Lepidosiren paradoxa
South American lungfish

Lepidosiren paradoxa is found in the neotropics of South America, including Argentina, Bolivia, Brazil, Columbia, French Guiana, Paraguay, Peru, and Venezuela (Planquette et al., 1996). (Planquette, Keith, and Le Bail, 1996)

Details of the range of L. paradoxa are difficult to establish (Alves-Gomes et al., 2003). There has not been a lot of research on this species and the specimens that have been identified lack information on their origin. (Alves-Gomes et al., 2003)

Lepidosiren paradoxa live in a subtropical climate with temperatures ranging from 24 to 28°C (Planquette et al., 1996). This species lives in South America, primarily in the Amazon river basin. They prefer stagnant water where there is little current, such as a swamp or lake. These fish typically stay very close to the surface of the water. In times of drought, they can burrow in the mud up to 50 cm to avoid drying out (Berra, 2001). Lepidosiren paradoxa are primarily freshwater fish and are physiologically unable to cross large expanses of saltwater (Alves-Gomes et al., 2003). (Alves-Gomes et al., 2003; Berra, 2001; Planquette, Keith, and Le Bail, 1996)

Lepidosiren paradoxa juveniles have a pattern of bright yellow spots which fade away as the fish matures (Alves-Gomes et al., 2003). Adult South American lungfish have a black or grey coloration. Lungfish have solid toothplates instead of individual teeth. Bodies are long and slender, somewhat like salamanders, with a diphycercal tail. These fish can grow up to 125 cm in length (Baensch et al., 1985).

Lepidosiren paradoxa young look a bit like amphibian larvae, with four external gills that they use for breathing until about seven weeks in age. After this time, they become obligate air breathers and regression of the external gills begins (Berra, 2001). They have a reduced bronchial apparatus which allows them to survive during times when oxygen levels are low. During drought, they can burrow into mud to 50 cm below the surface and become dormant until the environment becomes more hospitable (2001). (Alves-Gomes et al., 2003; Baensch and Riehl, 1985; Berra, 2001)

Surfactant composition of South American lungfish resembles that of amphibians. In contrast, the more primitive Australian lungfish, Neoceratodus fosteri, possesses surfactant that is almost identical to primitive air-breathing actinopterygiian fish (Orgeig, 1995). This could be one reason why L. paradoxa must breathe air as an adult, while other lungfish can breathe air or water. (Orgeig and Daniels, 1995)

Newly hatched Lepidosiren paradoxa resemble amphibian tadpoles. The have four external gills which they use to breathe for the first seven weeks of their lives (Berra, 2001). After this time, they become strictly air breathers and their gills begin to regress (2001). During the breeding season, the males develop gill-like structures that allow them to release oxygen into their burrows for their developing young (2001). These structures disappear after the breeding season is over. (Berra, 2001)

Lepidosiren paradoxa has not been well studied in terms of life span, but the studies that have been conducted show that the average lifespan of this species is a little more that eight years, both in the wild and in captivity. (Max Planck Institute for Demographic Research, 2005)

Lepidosiren paradoxa is a solitary species. They live by themselves in burrows that they construct in swamps or lakes (Alves-Gomes et al., 2003). They are mostly inactive, laying in the muddy or shallow water close to the surface in order to breathe. Other behaviors, such as social structures and interaction with other species are largely unknown due to the lack of research on this species. (Alves-Gomes et al., 2003)

Home Range

The home range of Lepidosiren paradoxa is likely small because of its inactive nature. (Alves-Gomes et al., 2003)

There is not a lot known about communication and perception in Lepidosiren paradoxa. They have small eyes which suggests that L. paradoxa relies on other senses to detect prey and potential predators.

Lepidosiren paradoxa eat a variety of food items including some bony fish, algae and weeds, terrestrial plants (stems), shrimp, insects, clams, and snails (Berra, 2001). They are primarily carnivorous. Juveniles, which are strictly aquatic, feed on larval insects and snails. (Berra, 2001)

South American lungfish capture prey by suction feeding. They use tooth plates, an enlarged cranial rib (which serves as the site for the origin of the muscle that depresses the hyoid apparatus), and a depressor mandibulae to manipulate and chew food prior to swallowing. Hydraulic transport achieved by movements of the hyoid apparatus is used to position prey within the mouth. This is parallel to the function of a tongue (Bemis, 1986). (Bemis and Lauder, 1986)

Information on the predators of Lepidosiren paradoxa, as well as any predator/anti-predator adaptations are largely unknown due to lack of research on this species.

This species influences the neotropical ecosystem of the Amazon Basin. Lepidosiren paradoxa prey on some small bony fish, shrimp, clams, snails, and insects (Berra, 2001). Any role that they play as a prey item is largely unknown. (Berra, 2001)

There are no known adverse effects of Lepidosiren paradoxa on humans.

This species does not provide direct economic benefits to humans. It does provide intellectual benefits; lungfish represent an important step in vertebrate evolution and their origin provide insights into the origin of tetrapods (Alves-Gomes et al., 2003). (Alves-Gomes et al., 2003)

Lepidosiren paradoxa is not listed on the IUCN Red List, CITES appendices, or the U.S. Endangered Species List. The abundance of this fish is largely unknown (Alves-Gomes et al., 2003). (Alves-Gomes et al., 2003)

Lepidosiren paradoxa was the first living species of lungfish to be formally named (Alves-Gomes et al., 2003). There are three living genera of lungfish, Neoceratodus, Lepidosiren, and Protopterus.

Fossil evidence has placed some Devonian lungfish in fully marine habitats as well as freshwater deposits (2003). Lepidosirenids show a clear vicariance pattern that is consistent with the separation of the African and South American continents during the Cretaceous (2003).

Because of their relationship with both fish and tetrapods, lungfish are a very important evolutionary step. More research should be done so that they can be more fully understood. (Alves-Gomes et al., 2003)