Iwasaki's snail-eater explained

Iwasaki's snail-eater (Pareas iwasakii) is a species of snake in the family Pareidae. The species is endemic to the Yaeyama Islands in the southern Ryukyu Islands, Japan.

Etymology

The specific name, iwasakii, is in honor of Japanese meteorologist Takuji Iwasaki.^[1]

Habitat

The preferred natural habitats of P. iwasakii are forest, shrubland, and grassland.

Ecology

P. iwasakii is a snail-eating specialist;^[2] even newly hatched individuals feed on snails.^[3] It has asymmetric dentition on its jaws, with more teeth on the right mandible (about 25 teeth compared to 15 teeth on the left mandible) which facilitates feeding on snails with dextral (clockwise coiled) shells.^[4] A consequence of this asymmetry is that P. iwasakii is much less adept at preying on sinistral (counterclockwise coiled) snails.^[5] It systematically directs its attack on snails from the right in order to insert its lower jaw into the shell opening.

The selection pressure of this predator on snails of the genus Satsuma has led to a significant increase in the proportion of snails with left-facing shells, known as levogyres, compared to snails with right-facing shells, known as dextrogyres, because the two forms have difficulty mating with each other. This proportion is a local originality, the levorotatory form being very rare on a worldwide scale.

Reproduction

P. iwasakii is oviparous.

Taxonomy

Originally described as the subspecies Amblycephalus formosensis iwasakii by Moichirō Maki,^[6] it was placed in the genus Pareas and elevated to the species P. iwasakii by Tetsuo Takara in 1962.^[7]

Further reading

• Goris, Richard C.; Maeda, Norio (2004). Guide to the Amphibians and Reptiles of Japan. Malabar, Florida: Krieger Publishing Company. 285 pp. .
• 10.1086/591681. 18834301. Divergent Shell Shape as an Antipredator Adaptation in Tropical Land Snails. 2008. Hoso. Masaki. Hori. Michio. species:Michio Hori. American Naturalist. 172. 5. 726–32. 19259125.
• Ota, Hidetoshi (2000). "Current status of threatened amphibians and reptiles of Japan". Population Ecology 42: 5–9.
• Takara, Tetsuo (1962). "[Studies on the terrestrial snakes in the Ryukyu Archipelago]". [''Science Bulletin of the Division of Agriculture, Home Economics and Engineering, University of the Ryukyus'' ] 9: 1–202. (in Japanese, with an abstract in English). (Pareas iwasakii, new combination).

Notes and References

1. [Bo Beolens|Beolens B]
2. Hoso . M. . Hori . M. . species:Michio Hori . Identification of molluscan prey from feces of Iwasaki's slug snake, Pareas iwasakii . Herpetological Review . 2006 . 37 . 174–176.
3. Hoso . M. . Oviposition and hatchling diet of a snail-eating snake Pareas iwasakii (Colubridae: Pareatinae) . Current Herpetology . 26 . 41–43 . 2007 . 10.3105/1345-5834(2007)26[41:OAHDOA]2.0.CO;2 . 83645579.
4. Hoso . Masaki . Asami . Takahiro . species:Takahiro Asami . Michio Hori . Right-handed snakes: convergent evolution of asymmetry for functional specialization . Biology Letters . 2007 . 3 . 169–173 . 10.1098/rsbl.2006.0600. 17307721. 2375934. 2.
5. Hoso. Masaki . Kameda . Yuichi . species:Yuichi Kameda . Wu . Shu-Ping . species:Shu-Ping Wu . Asami . Takahiro . Kato . Makoto . species:Makoto Kato . Hori . Michio . A speciation gene for left-right reversal in snails results in anti-predator adaptation . Nature Communications . 2010 . 1 . 9 . 133 . 10.1038/ncomms1133 . 21139578 . 3105295. 2010NatCo...1..133H .
6. Maki . M. . species:Moichirō Maki . A new subspecies, Amblycephalus formosensis iwasakii, belonging to Amblycephalidae Ishigaki-jima . Transactions of the Natural History Society of Formosa . 1937 . 27 . 217–218.
7. Ota. Hidetoshi . Lin . Jun-Tsong . species:Jun-Tsong Lin . Hirata . Toru . species:Toru Hirata . Chen . Szu-Lung . species:Szu-Lung Chen . Systematic review of colubrid snakes of the genus Pareas in the East Asian islands . Journal of Herpetology . 1997 . 31 . 1 . 79–87 . 1565332 . 10.2307/1565332.