The Pacific Sea Nettle (C. fuscescens) is a large jellyfish with a bell of up to about 30 cm. in diameter. It has four long, spiraling tentacles surrounding its mouth that are known as “oral arms”. Around the perimeter of the bell are 24 marginal tentacles, organized in eight groups of three, which may trail several meters behind the bell. The exumbrella (upper, convex surface of the bell) is amber-colored and darkest near the margin (Carlton 2007).