Adult worms live in the posterior gut of the aquatic larval stage, or tadpole, of an anuran host.
G. batrachiensis is unique in the sense that it produces two different types of eggs to reproduce and that the parasite occurs only in the tadpole stage of its host.
In some species, including Gyrinicola batrachiensis, eggs are deposited early into development and reach the infective stage only after passing through the feces of the host.
In G. batrachiensis, female worms tend to be didelphic, possessing a reproductive tract with two separate branches to allow for the production of each kind of egg.
In this state, which is typically uncommon among G. batrachiensis, they possess a single uterus that produces thick-shelled environmentally resistant eggs that are then shed from the host.
An individual female can colonize a host if she can last long enough to mate and produce offspring with parthenogenetically birthed sons.
[2] Through experimental evidence it has been determined that larvae in infected tadpoles must have developed from autoinfective thin-shelled eggs deposited by the introduced females.
[2] From this information we can conclude with relative certainty that the G. batrachiensis production of two types of eggs offers the maximum chance of survival for the species.
However, a few types of species from amphibians and lizards are known to produce two types of eggs: a thick shelled variety that must pass to the external environment - in order to complete the life cycle - and a thin-shelled variety that gives rises to an endogenous cycle, autoinfection.
Female biased broods are favored, involving mother-son matings and accessibility to haplodiploids.
Colonization is accomplished by immature stages and female bias is favored at low colonization densities by the fact that, unlike isolated males, isolated females are not lost to the gene pool because they can mate with their parthenogenetically produced sons.
Using, in pinworms, mother-son matings are not expected to occur commonly in this life cycle since a female's progeny must leave the host.
However, in G. batrachiensis, a second mode of reproduction has developed that makes mother-son matings possible: the method by which females produce two types of eggs, thin and thick shelled, as explored in detail in the earlier sections of this article.
Hence, early colonists may often reach reproductive maturity in isolation from others of the opposite sex even though, by the end of the colonization period, hosts typically contain a dozen worms.
It is known to occur in 8 anuran species: Bufo americanus, Hyla versicolar, Pseudacris triserata, Rana aura, R. catesbeina, R. clamitans, R. pipiens, and R. sylvatica.
These hosts have been found in Eastern Canadian provinces, as well as California, Ohio, and Michigan in the United States.
[3] Recent studies have shown that G. batrachiensis has a significant effect on the developmental rates of their tadpole hosts.
Some of the proposed manners by which this phenomenon may be explained are: However, at the time of metamorphosis, infected bullfrogs had the same body size and appearance as uninfected bullfrogs, suggesting that the parasite has little impact on the physical morphology of its host (other than the shortening of development time).