A quarter-sized translucent jellyfish that appears mysteriously in ponds and lakes across North America. Native to China, it's conquered every continent except Antarctica. When they bloom, hundreds appear overnight — then vanish. We're tracking their seasonal emergence patterns and sequencing their genome to understand how they colonize new waters.
Last updated: March 2026. Only a mitochondrial genome exists for C. sowerbii. No complete nuclear genome has been sequenced despite its global distribution and ecological significance. This will be the first nuclear genome for this enigmatic freshwater cnidarian.
Downloaded and processed C. sowerbii occurrence records from GBIF. Over 1,000 sightings spanning 146 years, revealing seasonal bloom patterns and range expansion.
DataInteractive timeline map now shows the species' spread across North America from 1880 to present. Clear seasonal signal: 80% of sightings occur July-September.
TrackingC. sowerbii chosen as our flagship organism for its ecological importance, dramatic seasonal blooms, and complete lack of a nuclear genome sequence anywhere in the world.
MilestoneFound a swarm of tiny translucent jellyfish in your pond or lake? Report it immediately. These blooms are ephemeral — they appear suddenly and disappear within weeks. We need real-time reports to understand their seasonal timing and environmental triggers.
Join our field team during peak bloom season to collect live jellyfish for DNA extraction. Learn to identify C. sowerbii in the wild and contribute to the first-ever nuclear genome sequence for this species.
The jellyfish stage is just the tip of the iceberg. Most of the time, C. sowerbii lives as microscopic polyps attached to submerged surfaces. Learn to find and identify the cryptic polyp stage that most people never see.
Craspedacusta sowerbii is the world's only truly freshwater jellyfish. About the size of a quarter when mature, these translucent cnidarians appear in seasonal blooms that can number in the hundreds or thousands. They pulse through the water column feeding on zooplankton, their four radial canals and velum clearly visible under sunlight.
Native to China's Yangtze River basin, C. sowerbii has colonized every continent except Antarctica through human transport of aquatic plants and equipment. The species has a complex life cycle: most of the year it exists as microscopic polyps attached to submerged surfaces, reproducing asexually by budding. When environmental conditions align — typically in late summer when water temperatures peak — the polyps release medusae in massive synchronized blooms.
Despite its global distribution and ecological significance, the species remains poorly understood at the genomic level. Only a partial mitochondrial genome has been sequenced. A complete nuclear genome would unlock questions about freshwater adaptation, global invasion patterns, and the mysterious environmental triggers that control bloom timing. Michigan's clear lakes provide ideal conditions for both jellyfish photography and genetic sampling.