Tube microstructure and formation in some feather duster worms (Polychaeta, Sabellidae)

Species of the sabellid polychaete genera Anamobaea, and Notaulax, are some of the most attractive sabellid polychaetes from coral reef areas due to their large colorful radiolar crowns. Tube microstructures of Anamobaea orstedi, Notaulax tenuitorques, and Notaulax sp. nov. are described. The studied sabellid tubes have three different types of microstructure. Most simple is irregular mesh microstructure which is composed of thin, long, and variously curved fibers of somewhat chaotic orientation (Notaulax tenuitorques). The irregular mesh microstructure could be plesiomorphic among sabellid tube structures. Oriented fibers in homogeneous matrix microstructure involves some kind of chemical control mechanisms that asserts the same orientation of all fibers (Notaulax sp. nov.). Anamobaea orstedi shows the most advanced pattern, a regular plywood structure, which is composed of thin subparallel or parallel to each other fibers that have different orientation in adjacent lamellae. Regular plywood structure has apparently greatest strength among organic tube structures of sabellids combined with good flexibility. Organic sabellid tube microstructures are likely species specific and have a taxonomic value.