 and 15,000 ka and/or 
about 125,000 ka. Perhaps the crickets were distributed from the mainland to the present islands, 
and became isolated there relatively recently. The arboreal salamander, Aneides lugubris, is also 
known from sea caves on the Farallons and mainland caves (see Herpetofauna overview and 
Appendix 1). 
Another troglophile, Brackenridgia heroldi (Fig. 14), may have originated from littoral envi¬ 
ronments; the Oniscidea were ultimately derived from marine ancestors (Broly et al. 2013). This 
terrestrial isopod, though blind and depigmented, was originally known from the seashore at San 
Mateo, San Mateo County, and up to 1,200 m in Muir Woods, Marin County, where it occurs in 
leaf litter and other organic debris. It is known from 39 terrestrial caves in eight counties from the 
