Intertidal spiral burrows; Paraonis fulgens and Spiophanes wigleyi in the Minas Basin, Bay of Fundy

On some intertidal fine sands of the Minas Basin, Bay of Fundy, the tubicolous spionid polychate Spiophanes wigleyi coexists with the paraonid polychate, Paraonis fulgens. Paraonis feeds on diatoms buried on bedding planes within the sediment, and produces spiral traces 2-3 cm in diameter. Sediment preferences of both worms seem related to feeding behaviour: population densities of Spiophanes were positively correlated with mean grain size, and not with sorting, while population densities of Paraonis were not correlated with mean grain size, but were positively correlated with sorting. If found preserved in the fossil record, Spiophanes tubes would probably be identified as Skolithos , a trace fossil associated with the nearshore zone. Paraonis spirals bear a superficial resemblance to other spiral traces, such as Spiroraphe , found at abyssal depths.