animal Type
Maximum Size

60 cm

(24 inches)



(12,000 feet)



Surface (epipelagic), twilight (mesopelagic), and midnight (bathypelagic) zones






This worm is always on the go.

While most worms crawl on the seafloor or slither through the mud, the gossamer worm (Tomopteris spp.) swims in the waters far above the ocean floor. Tomopteris lives in the midwater—an expanse of water deep below the surface and far above the bottom—and never touches the rocks and sand below.

Living in the water column, most Tomopteris have a transparent body to elude the gaze of predators lurking in the dim depths of the ocean’s twilight zone. Some gossamer worms also have a scarlet stomach that masks the light produced as the worm digests bioluminescent prey. When danger approaches, some species roll into a barrel shape to mimic an unappetizing jelly while others spew luminescent fluid out the tips of their swimming appendages called parapodia.

Tomopteris is also a fast and efficient swimmer. Researchers in MBARI’s Bioinspiration Lab and our collaborators at the Smithsonian National Museum of Natural History have been studying the mechanics of the gossamer worm’s swimming. They used high-tech tools—from lasers that illuminate the flow of water around the animal to high-speed video that captures rapid movements in detail—to understand how these worms swim so well. 

Like most worm-shaped animals that swim, Tomopteris moves by swishing their body side to side, but they also row their fleshy parapodia in sync with the body swishing. This effective technique provides speed and maneuverability for hunting prey and evading predators. Understanding how these worms swim could inspire new designs for underwater robots.

Scientists have described approximately 60 different species of gossamer worm. Most are just a few centimeters long, but the largest can reach 60 centimeters (24 inches) in length. Individual species can be challenging to distinguish. For more than 10 years, our team has worked with Smithsonian researchers to identify the Tomopteris worms that live in Monterey Bay. We have observed animals in the wild and collected specimens for close examination and genetic sequencing in the lab. We have learned that there are 18 different species of Tomopteris that live in our blue backyard—and several are actually species that are new to science.

The deep sea is the largest living space on Earth, but remains shrouded in mystery. This environment faces the same threats as other parts of the ocean, like overfishing, pollution, and climate change. Our work is helping us better understand the deep sea and its inhabitants. Our research findings will help us monitor how the amazing animals of the deep will navigate a changing ocean.


Video Clips


Byron, M.L., D.W. Murphy, K. Katija, A.P. Hoover, J. Daniels, K. Garayev, D. Takagi, E. Kanso, B.J. Gemmell, M. Ruszczyk, and A. Santhanakrishnan. 2021. Metachronal motion across scales: Current challenges and future directions. Integrative and Comparative Biology, 61(5): 1674–1688.

Francis, W.R., M.L. Powers, and S.H.D. Haddock. 2014. Characterization of an anthraquinone fluor from the bioluminescent, pelagic polychaete Tomopteris. Luminescence, 29: 1135–1140. PDF.

Haddock, S.H.D., L.M. Christianson, W.R. Francis, S. Martini, C.W. Dunn, P.R. Pugh, C.E. Mills, K.J. Osborn, B.A. Seibel, C.A. Choy, C.E. Schnitzler, G.I. Matsumoto, M. Messié, D.T. Schultz, J.R. Winnikoff, M.L. Powers, R. Gasca, W.E. Browne, S. Johnsen, K.L. Schlining, S. von Thun, B.E. Erwin, J.F. Ryan, and E.V. Thuesen. 2017. Insights into the biodiversity, behavior, and bioluminescence of deep-sea organisms using molecular and maritime technology. Oceanography, 30: 38–47. PDF.