| Pleurobranchaea californica |
La Jolla Shores
Pleurobranchaea californica MacFarland, 1966
One of the largest opisthobranchs on the west coast of the U.S., let alone anywhere in the world, Pleurobranchaea californica is definitely the vacuum cleaner of this subclass. While west coast species like Aplysia californica and A. vacarria exceed its size and may consume more biomass than Pleurobranchaea (in the previous case biomass equals grams of algae or vegetable, rather than animal matter) this species dining habits make it quite unique. Unique also is its observation by divers, as it is a deepwater species, found primarily below depths of 30-1200 feet. Range is from Port Orford, Oregon to San Diego, California on the Pacific Coast.
Its mottled brown mantle closely resembles the mud, sand bottom on which the species forages. Like Berthella and Pleurobranchus, it is a member of the Order Notaspidea, or Side-gilled sea slugs. In Pleurobranchaea, the gill is large, often extending from beneath the notum. The foot is long, extending far behind the dorsum, unlike other members of the Order.
I have examined the gut contents of specimens up to nearly 10 inches in length, to learn that they feed not only on all variety of sand and mud bottom invertebrates, but unsuspecting fish, such as small sole and sanddabs. The most interesting aspect of its feeding behavior is that it cannibalizes its own species, a 10 inch individual examined contained 7 one inch younger brethren.
Seems like the term "ugly sucker" really begets this critter, that only a mother could love.
David W. Behrens
Pacific Coast Nudibranchs
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