DIPNOI FISHES
FIRST YEAR SECOND SEMESTER
B.L.P.LATHA Lecturer in Zoology SVCR Govt Degree College Palamaner Chittoor Dipnoans (Lungfishes)
The name Dipnoi (Greek : Di-Two Pnoe –breathing) means double breathers, as they respire through gills as well as lungs. There are commonly called as the lung fishes and also described as living fossils. Romer described them as uncle of Amphibians. Lungfishes are all freshwater forms, placed in their three families. They are Australian lungfish - family Ceratodontidae - Neoceratodus. South America lungfish - family Lepidosirenidae – Lepidosiren. African lungfishes -family Protopteridae – Protopterus. In their "lung" is a modified Air bladder swim bladder, which in most fishes is used for buoyancy in swimming, but in the lungfishes also absorbs oxygen and removes waste. All lungfish demonstrate an uninterrupted cartilaginous notochord and an extensively developed palatal dentition. These are best examples of Discontinuous Distribution. Neoceratodus The Australian lungfish lives in fresh water, is also known as the Queensland lungfish. It is example of Discontinuous distribution. The Australian lungfish is the presence of a single dorsal lung and gills. It is primarily nocturnal, and is essentially carnivorous. Australian lungfish is olive-green to dull brown on the back, sides, tail, and fins, and pale yellow to orange on the underside. The lungfish can grow to a length of about 150 cm (4.9 ft), and a weight of 43 kg It has a reddish colouring on their sides which gets much brighter in the males during the breeding season (this colouration is the only distinguishing sexual characteristic). It has stout, elongated body and flattened head with small eyes. The body of the lungfish is covered with large, bony scales. It has powerful diphycercal tail ,long and paddle-shaped. Neoceratodus
The lungfish is reputed to be sluggish and inactive, but it is capable of rapid escape movements with the use of its strong tail. The mouth is small and in a sub terminal position.[ It has five pairs of gills and fins which resemble flippers and Air bladder is single (Monopneustia). It has ten rows occur on each side, grading to small scales on the fins. The skeleton of the lungfish is partly bone and partly cartilage. The vertebrae of the lung fish are pure cartilage, while the ribs are hollow tubes filled with a cartilaginous substance Kidneys are more elongated. It is a oviparous, spawns from August until November, eggs are most abundant during September and October. The lungfish does not necessarily spawn every year. A good spawning season occurs usually once every five years, regardless of environmental conditions. The newly laid egg is hemispherical, delicate, heavily yolked. Adult has a high survival rate and are long-lived (at least 20–25 years). . Reference :-Wikipedia. org/wiki/Australia lungfish. Diagram of Neoceratodus Protopterus
Protopterus is the genus of four species of Lung fish found in Africa, and are carnivorous. Protopterus is the one genus in the family Protopteridae. African lungfishes are generally inhabit shallow waters, such as swamps and marshes and also found in larger lakes such as Lake Victoria. It is elongated, eel-like fishes, with thread- like pectoral and Pelvic fins, can either swim like eels or crawl along the bottom by using their pectoral and pelvic fins and fin rays are absent. The dorsal and caudal fins(Diphycercal) are fused into a single structure. The body has covered soft cycloid scales. It can live out of water for many months in burrows of hardened mud beneath a dried stream bed. Presence of four pairs of gill slits and airbladder (lung) double (Dipneustia). Kidneys are not so elongate. Protopterus African lungfishes breed at the beginning of the rainy season. They construct nests or burrows in the mud to hold their eggs, which they then guard against predators. Larva has four pairs of apparent external gills. Lepidosiren
• It lives in freshwater, found in swamps of Amazon and paraguay basin of South America. • It is the example of Discontinuous Distribution. • It aestivates during the dry season in borrows, constructed for the purpose. The entrance of the burrow is plugged with a mud stopper ventilated by several round holes. • The immature lungfish is spotted with gold on a black background, in the adult, this fades to a brown or gray color. • It is elongated, eel-like fishes with about four feet in length. • I t has very small of cycloid scales • It has five pairs of gill slits. • The Pectoral fins are thin and thread-like, while the pelvic fins are somewhat larger, and set far back. The fins are connected to the shoulder by a single bone and fin rays are reduced. • Presence of air bladder (Lungs) double ( Dipneustia ). • During breeding season the pelvic fins of the male develop accessory gills. • Kidneys are not so elongate . • Larva has four pairs of external gills. Lepidosiren
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