Japanese Sea Nettle (Chrysaora pacifica) — identification, habitat & look-alikes

The Japanese sea nettle is a stinging jellyfish of East Asian coastal waters in the northwest Pacific. Its gold-to-red bell is marked with a dark sunburst of stripes, and long, frilly hang below it like curtains. It doesn't live in US waters, so most Americans see it in public aquariums.

Appearance

Appearance: The bell is usually about 4–8 in (10–20 cm) across, and the largest reach about 12 in (30 cm). Four ruffled oral arms trail 2–3 times the bell's width, and eight clusters of thin tentacles around the rim, about 40 in all, can stretch to about 10 ft (3 m).

Look-alikes

Northern sea nettleChrysaora melanaster

The northern sea nettle is much larger and lives in cold northern waters such as the Bering Sea. The Japanese sea nettle is smaller, has more tentacles, and a different bell pattern.

Why they get mixed upBoth have striped bells and long oral arms, and aquariums often mixed up their labels.

Pacific sea nettleChrysaora fuscescens

The Pacific sea nettle is the one living along the West Coast, from British Columbia to Baja California. It has a golden-brown bell with a reddish tint and 24 maroon tentacles. The Japanese sea nettle has a bold, dark sunburst of stripes and about 40 tentacles.

Why they get mixed upBoth are gold-to-red sea nettles with long oral arms, and both are shown in US aquariums.

Where it lives

Typical habitats: Coastal seas
Bays
Range: Native to the northwest Pacific, including Japan, Korea, Taiwan, and China.
Preferred conditions: Prefers warm water. Young jellies grow best at about 68–75°F (20–24°C), and the species is reported from water of roughly 54–77°F (12–25°C).

Behavior

Diet: A predator that stuns prey with stinging cells. It especially likes comb jellies, and also eats small fish, fish larvae, anchovy eggs, copepods, and other zooplankton.

Life cycle

Reproduction: Each jelly is male or female. Females hold fertilized eggs on their oral arms until free-swimming larvae are released. The larvae settle on shaded, rough surfaces and grow into tiny , which can bud off clones or, when conditions are right, release baby jellyfish.

Cautions

Cautions: Its sting can cause a painful rash and burn-like marks. Serious reactions are rare, but a life-threatening case in a young child has been reported in the medical literature.

Name and classification

About the name: For a long time it was confused with the larger, more northern Chrysaora melanaster, and aquarium animals were often labeled with that name.