LUNGFISH

any of six species (three species according to some authorities) of air-breathing fishes placed with a number of extinct forms in the subclass Dipnoi (order Dipnoi of some authorities). The Dipnoi first appeared in the Lower Devonian Period (about 370,000,000395,000,000 years ago). The extant species occur in rivers and lakes in Africa, South America, and Australia. They are especially interesting because of their characteristic body forms, their generally large size, their erratic distribution over the tropical regions of the earth, and their peculiar mode of life. any of six species of air-breathing fishes placed with a number of extinct forms in the subclass Dipnoi (order Dipnoi of some authorities). Lungfishes are found in rivers and lakes of South America, Africa, and Australia. The South American lungfish (Lepidosiren paradoxa) and the African lungfishes (four species of Protopterus, considered a single species by some authorities) are placed in the family Lepidosirenidae. The members of this family are slim, elongated, eel-like fishes with small scales and two lungs. The pectoral and pelvic fins are slender filaments and are used by the fishes to sense their surroundings. The South American lungfish grows about 1 m (40 inches) long. The largest of the African lungfishes is P. aethiopicus, a mottled yellow, East African species that may grow about 2 m long. Both the South American and African lungfishes build nests for spawning, and in both instances the nests are guarded by the male. In dry periods, the South American species buries itself in the mud and aestivates (becomes dormant) until water returns. The African species also aestivate, but do so in cocoons that are secreted by their bodies and that harden into leathery cysts. The Australian lungfish (Neoceratodus forsteri), placed in the family Ceratidae, is found in Queensland, Australia. Unlike the other lungfishes, it has a single lung, large scales, and paddle-like pectoral and pelvic fins. It may reach a length of about 1.25 m (49 inches) and a weight of 10 kg (22 pounds). Considered more primitive than the South American and African forms, the Australian lungfish lays its eggs among aquatic plants but does not build a nest and does not aestivate during droughts. Additional reading H. Swan, D. Jenkins, and K. Knox, Metabolic Torpor in Protopterus aethiopicus: An Anti-Metabolic Agent from the Brain, Am. Nat., 103:247258 (1969), an article on dry sleep in lungfishes; M. Blanc, F. d'Aubenton, and Y. Plessis, Mission M. Blanc-F. d'Aubenton (1954) IV. tude de l'enkystement de Protopterus annectens (Owen 1839), Bull. Inst. Fr. Afr. Noire, Series A, 18:843854 (1956), a study of the encystment of Protopterus annectens; P. Brien, M. Poll, and J. Bouillon, Ethologie de la reproduction du Protopterus dolloi (Boulenger), 15th Int. Congr. Zool., sect. 1 (1959); J.S. Budgett, On the Breeding-Habits of Some West-African Fishes, with an Account of the External Features in the Development of Protopterus annectens, and a Description of the Larva of Polypterus lapradei, Trans. Zool. Soc. Lond., 16:115136 (1901); K. Curry-Lindahl, On the Ecology, Feeding Behaviour and Territoriality of the African Lungfish, Protopterus aethiopicus, Heckel, Ark. Zool., Series 2, 9:479497 (1956); A.G. Johnels and G.S.O. Svensson, On the Biology of Protopterus annectens (Owen), ibid., 7:131164 (1955), a detailed study of the habits of lungfishes in the flooding zones on both sides of the Gambia River; K.H. Lueling, Einige Notizen ber afrikanische Lungenfische, Dt. Aquar.-Terrar-Z., 12:1214, 4446 (1959), on the habits and distribution of the African lungfishes, together with a distribution map according to Poll; Untersuchungen an Lungenfischen, insbesondere an afrikanischen Protopteriden, Bonn. Zool. Beitr., 12:87112 (1961), a detailed examination of the experimental encysting of the West African lungfish Protopterus dolloi in captivity; Fische mit Lungen, Neptun, 6:8083 (1966), a study of the morphology, anatomy, and method of breathing of lunglike structures in the Dipnoi; M. Poll, Zoogographie des protoptres et des polyptres, Bull. Soc. Zool. Fr., 79:282289 (1955), a discussion of the distribution of the four species of African lungfishes, with a distribution map; H.W. Smith, Metabolism of the Lung-Fish, Protopterus aethiopicus, J. Biol. Chem., 88:97130 (1930), the first modern physiological study of the encysting of Ethiopian lungfishes in captivity; Observations on the African Lung-Fish, Protopterus aethiopicus, and on Evolution from Water to Land Environments, Ecology, 12:164181 (1931); E.K. Suvorov, Allgemeine Fischkunde (1959; German trans. from the 2nd Russian ed. of 1948), includes a chapter on the breathing organs of Dipnoi.