Sea Walnut Comb Jelly

About

The sea walnut comb jelly (Mnemiopsis leidyi) is one of those animals that makes you stop and stare. Rows of iridescent comb plates catch the light and scatter it into rainbow pulses as this transparent little creature pulses through the water column. Native to the Atlantic coast of the Americas, it has become notorious as one of the more damaging aquatic invasive species ever recorded, having hitched rides in ballast water to the Black Sea where it collapsed commercial fisheries in the 1980s and 90s by devouring fish eggs and larvae at a staggering rate. That predatory appetite is worth keeping in mind for anyone interested in keeping one: this animal cannot be housed with fish or most other invertebrates, full stop. It requires a kreisel tank. A specialized circular or cylindrical vessel with a gentle, even water flow that keeps soft-bodied jellies suspended without dashing them against walls or intakes. The care involved is genuinely advanced, and sourcing appropriate live prey consistently is a real commitment. For keepers willing to meet those demands, though, watching comb plates ripple light across a darkened room is a genuinely rewarding experience unlike almost anything else in the saltwater hobby.