LOST SPECIES OF THE BAY AREA
Presumed Extinct: sooty crayfish, San Francisco horseshoe shrimp
As with the presumed extinct ivory-billed woodpecker reported in Arkansas in 2004, there is always the chance that a long-lost plant or animal will be rediscovered, thanks to persistent searching and luck. That’s true even in a busy metropolitan area like the San Francisco Bay Area. In May 2005, botanist Michael Park stumbled upon a population of Mount Diablo buckwheat (Eriogonum truncatum) on the slopes of Mount Diablo. The buckwheat was a species long thought extinct, last seen in 1936 by UC Berkeley botany graduate student (and later Save Mount Diablo cofounder) Mary Bowerman.
Spurred by the rediscovery of the buckwheat, it bears asking today which plants and animals endemic to – but presumed extinct in – the San Francisco Bay Area scientists continue to search for in the hope they may still be hanging on by a thread, waiting to be found and protected.
sooty crayfish (Pacifastacus nigrescens)
San Francisco horseshoe shrimp (Lightiella serendipita)
On one weekend every June, deep in the heart of the Sacramento-San Joaquin Delta, the town of Isleton comes alive to celebrate its annual Crawdad Festival. Curiously enough, amid the crawdad sausages and jambalayas, the only thing missing is the native crawdad that once inhabited local streams: the sooty crayfish (Pacifastacus nigrescens). Only two other crayfish are native to California’s waters: the Shasta crayfish (P. fortis), a state and federally endangered species found only in Shasta County, and the Klamath signal crayfish (P. leniusculus klamathensis) of far Northern California. From the original 1857 description by marine biologist William Stimpson, we know only that the sooty crayfish was four inches long, blackish, and “common in the vicinity of San Francisco.” It otherwise closely resembled the Shasta crayfish. In the late 1800s the species was reportedly common in Central California streams, including Alameda and Coyote creeks, turning up on occasion in San Francisco markets.
Since the sooty crayfish has vanished without a trace, we can only guess that invasive crayfish introduced for bait and food out-competed their sooty cousins. But that hasn’t stopped ecologist Robert Leidy from looking along the upper reaches of Coyote and Alameda creeks, much of which is pristine land with a native wildlife assemblage. “People rediscover species with periodic regularity in places that are fairly well studied,” says Leidy, “As a field biologist, there’s always that sexy idea of finding something long thought extinct.”
The Bay’s miniature San Francisco horseshoe shrimp (Lightiella serendipita)—one of just five Lightiella species known worldwide—is a cephalocarid, among the most primitive of crustaceans, harkening back 500 million years to the Cambrian period. In 1961, Meredith L. Jones, from New York’s American Museum of Natural History, dredged four of these tiny, eyeless shrimp from the muddy sand bottom of the Bay off Point Richmond, making it the only known benthic (bottom dwelling), non-fish species endemic to the Bay. Five more were found in 1987 and 1988 off Brooks Island and Coyote Point, but none have been seen since, despite a California Academy of Sciences “bio-blitz” in search of bottom-dwelling Bay creatures in 2000. Academy curator Rich Mooi says mud samples were taken throughout the Bay where Lightiella had been reported. “I would have expected that if they were there, we would have seen them,” says Mooi. But, he adds, “[the shrimp] are tiny, they’re hard to see, and people hate going through mud.” Then Mooi hints that Lightiella just might be lurking, overlooked, in one of the academy’s many jars of Bay mud, awaiting another sifting. Any takers?
Field Guide to the Lost Species of the Bay Area
SPECIES: sooty crayfish (Pacifastacus nigrescens)
LISTING STATUS: none
FIRST/LAST RECORDED: 1857/late 1800s
RANGE: reported specifically in Alameda Creek, Coyote Creek, Steamboat Slough, and other Bay tributary streams
HABITAT: freshwater Bay tributary streams
FIELD NOTES: the sooty crayfish hasn’t been seen in over 100 years; the sooty crayfish closely resembles its cousin the Shasta crayfish (Pacifastacus fortis) but is blackish, smaller in size (4 inches long), and has more slender, hairless hands (claws)
Crayfishes (Astacidae) of North and Middle America, by Horton H. Hobbs
Ask the Naturalist—All the Crawdads You Can Eat (Bay Nature), March 13, 1996, by Michael Ellis
SPECIES: San Francisco horseshoe shrimp (Lightiella serendipita)
LISTING STATUS: none
FIRST/LAST RECORDED: 1961/1988
RANGE: known only from San Francisco Bay at Point Richmond, Brooks Island, Coyote Point
HABITAT: muddy sand bottom
FIELD NOTES: although extensive sampling has been done to rediscover this shrimp at its type locality and other collection locations, “searching” for this species amounts to sorting through Bay mud; mud-raker Richard Mooi of the California Academy of Sciences has generously offered would-be shrimp seekers the opportunity to pick through jars of mud—with the proper training, of course—to make sure no horseshoe shrimp have been overlooked— Reach Mooi at (415)321-8270.
Animals of San Francisco Bay: A Field Guide to Its Common Benthic Species, by Rich Mooi, Victor G. Smith, Margaret Gould Burke, Terrence M. Gosliner, Christina N. Piotrowski, and Rebecca K. Ritger
The account excerpted above was originally featured in the October/December 2007 issue of Bay Nature magazine.
Illustrations by Devin Cecil-Wishing.