Studies on a New Zealand Serpulid Pomatoceros Coeruleus, Schmarda.

• Main Author: Knox, G. A.
• Format: Other/Unknown Material
• Language: English
• Published: University of Canterbury. Zoology 1949
• Subjects: New Zealand; Carbonic acid
• Online Access: http://hdl.handle.net/10092/5635; https://doi.org/10.26021/6410

(1.) It is shown that the animal studied belongs to the genus Pomatoceros. Its specific status is uncertain. (2.) The species is widely distributed throughout New Zealand and has also been reported from South Africa. (3.) The anatomy and some of the more interesting aspects of histology are described in detail, comparison being made with other Serpulids. (4.) The longitudinal muscles are well developed and the circular muscles much reduced, an adaption to the tubicolous habit. (5.) One pair only of nephridia is present in the thorax, opening internally by large ciliated coelomostomes into the peristomial coelom and externally by a common pore at the anterior dorsal end of the body. Excretory products are probably extracted from the blood in the form of guanine. (6.) The nervous system consists of a brain, formed from two pairs of united ganglia, situated in the prostomium and united to two sub-oesophageal ganglia in the peristamial segment by dorsal and ventral connectives on each side. The two ventral nerve cords are widely separated and the giant nerve fibres are particularly well developed. (7.) The blood system consists of a gut sinus, connected to a ventral vessel by paired ring vessels in each segment. From the ring vessels branches supplying the various organs of each segment arise. The capillaries of these vessels end blindly. Movement of the blood is effected by rhythmic peristaltic contractions of the walls of the vessels. Details of the circulation are described. When the animal retracts within the tube the blood circulation stops. This reversible stoppage of the blood is brought about by the accumulation of carbonic acid. The course of the respiratory currents within the tube is described. (8.) The ciliary feeding mechanism of the crown is described, the food consisting of finely divided plankton and detritus. (9.) The form of the tube is extremely variable. It is shown to be composed of a glyco-protein of a mucoid nature in which crystals of calcium carbonate in the form of aragonite are deposited. ...