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Image analysis of the burrowing mechanisms of Polyphysia crassa (Annelida: Polychaeta) and Priapulus cudatus (Priapulida)
Author(s) -
Hunter R. D.,
Moss V. A.,
Elder H. Y.
Publication year - 1983
Publication title -
journal of zoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0952-8369
DOI - 10.1111/j.1469-7998.1983.tb02099.x
Subject(s) - peristalsis , biology , anatomy , dilation (metric space) , invertebrate , ecology , geometry , mathematics
The burrowing mechanisms of two soft‐bodied marine invertebrates, Polyphysia crassa (Annelida: Polychaeta) and Priapulus caudatus (Priapulida) were re‐examined and extended utilizing computer image analysis. Predetermined points on sequential photographs of animals burrowing in methylcellulose (an artificial medium of high transparency) were digitized and stored as x, y coordinates from which were calculated segment length, width, and volume in addition to producing real and straightened images of the animal on a plotter. Both species are adapted to soft substrata and both utilize a direct peristaltic wave to advance the body into a cavity or loosened area formed by anterior structures. Polyphysia displaces and loosens the substratum with lateral scraping movements of its anterior six segments (the “head region”) while Priapulus makes a large cavity anteriorly by the forceful eversion and dilation of the praesoma. Unlike Priapulus, Polyphysia utilizes a different method of locomotion when moving on the mud surface as opposed to burrowing, the former involving two direct peristaltic waves at a time and negligible internal pressures resulting in nearly continuous advance. However when burrowing, Polyphysia , like Priapulus , utilizes a single direct peristaltic wave alternating with phasic pressure pulses which advance the animal in step‐wise fashion.