How do you tag a jellyfish?  

They’re so soft—so squishy! Where to put a tag—and why bother? Questions like these moved scientists from the Monterey Bay Aquarium, the Monterey Bay Aquarium Research Institute (MBARI), Hopkins Marine Station and other institutions around the world to publish the first comprehensive how-to tagging paper for jellyfish researchers everywhere. This missing manual was long in the making

A wild sea nettle swims off Point Lobos near Carmel. Photo ©Bill Morgan

Tommy Knowles, a senior aquarist at Monterey Bay Aquarium, explains why.  Historically, ocean researchers demonized jellies as “blobs of goo that hurt you,” and that interfered with scientific gear. That changed in the  latter part of the 20th century as scientists grew keen to understand entire ecosystems, not just individual plants and animals. Knowing who eats what, how, where and when, they learned, is critical for conservation.

Jellyfish, however, remained a very under-appreciated member of the ecosystem for years, largely because so little was known about them.

Senior Aquarist Tommy Knowles and his colleagues work in the lab and in the filed to advance jellyfish science. Photo by Monterey Bay Aquarium/Tyson Rininger

“People didn’t know how to keep them alive in the lab or even on the boat,” says Knowles. Today, the field is coming into its own at a time when climate change has added urgency to the need to understand ecosystems in order to preserve ocean health.

A growing subject of interest

Understanding jellies is a concern for fisheries managers, too, since some jellyfish species prey upon the young and compete for food with the adults of commercially important fish. Other jellies impact tourism when blooms of stinging species foul beaches.

It’s not all negatives. We know that jellyfish play important roles in healthy marine ecosystems, by sheltering juvenile fish and crabs under their swimming bells, and nourishing hundreds of ocean predators. Jellies are a significant food source for ocean sunfish (the largest bony fish on the planet) and the endangered Pacific leatherback sea turtle, California’s state marine reptile.

A barrel jellyfish (Rhizostoma octopus) is tagged by a diver with an accelerometer using the “cable tie” method. Courtesy Sabrina Fossette/NOAA

As with other marine species that live and travel underwater—out of sight of human researchers—electronic data tags are useful tools for tracking jellies’ movements. Which gets back to the question: Just how do you tag a jellyfish? Continue reading How do you tag a jellyfish?