Sabella spallanzanii (Gmelin 1791), a polychaete annelid known alternatively as the giant European or Mediterranean fan worm, is an invasive marine pest species that was first detected in the Geelong arm of Port Phillip Bay in the late 1980s (Carey and Watson 1992).
This, no doubt, has implications for the sheer volume of water that this fan worm can filter in any given hour.
spallanzanii, and, overall, densities of this fan worm are too small to warrant major concern at present, though the situation is worthy of monitoring into the future.
Movement discrimination in fan worm radiolar eyes could be facilitated with little processing expense by an object gradually infringing on the field of view of increasing numbers of ocelli, until some threshold is crossed.
This further supports the notion that these fan worm photo-receptors function as a shadow or silhouette detector against the prevailing bright-illumination conditions of the shallow seas.
The unusual radiolar eyes of fan worms are compelling subjects for improving our understanding of eye evolution, the emergence of new sensory systems and behaviors, and signal processing in distributed visual systems.
To human thinking, the top of a tree seems a better place for lookouts, and another kind of fan worm does grow compound eyes there.
But Bok relishes the way the gill eyes in Christmas tree worms and other fan worms seem so improvised, such odd mixes of features cobbled together.
Bok is exploring fan worms' barely studied vision, possibly the only case of animals growing eyes on their gills.
A remarkable new genus and species of fan worm
(Polychaeta: Sabellidae: Sabellinae) associated with marine gastropods.
On piers you often see crabs, fan worms
and anemones on the pillars.
Interestingly, eyes in serpulids may be homologous to those in sabellids, a separate group of fan worms
, but do not appear to be homologous to the cephalic eyes of other annelids, which tend to detect light using r-opsins.