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Individual organisms and entire species' ecological interactions are often difficult to define and measure. It is frequently dependent on the scale and context of interactions. Many interactions occur in terrestrial snails within other animals. Such may include other species of snails, predators, and pray (Myers and Burch. 2011). The interactions between snails may either be other being a predator or a worse prey. It may be terrestrial snails are carnivorous and prey on other snails. Most of land snails mostly interact to reproduce. Snails also pray for parasites. Many parasites use snails as an intermediate host, which includes nematodes and mites. Other vertebrates prey on land snails as well. Some of the vertebrates that prey on land snails are turkeys, mice, and turtles. Humans are also a predator of snails. They are harvested by humans to eat their visceral mass (Nekola, 2010).

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It is suggested that there are the highest population densities of freshwater snails and anuran tadpoles in ponds of an intermediate size where abiotic disturbance is low and fast predators are absent. It was found out that both snails and tadpoles feed on periphytic algae, and thus there must be a significant potential for competitive interactions to occur between the two distant related taxa. It is examined in the field experiment that the relative strength of competition between two closely related species, gymnasia stagnalis, and L. peregra, and between L. stagnalis and tadpole of the common frog, Rana Temporaria (Myers and Burch. 2011). Snail growth and egg production and tadpole size at the time of metamorphosis were determined. The effects on the common food source periphyton were monitored with the aid of artificial substrates. Periphyton dry weight was dramatically reduced in the presence of snails and tadpoles. There were no competitive effects on the growth of egg production of the two snail species when they were co-existing. There was a 95% mortality of L. Pereira, which was high after reproduction, but independent of treatment. L. stagnalis growth was reduced only at the highest tadpole densities, where egg production was reduced both by intraspecific competition and by competition with tadpoles. After tadpole metamorphosis, differences in egg production were retained. Tadpole larval period increased the weight of metamorphosing frogs decreased, and the growth rate was reduced as a function of increasing tadpole density. Contrary to expectation, however, there were positive effects of snails on tadpole larval period, weight, and growth rate. Further, in experimental containers without snails, there was a dense growth of the filamentous green algae cladophara.

We suggest that snail facilitative effects on tadpoles are due to indirect interaction mechanisms involving competition between food sources of different quality and tadpoles being competitively dominant over snails for a preferred food source. Snails will be forced to feed on low quality cladophora in the presence of tadpoles, increasing nutrients turnover rates, which results in enhanced productivity of microalgae, increasing tadpole food resources; thus, there are negative effects on snails because they experience resource depression (Nekola, 2010).

References

Myers, p., and Dr. J.B. Burch. 2011. http://animal diversity. Ummz.umich.edu/site/accounts/information/Gastropoda.html

Nekola, J.C., 2010. Acidophilic gastropod communities of North America. Journal of molluscan studies vol. 76. Issue 2:144-156