South American Lungfish, Lepidosiren paradoxa
The South American lungfish (Lepidosiren paradoxa) is found in slow-moving waters and swamps of the Amazon, Paraguay, and the lower Parana River basins in South America. This fish is a member of Lepidosirenidae family and is noted for its necessary air-breathing. Little information is known of the South American lungfish. Common names of this species are the Scaly Salamander-fish and the American Mud-fish.
Young South American lungfish are black and spotted with gold. The adult fish fades to gray or brown. Like in all lungfish, its tooth-bearing maxillary and premaxillary bones are fused. South American lungfish have both autostylic jaw suspension and strong adductor jaw muscles. This species has an elongated eel-like body, like the African lungfish. The South American lungfish may reach to be about 4.1 feet in length. While the pectoral fins are thin and threadlike, the pelvic fins are a bit larger, and set farther back. The gills of this fish are considerably reduced and nonfunctional in adults.
Adult South American lungfish are omnivorous. Young lungfish feed on snails, and insect larvae. These fish have mineralized tooth-plates. Lungfish burrow into the mud during the dry season and build a chamber about 12-20 inches down, leaving a few holes for air. This fish produces a layer of mucus to slow its metabolism and seal in moisture during aestivation. The South American lungfish comes out of hibernation and mates during the rainy season. Young lungfish look like tadpoles and have four external gills. Adult lungfish build nests for their young. Male lungfish progress vascularized structures on their pectoral fins that release excessive oxygen into the water which enriches the oxygen in the nest. In about 7 weeks the young lungfish become air-breathing.
Image Credit: OpenCage/Wikipedia (CC BY-SA 2.5)