Pacific Sea Nettle (Chrysaora fuscescens)

The Pacific sea nettle (Chrysaora fuscescens) is a striking, large jellyfish common along the North American Pacific coast. Its bell can reach over three feet in diameter, trailing 24 long, ribbon-like oral arms and hundreds of thread-like tentacles. Its most distinctive feature is its rich, reddish-brown to golden-yellow coloration, often contrasted with darker radiating stripes. These trailing appendages are equipped with stinging cells used to stun prey, such as zooplankton and small fish. While its sting subdues plankton and small fish, it is typically only a mild irritant to humans. A graceful and powerful swimmer, it plays a crucial role in pelagic ecosystems, often providing food and shelter for other species, such as juvenile Pacific butterfish or cancer grabs in the open ocean.

Notes: Pacific sea nettles are less dependent on fish and other jellies as their feed compared to other Chrysaora species. In fact, they can grow over 30cm solely by feeding on freshly hatched brine shrimp. This dietary flexibility makes them one of the easiest jellyfish to cultivate, provided they have cool water and ample space. Their polyps and ephyrae are easily maintained at 16°C on a diet of freshly hatched brine shrimp. Strobilation can be initiated by lowering the temperature to 12-13 °C. While a single polyp can rapidly produce many ephyrae, these young often exhibit low activity, particularly when the parent polyp is aged.