Between 2012 and 2017, debris from the 2011 tsunami in Japan carried 289 living marine species across the Pacific Ocean, stranding them along the coasts of Hawaii and the west coast of the United States. These species included mussels, worms, crustaceans, and other coastal organisms, many of which were not expected to survive such a long journey. The debris, which included plastic and fiberglass materials that do not degrade, provided a stable environment for these organisms to survive for six years or more. The tsunami, triggered by a magnitude 9.0 earthquake on March 11, 2011, reached heights of 38 meters on the Tōhoku coast of Japan, tearing millions of objects from the coastline and carrying them into the North Pacific. These objects, including buoys, crates, boats, and docks, formed a fleet that began to strand along the U.S. and Hawaiian coasts starting in 2012. The slow movement of the debris—traveling at a speed of 1 to 2 knots—allowed some organisms time to adjust to the new environment, despite the journey being considered biologically improbable. A team of researchers led by James Carlton from Williams College, along with Greg Ruiz from the Smithsonian Environmental Research Center and John Chapman, conducted a five-year inventory of the species found on the debris. Their findings were published in the journal Science on September 28, 2017, documenting the presence of 289 living species originally from Japan. Mussels were the most common, followed by worms, hydrozoans, crustaceans, and bryozoans. The researchers noted that this number is likely a lower bound, as many other species may have gone undetected. The debris stranded along a vast coastline, from Hawaii to Alaska and California. The use of non-degradable materials like plastic and fiberglass, which became widespread from the mid-20th century, allowed these objects to remain afloat for extended periods. Researchers expect the proportion of such materials in the ocean to continue increasing. The study noted that the term "invasive" might be misleading, as the inventory documents the crossing of species rather than their establishment on American coasts. The phenomenon, described as unprecedented in known history, has implications for marine biogeography. It shows that a tsunami or major storm, combined with non-degradable materials, can move an entire stretch of coastline. One example is the snail Crepidula onyx, which is native to the west coast of America but has become an invasive species in Japan. It has now returned to America, attached to Japanese debris.