R. grylio reaches a length of up to 165 mm. It has a green to dark brown dorsum scattered with irregular dark markings. The throat and ventral and posterior surfaces of the hind legs can be heavily mottled, or the venter may be immaculate. It has no dorsolateral folds, but it does have a pointed snout, fully webbed toes, and a fourth toe which is only slightly longer than the adjacent toes. The young have dorsolateral stripes like Rana virgatipes.

Its range is comprised of the Coastal Plain from the Santee River, South Carolina to Galveston Bay Texas, and includes all of Florida.
R. grylio occurs in standing water.

Southeastern US, ranging from eastern Texas to south central South Carolina, extending south into peninsular Florida (npwrc 1999)

Biogeographic Regions: nearctic (Native )

endemic to a single nation

Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) Southern South Carolina to southern Florida, west to southeastern Texas (Conant and Collins 1991). Introduced on Great Bahama Bank (Schwartz and Henderson 1991). Introduced and well established in northern Puerto Rico (Rios-Lopez and Joglar 2000).

The pig frog ranges in length from 3.25 to 5.5 inches. Their appearance is that of a "bullfrog" with a rather narrow and pointed head and fully webbed hind feet. The fourth toe is webbed nearly to its tip. Pig frog coloration is olive to blackish brown with scattered dark spots. Its venter is white or pale yellow with a pattern that is the colors brown, dark gray and black woven into a net on the thighs. The thighs also have a light line or a row of light spots running across their rear. The Pig frog has no dorsalateral ridges (Conant and Collins 1998). In this frog, the tibia is the same length as the femur. Their eyes are greatly elevated and unusually large, with only a narrow space between them. Nostrils are prominent in Lithobates grylio. They have an elevated fold of skin over the ear that runs to the shoulder, and the ear is orange-brown in color with a green center. The middle and posterior back may have four longitudinal bands of bright orange-brown, alternating with bands of olive (Dickerson 1931).

Pig frogs are sexually dimorphic in size and coloration. Males and females have similar growth rates until the snout-vent length reaches about 100mm. After that, the females grow faster and will eventually reach a larger size than the males (Wood 1998). The male's ear is greatly larger than its eye, whereas the female's ear is equal in size to the eye. Perhaps the most distinguishing characteristic is that males have a bright yellow throat (Dickerson 1931).

Mature tadpoles are very colorful. They have a yellow belly with prominent reticulation on brownish black. Their sides have yellow spots that are encircled by a pinkish color. From the throat region to the pectoral region is clear black and across the pectoral region is green. The yellow spots surrounded by pink continue down the tail in various patterns (Wright 1932).

Length: 16 cm

• Terrestrial
• Freshwater

Generally, these frogs are distributed in most waterways, such as rivers, streams, lakes, ponds, swamps and marshes (Bartlett 1999). The pig frog inhabits the open centers of cypress ponds, which are an extension to, or separation from the prairies. They prefer ponds with the following vegetation types: waterlilies, hard heads, never wets, wampee, watershield, bladderworts, floating hearts, pickerel weed, saw grass, and maiden cane (Wright 1932).

Aquatic Biomes: lakes and ponds; rivers and streams

Comments: Permanent lakes, ponds, swamps, marshes, and streams; especially those with abundant emergent or floating herbaceous vegetation; old rice fields and rice field reservoirs. Occurs in mangroves in the Bahamas (Schwartz and Henderson 1991). Eggs and larvae develop in permanent bodies of water. In South Carolina, males moved from cypress-hardwood zone to grass-herb zone 40-50 m from shore during breeding period; females in grass-herb zone were ready to ovulate (Lamb 1984). When calling, males float in water.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

The Pig frog is mainly active at night and does most of its feeding at this time. Its primary diet consists of insects and crustaceans (Capula 1989).

Comments: Metamorphosed individs. eat various small animals, especially insects and crayfish. Males feed infrequently during breeding season (Lamb 1984). Larvae probably eat suspended matter, organic debris, algae, plant tissue, and small invertebrates.

Comments: Chorusing typically is nocturnal (Lamb 1984).

Little appears to be known about the reproduction of Pig frogs. Published observations are based on very few cases.

Immense choruses of Lithobates grylio erupt at night, when the vast majority of the mating occurs. Rainy, overcast or humid overcast weather seems to provide conditions that make for active mating. Breeding season is thought to begin in late May and continue through to August. They breed when the air is humid with temperatures ranging from 63-78 degrees.

The egg laying process is probably similar to that of the bullfrog (Rana catesbeiana) (Wright 1932).

After mating, approximately 10,000 eggs are laid (Bartlett 1999). The eggs are usually attached to pickerel weed stems in the middle of the pond or on the islands of a cypress pond. They can be found amongst saw grass, maiden cane, and wampee. The eggs, which are small and bead-like, are laid in large masses on the surface of the water. The hatching period is 2-3 days. These eggs appear to have no animal predators; their only threat is the receding water (Wright 1932).

Tadpoles are quite large (100mm), with extremely long tails. Although uncertain, Wright speculates that Lithobates grylio may go through metamorphosis after one year. Bartlett (1999) comments that tadpoles in the northern range of this species reportedly take longer than one year to metamorphose whereas those in the southern part of the range develop in less time. After transformation, the young frogs will remain in the same habitat as adults (Wright 1932).

Lays clutch of up to about 10,000 eggs, March-September (gravid females found April-July in South Carolina). Eggs hatch in several days. Aquatic larval stage lasts 1-2 years.

No special status known.

CITES: no special status

IUCN Red List of Threatened Species: least concern

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Intrinsic Vulnerability: Moderately vulnerable

Environmental Specificity: Broad. Generalist or community with all key requirements common.

Pig frogs are hunted for human consumption, as a source of frog legs.