Labyrinth
The Vital Organ
The structure known as the labyrinth consists of a number of concentrically
arranged bony plates covered by a layer of folded skin located on either side of
the gill chamber. The plates are attached to a bony base which is itself
connected to the upper end of the fourth gill-arch.
The membranous covering, which is of vascular nature, that is to say
possessing many small blood vessels, is supplied with blood by an offshoot of
the fourth afferent branchial artery. The outward conveying blood vessel for the
organ is attached to the dorsal aorta.
The interior of the labyrinth is kept constantly moist. This is essential to
enable the vital respiratory gaseous exchange to take place, a function possible
only when in solution. This basic fact applies to any breathing apparatus, be it
labyrinth, lung or gill.
As the fish breaks the water surface a gulp of air is taken in and
automatically pressed into the labyrinth organ. The numerous surface blood
vessels facilitate the gaseous exchange where oxygen is absorbed directly into
the blood stream and carbon dioxide waste expelled. The de-oxygenated air being
released as a single bubble.
It is worth remembering in this connection, that although these air breathing
Labyrinth fishes will not necessarily become distressed or suffocate in
overcrowded or poor quality aquarium conditions in the manner of other species,
they do also make use of gills in conventional fashion, extracting quite high
levels of oxygen from the water.
The significance of this being, that I have in the past come across
fishkeepers who have introduced labyrinths to an already overpopulated and
consequently oxygen depleted aquarium, in the belief that because of their
unique air breathing capabilities no harm will result.
The truth of the matter is, of course, that in all probability no harm will
come to the labyrinths themselves! But what about the other community members
that do not have the luxury of an auxiliary breathing system to fall back on?
They are likely to succumb quickly to the rapidly deteriorating conditions!
Allowing the absorption of oxygen from atmospheric air is not the labyrinth
organ_s only function. With some exceptions, at spawning time members of the
Anabantoidei family build intricate nests consisting of countless tiny
mucus-covered bubbles into which their eggs are deposited. The labyrinth is also
instrumental in this process!
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