A species of clam that was only known from fossils dating back 28,000 years was discovered to be alive off the coast of California.
The small, translucent bivalve mollusk was found living intertidally near the Santa Barbara coast, ScienceAlert reported. It was determined to be Cymatioa cooki, and it had been discovered as a fossil in 1937 by a local woman named Edna Cook. The fossils come from a well-studied archaeological site dated to between 28,000 and 36,000 years old.
“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,” said Jeff Goddard, research associate at UC Santa Barbara’s Marine Science Institute and the co-author of the study detailing the discovery.
Goddard was searching for invertebrates to study in November of 2018 when he found a speck of about ten millimeters in length that caught his eye. The strange “wave” of the shell was something he had never seen before. He sent photos to Paul Valentich-Scott, a curator of mollusks at the Santa Barbara Museum of Natural History. Valentich-Scott scoured the scientific literature, which dates back to 1758, and later concluded that the clam matched the fossilized species recorded by Cook in 1937.
Given that the area is so well-studied, it is baffling that the micro-mollusk evaded discovery for so long. Goddard described the region as having a “long history of shell-collecting and malacology,” and that there are even “folks interested in the harder to find micro-mollusks.” This made it “hard to believe” for him that it took so long to discover the clam.
The reason behind the seemingly mysterious appearance, Goddard suspects, could be the marine heatwaves from 2014 to 2016. The heatwaves created unique currents that likely carried the mollusks to the region while they were planktonic larvae. If true, then it could mean that the clams may take up to two years to develop.
Discovering sea creatures thought to have been long extinct has happened before. An ancient, deep-sea mollusk, known as Monoplacophoran, was considered to be extinct for millions of years until they were discovered in 1952. Another notable discovery was the Coelacanth, a fish with an average weight of 200 pounds and a length 6.5 feet, which is believed to be a 65 million-year-old species. But perhaps the freakiest discovery is the Goblin Shark, a deep sea shark believed to have been around for 125 million years with a face to earn the name.
A big difference between those discoveries and the discovery of Cymatioa cooki, is that these sea creatures tend to live in hard-to-reach places, like the ocean floor, whereas Cymatioa cooki was discovered off the well-studied coast of Santa Barbara, California.