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Vol 57 No. 1 | Jan. 2005
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Biology Prof Discovers Some Marine Worms Build Houses

A chance encounter with Pectinaria californiensis, a marine worm found in West Coast ocean sediments, has led to the discovery of an unusual feeding method by its larvae.

Bruno Pernet, assistant professor of biological sciences at CSULB, specializes in marine invertebrates. While on a research leave at the University of Washington's Friday Harbor Laboratories before starting at CSULB this fall, Pernet accompanied another researcher who was dredging for sea urchins.

“We unexpectedly came up with lots of these worms that I was interested in studying, so I brought them back to the marine lab where I was working and spawned them and reared their larvae and was surprised to find these results,” Pernet said.

Those results, published in the Dec. 3 issue of the journal Science, showed that P. californiensis' tiny larvae construct mucus “houses,” essentially bubble-like structures that nearly surround the larva and are used as filters to collect food particles. Minute hairs. called "cilia," pump seawater containing the particles toward the larva's mouth.

“We don't know of any other larva that does anything like this, so it broadens the field of things we have to explain and understand in evolutionary terms,” Pernet explained. “How they actually capture particles affects how long they have to spend up in the water and that affects survival. I'm interested in how different feeding mechanisms affect what larvae can eat and how fast they can eat it.”

Worms play an important role in the food chain. Pernet speculated that the “houses” might also help larvae detect predators who touch the structures or serve as a deterrent, owing to their slimy quality. How well larvae survive in the water affects how many return to the seafloor as adults. “There are marine worms everywhere in the oceans, especially in soft sediment habitats like mud and sand, and they're ecologically important in many ways, including as fish food.”

One of Pernet's goals is to create a database chronicling the reproduction of marine invertebrates from central California to Baja California.   “This sort of compilation—of such things as reproductive seasonality, egg sizes, developmental patterns, and larval biology—is extremely useful for biologists interested in comparative aspects of development, life histories, population ecology, biogeography, and conservation,” he explained.

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