According to Hunter\u2019s newest statistical analyses<\/a>, logs carrying rafting crinoids could float on even the most hostile oceans for a decade or more. Rafting crinoids and their driftwood vessels, Hunter says, \u201cwould have created a little island of activity\u201d in an otherwise nutrient-poor ocean.<\/p>\n Though the rugged mussels that accompanied the crinoids remain as relics of this early mode of marine transport, no other passengers were preserved. Hunter speculates that crinoid rafts could have ferried additional stowaways including plants, bryozoans, and crustaceans. Animals such as fish might have also trailed in their wake, feasting on the travelers.<\/p>\n Michael Simms, a paleontologist at National Museums NI in Northern Ireland who was not involved in Hunter\u2019s research, theorizes that these buoyed communities could have traveled thousands of kilometers, provided they could make it to the open ocean without getting caught in currents or sinking. They might have even traversed entire oceans, he speculates, although the exact routes they took can\u2019t be extrapolated from the fossil record.<\/p>\n Although this rafting lifestyle was once the subject of intense debate<\/a> among crinoid researchers, most now agree that at least two crinoid lineages spent tens of millions of years rafting. Scientists initially estimated that crinoids floated for a few years. More recently, Hunter, Simms, and others have extended these estimates to at least a decade, maybe two. Depending on factors like ocean currents, rafting longer could mean rafting farther for the crinoids and their passengers.<\/p>\n Simms based his calculations on<\/a> observations of modern driftwood to surmise how long ancient logs could have stayed afloat, even encrusted by crinoids. Hunter, meanwhile, is using statistical approaches to analyze crinoid fossils and reverse-engineer their time of death. These methods, he hopes, will add credence to the rafting hypothesis and derive more accurate estimates of floatation duration.<\/p>\n Rafting crinoids flourished until roughly 180 million years ago, when, some scientists think, the appearance of wood-boring organisms like shipworms drastically curtailed their drifting ways. Once their vessels collapsed, the crinoids would plummet to the bottom of the ocean, in many cases becoming frozen in time by the oxygen-starved seabed.<\/p>\n By analyzing fossilized crinoids, scientists are trying to determine how long and far they could have rafted. Some fossils even contain mussels, suggesting the crinoids supported a small ecosystem. Photo by Scott Camazine\/Alamy Stock Photo<\/p><\/div>\n Modern crinoids no longer raft attached to logs\u2014instead, some species get around by crawling along the seafloor or swimming with feathered arms. But that hasn\u2019t stopped the rafting process for other species. Now, creatures looking to hitch a ride enjoy a fleet of vessels even more durable than Jurassic driftwood: plastic.<\/p>\n \u201cEvery day we throw plastic in the ocean, so there is a continuous supply of tickets for these travelers,\u201d says Martin Thiel, a marine biologist at the Catholic University of the North in Chile.<\/p>\n In 2015, Thiel and his colleagues reported<\/a> that nearly 400 different types of organisms have been found rafting on floating litter, a figure that has only grown<\/a>. Compared to Jurassic logs, most plastics are highly resistant to decay. Forget decades, these plastic rafts could theoretically drift for centuries.<\/p>\n Figures like these raise concerns about the threat of invasive species, which now have a new way to surpass their natural distributions. According to Lars Gutow, an ecologist at the Alfred Wegener Institute in Germany, invaders riding on plastic rafts are a major threat to biodiversity that could lead to the homogenization of species on a global scale.<\/p>\n![\"crinoid](\"https:\/\/hakaimagazine.com\/wp-content\/uploads\/fossil-crinoid-rafting-1200x804.jpg\")
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