Thread Sludgeworm    Notomastus tenius

As you start to dig a hole in the mid to low intertidal zone of a muddy or sandy mud beach you will notice threads spanning the cracks in the sediment.  These threads are polychaete worms that riddle the mud with their burrows.  They are around 1/16 inch wide and up to 8 inches long.

They are members of the family Capitellidae which are commonly found in sediments with a high organic component.  They are often quite abundant and are important for processing the organic material in the sediment.  In turn they are fed upon by a variety if predators including shorebirds.

They can be found from the intertidal zone to several hundred feet subtidally and from southern Alaska to southern California.