An American Bullfrog (Rana catesbeiana) reveals only a heart-shaped head through a carpet of Duckweed (Lemnaceae) completely covering a small pond.
The bullfrog is native to eastern North America with a natural range from the Atlantic Coast to as far west as Oklahoma and Kansas. However, it has been introduced elsewhere where it is considered an invasive species, including Arizona, Utah, Colorado, Nebraska, Nevada, California, Oregon, Washington, Hawaii, Mexico, Canada, Cuba, Jamaica, Italy, Netherlands, France, Argentina, Brazil, Uruguay, Venezuela, Colombia, China, South Korea and Japan. In some areas, the bullfrog is used as a food source.
Bullfrogs are voracious, ambush predators that eat any small animal they can stuff down their throats. Bullfrog stomachs have been found to contain rodents, reptiles, amphibians, crayfish, birds, bats, fish, tadpoles, snails and their usual food – insects. Bullfrogs are able to jump a distance 10x their body length. The female lays up to 20,000 eggs at a time that form a thin, floating sheet which may cover an area of 0.5 -1 m2 (5.4 - 10.8 sq ft). The embryos hatch in 3 - 5 days. Time to metamorphize into an adult frog ranges from a few months in the southern part of their range to 3 years in the north where the colder water slows development. Maximum lifespan in the wild is 8 - 10 years, but one bullfrog lived for almost 16 years in captivity.
Duckweed (Lemnoideae) are small flowering aquatic plants which float on or just beneath the surface of still or slow-moving bodies of fresh water. These plants lack obvious stems or leaves, and depending on the species, each plant may have no root or one or more simple rootlets. Reproduction is mostly by asexual budding, however, occasionally three tiny flowers are produced for sexual reproduction. The flower of the duckweed measures a mere 0.3 mm (1/100th of an inch) long.