Tsunami Travelers


The Tohoku tsunami of 2011 caused longest maritime migration ever recorded, with crustaceans, sea slugs and worms riding 4,800 miles from Japan to the North American west coast. (The Guardian)

What was the Tohoku tsunami?

Teachers, scroll down for a quick list of key resources in our Teachers Toolkit Text Set.

(A) An entire dock from the Port of Misawa, Aomori Prefecture, washed ashore near Newport, Oregon. Photograph by J. W. Chapman
(B) A fishing vessel washed ashore at Ilwaco, Washington, heavily covered with pelagic gooseneck barnacles, and carrying barnacles, isopods, amphipods, and mussels. Photograph by A. Pleus
(C) A Japanese barred knifejaw was discovered living in the stern well of a fishing vessel from Rikuzentakata, Iwate Prefecture, that washed ashore on Long Beach Peninsula, Washington. Photograph by A. Pleus
(D) Post-and-beam wood from Tōhoku coast, Honshu, washed ashore at Bandon, Oregon, and was heavily bored by the Japanese shipworm. Photograph by N. C. Treneman
(E) A buoy was found floating inside the Charleston Boat Basin in Coos Bay, Oregon, with a living Japanese limpet next to dead Japanese oyster. Photograph by L. K. Rasmuson
(F) A buoy washed ashore at Dunes City, Oregon, with living colonies of bryozoans. Photograph by A. Marohl
Photographs courtesy James T. Carlton et. al. “Tsunami-driven rafting: Transoceanic species dispersal and implications for marine biogeography.” Science 29 Sep 2017: Vol. 357, Issue 6358, pp. 1402-1406 DOI: 10.1126/science.aao1498

Discussion Ideas

  • The “tsunami travelers” described in the Guardian article are associated with a tsunami that hit the Japanese east coast in 2011. What was the Tohoku tsunami? Read through our short article for some help.
    • The tsunami was a series of powerful waves triggered by the strongest earthquake in Japan’s recorded history—a 9.0 magnitude temblor. The earthquake struck below the North Pacific Ocean, 130 kilometers (81 miles) east of Sendai. Sendai is the largest city in Tohoku, the northeastern region on the island of Honshu. The Tohoku tsunami hit the coast of Japan with waves up to 40 meters (132 feet) tall.



Map by G. Grullon, Science. From “Tsunami debris spells trouble,” Science 29 Sep 2017: Vol. 357, Issue 6358, pp. 1356 DOI: 10.1126/science.aao5677
  • How did all those tsunami travelers actually travel? These are species that cannot migrate long distances.
    • It wasn’t natural. The species rafted on pieces of debris generated by the tsunami. The Tohoku tsunami “generated five million tonnes of debris from the three prefectures of Iwate, Miyagi, and Fukushima. About 70% sank quickly to the ocean floor, according to experts, but countless buoys, docks, boats and other items with buoyancy were swept out to sea.”
      • Here’s a key takeaway from Science: “Rafting, or the transport of organisms across water on natural debris such as trees or kelp, is thought to have contributed to the colonization of islands and the exchange of life between continents. [Learn more about that process here.] More recently, rafting on human artifacts, such as large plastic items, has been growing in importance; these items survive longer at sea than their natural counterparts and can therefore carry their cargo further. The scale and spatial extent of the rafting event associated with the 2011 tsunami are, however, unprecedented.”




The Guardian: Tsunami carried a million sea creatures from Japan to US west coast

The Atlantic: Japanese Animals Are Still Washing Up in America After The 2011 Tsunami

Science: Tsunami debris spells trouble

Nat Geo: Tohoku Earthquake and Tsunami

Nat Geo: Landslides Help Explain How Life Reaches Remote Islands

(extra credit!) Science: Tsunami-driven rafting: Transoceanic species dispersal and implications for marine biogeography

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