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Contains articles and advice on a wide variety of frog species. Answers and addresses questions on species husbandry, captive status, breeding, news and conservation issues concerning frogs.

Chemicals (pesticides, Atrazine, gonadotrophin) and Their Effects on Frog and Fish Sexuality and Reproduction

download (2)Amphibians and fish are highly susceptible to even minute amounts of foreign chemicals in their habitats. As such, their current population declines should serve as an important “early warning signal”, forecasting problems that will eventually affect other animals and ourselves.

An odd twist to this sensitivity issue among frogs is that an injection of gonadotrophin, a human growth hormone, brings many species into breeding condition. This discovery was a boon to captive breeding programs, as most frogs require the duplication of certain environmental cues – dry or wet seasons, for example – if they are to breed normally. However, things can easily go wrong – while using hormones to stimulate breeding, I and others have noted that some male frogs began to develop organs resembling ovaries.

Now, male frogs in the wild are being found to have inter-sex characteristics, including immature eggs within the testes. A recent Harvard University study found such characteristics in 21% of the male green frogs, Rana clamitans, in ponds in suburban Connecticut. It seemed that the affected frogs were more common in suburban than agricultural areas, but other studies have yielded opposite results. Similar reproductive system changes have been documented among catfish in Africa, sturgeon in the Mississippi and other fishes.

Drainage_nitrates_vers_HondeghemFr_2003_04_09Pesticides, the herbicide Atrazine, and other chemicals commonly found in water and soil have been shown to affect sex hormone development, but much more research needs to be done.

There is a great deal of ongoing research in this important area – please read any related articles that you may come across and write in to share new information.

An article describing research into the effects of Atrazine on amphibians is posted at:http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1247376

An Appetite for Cobras: Huge Bullfrog Meals

Pixie Frog
Those who keep or observe frogs soon learn of their prodigious appetites. Surely the champion Anuran eater must be the African bullfrog, Pyxicephalus adspersus. Native to southern Africa, this brute is a popular pet, and with good reason – captive longevity is said to approach 50 years. Two animals that I know of, kept in separate enclosures by the same person, both expired at age 21, in the same week.

The most memorable “frog-eating footage” I’ve seen focused on African bullfrogs in the Etosha Pan, northern Namibia. One enormous animal swallowed a centipede of at least 10 inches in length, which bit the frog numerous times on the way down. Another frog latched onto an emperor scorpion, which also did its best to make itself a “memorable” meal. But a note I read in an African nature journal tops all – a huge male frog burrowed into an outdoor cage at a South African snake park and was, when discovered, in the process of swallowing his 17th baby spitting cobra!

All of this eating results, as you might imagine, in frogs of impressive proportions – a male at the Fort Worth Zoo measured 10 inches from snout to vent and 9 ¾ inches around – a near perfect circle! His weight surely topped 5 pounds, but I do not have the exact figure.
American Bullfrog
Our own American bullfrog, Rana (Lithobates) catesbeianus, offers its African cousin some competition. While working at the Bronx Zoo, it became my habit to toss crickets to the bullfrogs that had colonized a small artificial pond. The frogs became bold in time, and visitors enjoyed the show. On one occasion a bullfrog’s leap for food brought it directly in front of another. The larger animal grabbed the smaller, who was fully three quarters his size and, in front of 50 or so second-graders, proceeded to jam the squirming neighbor down his massive gullet. I observed this fellow thereafter – his noticeably distended abdomen flattened out in two days, after which he again gobbled crickets with enthusiasm!


Male African bullfrogs are diligent parents – they defend the eggs and dig channels to bring water to their tadpoles. You can learn more at:

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