Phacellophora

Phacellophora camtschatica Brandt, 1835 : Egg-yolk Jelly
Phylum Cnidaria / Class Scyphozoa / Order Semaeostomeae / Family Ulmaridae / Subfamily Sthenoniinae
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Among the more massive jellies to visit the waters of California and other West Coast locations is the egg yolk jelly. With a bell up to 60 cm diameter and dozens of thin, white tentacles extending for 10 to 20 feet, this jelly typically drifts motionless or with gentle pulsing. In this way it acts like a gelatinous drift net, capturing its preferred prey of other jellies that stumble into the mass of tentacles. As seen in the bottom photo, the tables can be turned when jellies come too close to shore. Here a rose anemone (Urticina lofotensis) has snared a large meal of gelatinous flesh.

Since Phacellophora specializes on capturing medusae, the tentacles and oral arms are sticky and have only a mild sting. Compared to the sea nettle and purple-striped jelly, the oral arms are relatively short and folded. The name “egg yolk” is derived from the central yellow mass of gonad tissue surrounded by a whitish to yellowish bell. The bell margin is marked by 16 clusters of tentacles, along with 16 lappets and 16 rhopalia.

Phacellophora is a delicate jelly that doesn’t hold its shape very well. Water motion produced by passing by too close results in a contorted, seemingly lifeless mass. Take a close look at the bell and you will likely find tiny hitchhiking crabs and amphipods, and occasionally juvenile fish that use the bell as a mobile home. Egg yolk jellies can be found in eastern Pacific temperate waters from the Gulf of Alaska to Chile. On occasion they can be relatively abundant in Monterey Bay, but do not form concentrated swarms. It is relatively easy to establish polyps and culture Phacellophora in captivity. When provided appropriate aquarium conditions (such as a kreisel tank), the medusae do well under captive conditions. They are occasionally displayed at public aquariums that feature jellies.

Phacellophora camtschatica, video courtesy of Patrick Anders Webster, Carmel Bay CA, September 2013

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