Living Fossils Thrive on Ocean Floor

HONSHU, Japan一 A symbiotic relationship between two marine lifeforms thought to be extinct for 273 million years was found on the ocean floor. The two creatures had disappeared from the fossil record for hundreds of millions of years before scientists documented the species in a June 15 study. Off the coast of Honshu and Shikoku, Japan at depths exceeding 300 feet scientists found non-skeletal corals growing from the stalks of a species of crinoids known as the Japanese sea lily, a marine invertebrate found off the west coast of Japan generally on the continental shelf. The Japanese sea lily has wide feathery feeding arms attached to a U-shaped mouth. This symbiotic relationship is a parallel of one between coral and crinoid recorded in fossils from the Paleozoic era. “These specimens represent the first detailed records and examinations of a recent syn vivo association of a crinoid (host) and a hexacoral (epibiont),” said the team in the June 15 study. “And therefore analyses of these associations can shed new light on our understanding of these common Paleozoic associations.” Symbiotic relationships between crinoids and corals are documented throughout the Paleozoic era, a geological time that began with the Cambrian explosion and is associated with an extraordinary diversification of...