Scientists in Southern California have recently found a living specimen of a minuscule clam that was previously only found in fossil form on the shores of Santa Barbara.
The fossils of the clam were previously identified by George Willet among almost a million mollusc specimens in 1937, when the ground was being dug up to lay a sewer pipeline in Baldwin Hills, Los AngelesBelonging to the Pleistocene epoch, the fossils were estimated to be between 36,000 and 28,000 years old.
The clam is called Cymatioa cooki and is translucent with cryptic habits, according to the researchers.
Discovering the clam specimen
In November 2018, Jeff Goddard, a research associate at UC Santa Barbara’s Marine Science Institute, found the tiny clam alive and well in the tidal pools of Naples Point, Santa Barbara, while engaged in a search for nudibranch sea slugs.
“Their shells were only 10 millimetres long. But when they extended and started waving about a bright white-striped foot longer than their shell, I realised I had never seen this species before,” he said in a press release.
The clam is called Cymatioa cooki and is translucent with cryptic habits, according to the researchers. | Photo Credit: Jeff Goddard/ ZooKeys
The find surprised Mr Goddard as he initially mistook the clam to be of a new, undiscovered species. As the rocky shores of Santa Barbara are teeming with various forms of marine life, the spot is a favourite among scientists and marine biology enthusiasts. In fact, Mr Goddard has studied the intertidal habitats of Santa Barbara for many years, including Naples Point, where the clam was found.
“It’s not all that common to find alive a species first known from the fossil record, especially in a region as well-studied as Southern California,” he said.
While he took pictures of the clam, Mr. Goddard did not collect the specimen, since it seemed rare. Unable to identify the species of clam, he sent its pictures to Paul Valentich-Scott, the curator emeritus of malacology at the Santa Barbara Museum of Natural History. After many unsuccessful trips, the pair finally spotted the clam again.
“This really started ‘the hunt’ for me,” Mr Valentich-Scott said. “When I suspect something is a new species, I need to track back through all of the scientific literature from 1758 to the present. It can be a daunting task, but with experience it can go pretty quickly,” he added.
The tiny Cymatioa cooki clam (bottom centre, marked with an arrow), sitting next to a chiton in the tidepools of Naples Point | Photo Credit: Jeff Goddard
They decided to refer to an illustration in a paper that described the species in 1937, which appeared to closely match the newly found specimen. Mr. Valentich-Scott also requested the Natural History Museum of Los Angeles County for Willett’s original specimen— the ‘type specimen’ that would serve to pin down the species.
Mr. Goddard also located another specimen- a single empty shell in the sand under a boulder at Naples Point. A comparison of Willett’s fossil and the Naples Point finds confirmed that this was indeed the same species— a living fossil of sorts.
The paper based on the find
Published in the journal ZooKeys, the paper outlined the details of the clam. According to the study, only three living specimens have been discovered to date. Cymatioa cooki is thought to have a commensal relationship with burrowing invertebrates, although their true habitat has still not been found.
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“The Pacific coast of Baja California has broad intertidal boulder fields that stretch literally for miles,” Mr Goddard said, “and I suspect that down there Cymatioa cooki is probably living in close association with animals burrowing beneath those boulders.”
The researchers suspect that the clams were transported as planktonic larvae from much farther south to Naples Point during the marine heatwave of 2014-2016, which drove numerous species in the northeastern Pacific Ocean northward.
This is a possible explanation as to why no one spotted this living fossil before 2018—including Mr Goddard, who has worked on heterobranch sea slugs in the area from 2002.
Named after Miss Edna T. Cook, the clam is not the only ancient organism that was found to be alive among the fossils documented by George Willett. At least three other species were also found near the coasts of California and Peru. Although it is only the Cymatioa cooki has eluded observers for over 80 years.
- Scientists in Southern California have recently found a living specimen of a minuscule clam. The clam is called Cymatioa cooki and is translucent with cryptic habits, according to the researchers.
- In November 2018, Jeff Goddard, a research associate at UC Santa Barbara’s Marine Science Institute, found the tiny clam alive and well in the tidal pools of Naples Point, Santa Barbara.
- The researchers suspect that the clams were transported as planktonic larvae from much farther south to Naples Point during the marine heatwave of 2014-2016, which drove numerous species in the northeastern Pacific Ocean northward.
