|Foods & feeding|
Research study 1
Spionids inhabit tubes in sediments where they feed on organic matter in the surface layers. An alternate feeding mode is facultative suspension-feeding. This type of feeding involves extending the 2 large anterior tentacles, arrayed in a novel helical pattern, into the water flow. The helical shape increases the surface area of the tentacles normal to the flow. Studies at Friday Harbor Laboratories, Washington show that thespionid Polydora kempi japonica will switch from a deposit-feeding mode to a suspension-feeding mode in response to concentration of suspended particulate matter in the water. By using their tentacles in this manner the worms can capture particles as large as newly hatched brine shrimp, as well as smaller flocculent material. By narcotising worms with MgCl2 and implanting them in the sediment along with normal control worms, the authors show that the helical form of the tentacles is controlled by the worms and is not a passive response to water flow.
NOTE the Family Spionidae includes about 40 west-coast species, of which about half are in the genus Polydora
The original photograph in the authors' has poor contrast (see photo on Left), but a better one for the related Pseudopolydora paucibranchiata is shown on the Right 4X
This photo clearly shows the
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