Senses and Circulation
F.implexa have a single nuchal organ which is a ciliated sensory pit or groove located on the prostomium. It is a chemical receptor utilised for detection of food. For a sessile lifestyle F.implexa exhibits a particularly advanced brain relative to the complex brains seen in predatory polychaetae (Glasby, 2000). Furthermore, F.implex possess a pair of peristomial eyes (ocelli) used for determining light intensity and directionality (Glasby, 2000; Ruppert et. al., 2004).
Longitudinal Section: Filograna implexa specimen depicting internal structure
Photo by Emma Blacklock
F.implex hemal system conforms to the basic layout for annelids in general however differs in additional circulation of parapodia, gill structure and tentacular crown.
Anteriorly blood is moved through vessels dorsally transverse and cirum-oesophageal to a ventral vessel designed to deliver blood posteriorly. The tentacular crown is supplied with nutrient rich blood via a number of peripheral blind ended blood vessesl. During tentacle extension, contractile myoepithelial cells which surround vessel acts to consistently fill and empty tentacular crown. Blood leaving crown is shunted through the ventral vessel and moves posteriorly. This Famlily Serpulidae does not possess a traditional heart and therefore relies upon the contraction and relaxation fo myoepithelial cells also known as peristalsis to move blood throughout body.
In addition, studies have shown that within this family at least two blood pigments are present; Chlorocruorin and erthrocruorin (Glasby 2000). |