Summary
Physical Description
Size
Description
Identification resources
Distribution and Ecology
Local distribution and microhabitat
Biogeographical distribution
Life History & Behaviour
Behaviour and locomotion
Reproduction
Feeding
Respiration
Anatomy & Physiology
External Morphology
Internal Anatomy
Evolution & Systematics
Fossil History
Phylogenetics
Conservation & Threats
References & Links
Reference List | Respiration
Acanthochitona sp. like other polyplacophorans respires by the use of gills. They have several pairs of gills (known as ctenidia) that are bipectinate, meaning they have two rows of gill filaments (Ruppert et al 2004). These gills are found laterally in the mantle cavity, in the pallial groove, which separates the foot from the mantle (Schwabe 2010). The number of gills has been found to be highly variable even within a genus (Schwabe 2010). The gills are cone shaped and they hang from the roof of the papillae groove, dividing the mantle cavity into the inhalant and exhalant chamber (Ruppert et al 2004). The gill surface known as the lamellae, have a ciliated epithelium which creates a current and brings water through an anterior opening called the inhalant aperture and water passes across the gills and moves posteriorly and passes out the exhalant aperture (Kaas et al 1998, Ruppert et al 2004). Gas exchange occurs between the flowing water and blood in the gill filaments and the high surface area of the gills and thin epithelium of the filaments, facilities efficient respiration.
Acanthochitona sp. gills are merobranchial and abanal, as this gill morphology is characteristic within the suborder Acanthochitonina and the family Acanthochitonidae (Gowlette-Holmes 1998, Okusu et al 2003)(Figure 1). Abanal arrangement is when the gills are found before the anus with only one ctenidia occurring after the nephridopore and new gills occur anteriorly only (Kaas et al 1998, Schwabe 2010). Merobranchial arrangement is where the gills are restricted to the posterior part of the papillae groove (Schwabe 2010).
Figure 1: Acanthochitona sp. merobranchial and abanal gills in the pallial groove, adapted from Kaas et al 1998.
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