Pacific Sea Nettle (Chrysaora fuscescens)

Description: The bell of the Pacific sea nettle is a golden-brown color that has twenty-four long tentacles and four lacy oral arms attached to the bottom. The tentacles are more of a reddish-brown color while the oral arms are yellow. The diameter of the bell can be up to 30 centimeters (about 1 foot) wide, and the tentacles can reach lengths of over 4 meters (about 15 feet). In the wild, they typically live for 6-12 months, but in aquariums they can live for up to 18 months due to the lack of predators and the abundance of food.

Habitat: As their name suggests, Pacific sea nettles are found in the Pacific Ocean, usually along the coastlines of California and Oregon. They are less commonly found further north or south of these two states as well as across the Pacific Ocean along Japan’s coast. During colder seasons like fall and winter, these jellies stay near the surface of the water, but in the warmer spring and summer seasons they gather in swarms deeper down in the ocean.

Diet: Pacific sea nettles are carnivores that feed on other jellies and a variety of zooplankton, which also includes other jellies, larval marine creatures, the eggs of marine creatures, and pelagic snails. They catch their prey by spreading out their tentacles and oral arms in the water, and once they catch something they paralyze it with stinging cells called nematocysts. Their food is then digested in their gastrovascular cavity, which is like their stomach. If they catch larger prey, then food will be partially digested by the oral arms before entering the gastrovascular cavity. 

Tide Pool Tidbits:

• The genus name Chrysaora comes from the name of the Greek giant Chrysaor, son of Poseidon and Medusa. The name Chrysaor translates to “golden falchion” which refers to a weapon that could cut through armor, relating to this species’ powerful stinging ability. The species name fuscescens means dusky which refers to the color of the Pacific sea nettle’s bell. 

• Although they can’t see images, sea nettles have adapted to distinguish between light and dark by using little pigmented structures called ocelli, or “eye spots,” located on both the bell and tentacles. 

• Sea nettles keep themselves oriented in the ocean through something called statocysts, which help them know where the ocean floor and surface are. Statocysts are vesicles—sacs filled with fluid—containing mineral salts that activate their senses when they move.

Reference: Aquarium of the Pacific