Tomato Frog

About the tomato frog

Tomato frogs are any of three species in the genus Dyscophus, in the family Microhylidae: D. antongilii, D. insularis, and D. guineti. Dyscophus is the only genus in its subfamily, Dyscophinae, and all three species are endemic to Madagascar. The common name comes from the bright red color of D. antongilii.

Adult coloring varies from yellowish orange to deep red. Females are larger than males, reaching up to 4 inches (10 cm) in length, while males top out at 2 to 3 inches (5 to 7.5 cm). Most females run reddish-orange to bright dark red, with bellies that are more yellowish and sometimes marked with black spots on the throat. Males are duller, more of a brownish-orange, and juveniles of both sexes start out dull and brighten as they mature. Frogs reach sexual maturity in 9 to 14 months and can live 6 to 8 years.

Behavior and diet

Tomato frogs are nocturnal and breed during the rainy season. They eat small insects and invertebrates, and their hunting method is unusually precise: when prey is within a narrow angle of the head, the frog aligns its head toward it and projects its tongue rapidly, driven by momentum transferred from the lower jaw and elastic energy stored in the mouth-opening muscles. When prey appears at a wider angle, the frog instead aligns both its head and tongue toward the target and uses a hydrostatic mechanism to extend the tongue, which lets it capture prey across a broader range of angles than the first method allows.

When threatened, a tomato frog puffs up its body. If a predator grabs it in its mouth, the frog's skin secretes a thick substance that numbs the predator's eyes and mouth, forcing it to let go so it can clear its vision. In humans, this secretion occasionally causes allergic reactions, though these are not deadly.

Reproduction is prolific: females lay more than 1,000 eggs during every month of the year except November, with the most reproductive activity occurring from January through May and the least from June through December. Eggs hatch into tadpoles after about 36 hours, and the tadpoles become metamorphs, or froglets, after roughly 45 to 60 days.

Range and habitat

Tomato frogs are endemic to Madagascar, where they are found in the northeast of the island around Antongil Bay, which gives the species its name, antongilii, and south to Andevoranto. They live in moist lowland forest, rivers, swamps, and marshes, and also turn up in ponds, ditches, plantations, rural gardens, and heavily degraded former forest. They breed in shallow pools, swamps, and slow-moving water.

Conservation status

The tomato frog is rated Least Concern on the IUCN Red List, in a 2017 assessment, and it is listed on CITES Appendix II, which regulates international trade.

Numbers have declined in the past because of habitat degradation, pollution, and over-collection of these brightly colored frogs for the pet trade. Collecting was concentrated near the town of Maroantsetra, and the pressure led to the species being placed on CITES Appendix I for a time before its later move to Appendix II. Very little is known about its distribution, behavior, and threats, and further research is needed.