Iwasaki's snail-eater (''Pareas iwasakii)'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

snake Snakes are elongated limbless reptiles of the suborder Serpentes (). Cladistically squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales much like other members of the group. Many species of snakes have s ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Pareidae Pareidae is a small family of snakes found largely in southeast Asia, with an isolated subfamily endemic to southwestern India. It encompasses 42 species in four genera divided into two subfamilies: Pareinae and Xylophiinae. Both families are tho ...

. The species is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the

Yaeyama Islands The Yaeyama Islands (八重山列島 ''Yaeyama-rettō'', also 八重山諸島 ''Yaeyama-shotō'', Yaeyama: ''Yaima'', Yonaguni: ''Daama'', Okinawan: ''Yeema'', Northern Ryukyuan: ''Yapema'') are an archipelago in the southwest of Okinawa Pref ...

in the southern

Ryukyu Islands The , also known as the or the , are a chain of Japanese islands that stretch southwest from Kyushu to Geography of Taiwan, Taiwan: the Ryukyu Islands are divided into the Satsunan Islands (Ōsumi Islands, Ōsumi, Tokara Islands, Tokara and A ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

Etymology

The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

, ''iwasakii'', is in honor of

Japanese Japanese may refer to: * Something from or related to Japan, an island country in East Asia * Japanese language, spoken mainly in Japan * Japanese people, the ethnic group that identifies with Japan through ancestry or culture ** Japanese diaspor ...

meteorologist A meteorologist is a scientist who studies and works in the field of meteorology aiming to understand or predict Earth's atmosphere of Earth, atmospheric phenomena including the weather. Those who study meteorological phenomena are meteorologists ...

Takuji Iwasaki was a Japanese meteorologist, biologist, ethnologist historian. He was a meteorologist at the Ishigaki Weather Station, Ishigaki, Okinawa Prefecture. Initially, when weather forecasting was in its infancy, he had been badly criticized by local p ...

Habitat

The preferred natural

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

s of ''P. iwasakii'' are

forest A forest is an ecosystem characterized by a dense ecological community, community of trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, ...

shrubland Shrubland, scrubland, scrub, brush, or bush is a plant community characterized by vegetation dominance (ecology), dominated by shrubs, often also including grasses, herbaceous plant, herbs, and geophytes. Shrubland may either occur naturally o ...

, and

grassland A grassland is an area where the vegetation is dominance (ecology), dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes such as clover, and other Herbaceo ...

Ecology

''P. iwasakii'' is a snail-eating specialist; even newly hatched individuals feed on snails. It has asymmetric dentition on its jaws, with more teeth on the right

mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

(about 25 teeth compared to 15 teeth on the left mandible) which facilitates feeding on snails with dextral (clockwise coiled) shells. A consequence of this asymmetry is that ''P. iwasakii'' is much less adept at preying on sinistral (counterclockwise coiled) snails. 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 Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

Satsuma Satsuma may refer to: * Satsuma (fruit), a citrus fruit * ''Satsuma'' (gastropod), a genus of land snails Places Japan * Satsuma, Kagoshima, a Japanese town * Satsuma District, Kagoshima, a district in Kagoshima Prefecture * Satsuma Domain, a ...

'' 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 Oviparous animals are animals that reproduce by depositing fertilized zygotes outside the body (i.e., by laying or spawning) in metabolically independent incubation organs known as eggs, which nurture the embryo into moving offsprings kno ...

Taxonomy

Originally described as the

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

''Amblycephalus formosensis iwasakii'' by Moichirō Maki, it was placed in the genus ''

Pareas ''Pareas'' is a genus of Asian snakes in the family Pareidae. All species in the genus ''Pareas'' are harmless to humans. Species ''Pareas'' contains the following species: (''Pareas menglaensis'', new species). (''Pareas kaduri'', new species ...

'' and elevated to the species ''P. iwasakii'' by Tetsuo Takara in 1962.

Etymology

Habitat

Ecology

Reproduction

Taxonomy

References

Further reading