The northern leopard frog is a fairly large species of frog, reaching about 11 cm (4.3 in) in snout-to-vent length. It varies from green to brown indorsal color, with large, dark, circular spots on its back, sides, and legs.[8] Each spot is normally bordered by a lighter ring. A pair of dorsolateral folds starting from the back of the eye runs parallel to each other down the back. These dorsolateral folds are often lighter or occasionally pinkish in colour. Also, a pale stripe runs from the nostril, under the eye andtympanum, terminating at the shoulder. Theventral surface is white or pale green. The iris is golden and toes are webbed.
Tadpoles are dark brown or grey, with light blotches on the underside. The tail is pale tan.
Two burnsi morphs, a green morph, and a brown morph of the northern leopard frogBrown morph northern leopard frog in a wood chip pile in Iowa
The northern leopard frog has several different color variations, with the most common two being the green and the brown morphs, with another morph known as the burnsi morph. Individuals with the burnsi morph coloration lack spots on their backs, but may or may not retain them on their legs. They can be bright green or brown and have yellow dorsal folds.[9] Albinism also appears in this species, but is very rare. They can also be blue, and this is quite rare also.[10]
Northern leopard frogs have a wide range of habitats. They are found in permanent ponds, swamps, marshes, and slow-moving streams throughout forest, open, and urban areas.[11] They normally inhabit water bodies with abundant aquatic vegetation. In the summer, they often abandon ponds and move to grassy areas and lawns. They are well adapted to cold and can be found above 3,000 m (9,840 ft)above mean sea level. Males make a short, snore-like call from water during spring and summer. The northern leopard frog breeds in the spring (March–June). Up to 6500 eggs are laid in water, and tadpoles complete development within the breeding pond. Tadpoles are light brown with black spots, and development takes 70–110 days, depending on conditions. Metamorph frogs are 2–3 cm (0.79–1.18 in) long and resemble the adult.
This species was once quite common through parts of western Canada and the United States until declines started occurring during the 1970s. Although the definitive cause of this decline is unknown, habitat loss and fragmentation, environmental contaminants, introduced fish, drought, and disease have been proposed as mechanisms of decline and are likely preventing species' recovery in many areas.[8] Many populations of northern leopard frogs have not yet recovered from these declines.
They eat a wide variety of animals, including crickets, flies, worms, and smaller frogs. Using their large mouths, they can even swallow birds and garter snakes. In one case, abat was recorded as prey of this frog.[13] This species is similar to thepickerel frog (Lithobates palustris) and thesouthern leopard frog (Lithobates sphenocephalus).
The northern leopard frog produces specificribonucleases to itsoocytes. Those enzymes are potential drugs forcancer. One such molecule, calledranpirnase (onconase), is in clinical trials as a treatment forpleural mesothelioma andlung tumors. Another,amphinase, has been described as a potential treatment forbrain tumors.[14]
The northern leopard frog is a popular species forin vitro experiments inmuscle physiology andbiomechanics due to the ease of accessibility for investigators in its native range and the ability of thesartorius muscle to stay alivein vitro for several hours. Furthermore, the reliance of the frog on two major modes of locomotion (jumping andswimming) allows for understanding how muscle properties contribute to organismal performance in each of these modes.
Northern leopard frogs occur fromGreat Slave Lake andHudson Bay, Canada, south toKentucky andNew Mexico, USA.[22][23] It is also found inPanama, where it is endemic to the central cordillera and western Pacific lowlands, although this is most likely an undescribed species.[1] They occupy grasslands, lakeshores, and marshes.
^Frost, D.-R.; et al. (2009). "Response to the Point Of View of Gregory B. Pauly, David M. Hillis, and David C. Cannatella, by the Anuran Subcommittee of the SSRA/HL/ASIH Scientific and Standard English Names List".Herpetologica.65 (2):136–153.doi:10.1655/09-009R1.1.S2CID55147982.
^Stebbins, R.C. (1985).A Field Guide to Western Reptiles and Amphibians. Second Edition. Houghton Mifflin Company, Boston, Massachusetts.
^Conant, R. and Collins, J.T. (1991).A Field Guide to Reptiles and Amphibians: Eastern and Central North America. Third Edition. Houghton Mifflin Company, Boston, Massachusetts.
Ankley GT, Tietge JE, DeFoe DL, Jensen KM, Holcombe GW, Durhan EJ, Diamond SA. (1998). "Effects of ultraviolet light and methoprene on survival and development ofRana pipiens ".Environmental Toxicology and Chemistry17 (12): 2530-2542. (abstract)*Hillis DM (1988). "Systematics of theRana pipiens Complex: Puzzle and Paradigm".Annual Review of Ecology and Systematics.19 (1):39–63.Bibcode:1988AnRES..19...39H.doi:10.1146/annurev.es.19.110188.000351.JSTOR2097147.
Hillis, David M.; Frost, John S.; Wright, David A. (1983). "Phylogeny and Biogeography of theRana pipiens Complex: A Biochemical Evaluation".Systematic Zoology.32 (2):132–43.doi:10.1093/sysbio/32.2.132.JSTOR2413277.
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Data related toLithobates pipiens at Wikispecies
Media related toLithobates pipiens at Wikimedia Commons
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