Sea squirts may lack thumbs, but they certainly can hitchhike. According to SERC’s Marine Invasions Lab, these marine invertebrates are heading north. In a new paper in BioInvasions Records, marine biologists discovered three new non-native species in San Francisco Bay (Microcosmus squamiger, Styela canopus and Molgula ficus), over 500 kilometers north of their previously recorded range. The lab suspects these sea squirts (a.k.a. ascidians or tunicates) hitched a ride on boats traveling up the California coast. A multiyear marine heat wave called “The Blob” might also have given them the necessary boost to settle into a new home. Going forward, the Marine Invasions Lab will watch closely to see how these species fare and what (if any) havoc they wreak.

Read more about these sea squirts at NEMESIS, the Smithsonian’s database for invasive species all over the U.S.
Microcosmus squamiger
Styela canopus
Molgula ficus

Written by Ryan Greene, science writing intern at the Smithsonian Environmental Research Center. Photos by Kristen Larson/SERC