In April, thousands of jellyfish relatives known as Velella velella washed ashore on Oregon beaches, and now the same thing has happened in New Zealand, littering Fitzroy Beach in New Plymouth.

Commonly known as by-the-wind sailors, the blue, gelatinous velella skim across the surface of the ocean eating plankton, pushed along by the wind. Kelly Sutherland, assistant professor of biology in the Clark Honors College at the University of Oregon, told Newsweek that because they lack any other form of propulsion they travel at the whims of the wind.

“When winds change, they end up getting washed up on shore because of the sails on their back,” Sutherland said.

Velella are harmless to humans and common in the Pacific Ocean, but they may make your favorite beach stink if the wind forces them onto shore.   

Sutherland studies the intersection of marine biology and physics to gain an understanding of how organisms interact in their fluid environment. She received her doctorate in biological oceanography from Massachusetts Institute of Technology and Woods Hole Oceanographic Institution in 2010. Before teaching at the University of Oregon, Sutherland was a postdoctoral scholar in bioengineering at the California Institute of Technology.