Physiology of the accessory respiratory organs of the teleost, Clarias lazera (C. & V.)

Abstract

E g y p t ELEVEN FIGURES JNTRODIJCTTONThe vast majority of fishes are incapable of living f o r any length of time out of water. A few fish, however, are remarkable for being ablc to live out of their aquatic media for a comparatively long time, and also for their peculiar habit of going on excursions over surrounding marshy lands. These fishes usually possess special accessory air-breathing organs wliicli enable them to stay out of water. These organs arc generally met witli where the gill-filaments are reduced. Thus iii Amphipnous (Arnphipnoidae) there is a pharyngeal "lung" for breathing atmospheric air (Das, '27) ; whilc in Periophtlialrrius (Gobiidae ) aerial iwqiiration is pcrformed mainly by tlic pharyngeal diverticula assisted by both buccal and opcrcular cavitics. (Ilas, '40). Acccwory air-breathing organs are also found jn the Ophiocephalidae, Cllariidac, Ana-1)aiititlae and others in which the gill-apparatus is as complrtcl AS in ordinary fishes (Das, '27, '40 ; Moussa, '56). 111 a previous paper the author (Moussa, '56) lias described the accessory respiratory organs of Clarias lazera as consisting of a suprabraiichial chamber-on each side of the hody--c.~iclosing two highly vascular arborcsccnt organs surmounting the epibranchials of the second and 4th branchial arches. The suprahranchial cliambcr lies postero-dorsal to the opercular cavity and its outer \\.all is supported by four 419 420 TOHAMY A. MOUSSA branchial fans formed by the coalescence of the hranchial filaments at the distal end of the ceratobranchial of the first four gill-arches. The fans separate the suprabranchial chamber (air-chamber) from the opercular cavity proper. Between the second and third fans there is a notch which allows air to escape from the pharynx into the air-chamber when the mouth is widely opened for a gulp of air; thus the notch serves as an air-entrance. There is aiiotlier notch lying between the third arid fourth fans and connecting the air-charnbt?r with the opercular cavity; this is used as an air-exit when the operculum is raised.Each of the suprahrancliial air-charnlwrs is supplied by all afferent branchial vessels ; tlie oxygenated blood is conveyed by a separate vessel directly to the latcAral aorta; a condition which is absent in otliei-fishes. The anterior and posterior arborescent organs a r e supplied by the second and 4th afferent branchial vessels respectively ; the equivalent efferent vessels convey the oxygenated ldoocl to both the latc~a l aorta and the dorsal aorta respectively ; a n arrangement which has not been described before ill Clariitlae. l h c arboresceiit organs, charnlwix and fans are highly vascular and, therefore, very likely to be respiratory in function. So, iii this present contribution some cxpcrinieiits have been carried out by the author to t r y to untlerstaiicl more clearly the function of these organs. The experinients were carried out in the laboratory on specimens of Clarias lazcra obtained from the hiahmoudia Canal which supplies Alexandria with fresh water. They were kept ...

The ability of Clarias lazera (Pisces) to survive without air breathing

“…at 25-26°C respectively). These findings contradict Moussa's (1957) suggestions. The following work was therefore carried out to elucidate the respiratory behaviour of this air-breathing species.…”

“…Even longer periods of quiescence and lower frequencies of surfacing were common when the oxygen concentration in water had dropped to 1.5-1 -0 mg/l. Moussa (1957) suggested that Clarias Zazera dies, even in high ambient oxygen concentrations, if prevented from surfacing. Results of the present investigation have shown, however, that C. Zazera can survive without surfacing in water saturated with air.…”

“…These contain two highly vascularized arborescent organs which surround the epibranchial arteries of the second and fourth branchial arches. Moussa (1957) pointed out the vital importance of these accessory respiratory organs in the respiratory behaviour of the fish. He found that individual variations occurred; under normal conditions C. lazera measuring 10.5 cm in length the frequency of branchial respiratory movements was about 21 per minute.…”

The morphology of the accessory air‐breathing organs of the catfish, Clarias batrachus: A SEM Study

“…Considerable attention has been paid to air-breathing teleosts for a number of years (Johansen, 1970), with studies on their physiology (Moussa, 1957;Singh & Hughes, 1971 ;Dehadrai, 1962), ecology (Dehadrai & Tripathi, 1976) and morphometrics of the respiratory organs 1974;Hakim et al, 1978). Particular emphasis has also been placed on the structure of the modifications that allow airbreathing, namely the accessory air-breathing organs.…”

“…A number of species have been studied using the light microscope, including Clarias batrachus (Moussa, 1957;Munshi, 1961), Monopterus alba (Liem 1961 ;1967), Ophicephalus striatus and 0. punctatus (Munshi, 1962) and Anabas testudineus (Munshi, 1968). More recently, many of these studies have been extended to the ultrastructural level by the use of the transmission electron microscope (TEM).…”