''Gerarda prevostiana'', commonly known as the cat-eyed water snake, Gerard's water snake, or the glossy marsh snake, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

snake Snakes are elongated, Limbless vertebrate, limbless, carnivore, carnivorous reptiles of the suborder Serpentes . Like all other Squamata, squamates, snakes are ectothermic, amniote vertebrates covered in overlapping Scale (zoology), scales. Ma ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Homalopsidae The Homalopsidae are a family of snakes which contains about 28 genus, genera and more than 50 species. They are commonly known as Indo-Australian water snakes, mudsnakes, or bockadams. They are also known as ''ular air'' (lit. "water snake") in ...

. The species is

endemic Endemism is the state of a species being found 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 found elsew ...

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...

. It is the only species in the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

''Gerarda''.

Etymology

The generic name, ''Gerarda'', is in honor of someone named "Gerard". Unfortunately,

John Edward Gray John Edward Gray, FRS (12 February 1800 – 7 March 1875) was a British zoologist. He was the elder brother of zoologist George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray (1766–1828). The same is used for ...

, who named the genus in 1849, did not specify whom he was honoring. Two possibilities are Adam Gerard or Rev. Gerard R. Smith, both of whom sent specimens of reptiles to Gray at the British Museum.Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). ''The Eponym Dictionary of Reptiles''. Baltimore: Johns Hopkins University Press. xiii + 296 pp. . (Genus ''Gerarda'', p. 99; species ''G. prevostiana'', p. 211). The specific name, ''prevostiana'', is in honor of

French French (french: français(e), link=no) may refer to: * Something of, from, or related to France ** French language, which originated in France, and its various dialects and accents ** French people, a nation and ethnic group identified with Franc ...

naturalist and

illustrator An illustrator is an artist who specializes in enhancing writing or elucidating concepts by providing a visual representation that corresponds to the content of the associated text or idea. The illustration may be intended to clarify complicat ...

Florent Prévost Florent Prévost (1794 – 1 February 1870) was a French naturalist and illustrator. Prévost was assistant naturalist at the Muséum National d'Histoire Naturelle. He was the author of various zoological works, including ''Les Pigeons par Madame ...

Diet

''Gerarda prevostiana'' feeds almost exclusively on

crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...

s, which it tears into bite-sized pieces by pulling them through its coils, in contrast to most other snakes which swallow their

prey Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the ...

whole.

Description

''Gerarda prevostiana'' has the following scalation. The

frontal Front may refer to: Arts, entertainment, and media Films * ''The Front'' (1943 film), a 1943 Soviet drama film * ''The Front'', 1976 film Music *The Front (band), an American rock band signed to Columbia Records and active in the 1980s and ea ...

is a little longer than broad, shorter than its distance from the end of the snout, or than the parietals. The loreal is slightly longer than deep, a little smaller than the nasal. There is one

preocular In scaled reptiles, the ocular scales are those forming the margin of the eye.Wright AH, Wright AA. 1957. ''Handbook of Snakes''. Comstock Publishing Associates (7th printing, 1985). 1105 pp. . The name originates from the term ''oculus'' which ...

, and there are two postoculars. The temporals are arranged 1+2. There are eight

upper labials In reptiles, the supralabial scales, also called upper-labials, are those scales that border the mouth opening along the upper jaw. They do not include the median scaleWright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates ( ...

, the fourth entering the eye. Four of the lower labials are in contact with the anterior

chin shields Chin shields or chinshields, genials scales on a snake are scales found on the underside of the snake's head towards the anterior and touching the lower labial scales. Chin shields to the front of the snake (towards the snout) are called anterior c ...

. The anterior chin shields are much larger than the posterior chin shields. The

dorsal scales In snakes, the dorsal scales are the longitudinal series of plates that encircle the body, but do not include the ventral scales. Campbell JA, Lamar WW (2004). ''The Venomous Reptiles of the Western Hemisphere''. Ithaca and London: Comstock Publis ...

are in 17 rows at midbody. The

ventrals In snakes, the ventral scales or gastrosteges are the enlarged and transversely elongated scales that extend down the underside of the body from the neck to the anal scale. When counting them, the first is the anteriormost ventral scale that cont ...

number 146–158. The

anal Anal may refer to: Related to the anus *Related to the anus of animals: ** Anal fin, in fish anatomy ** Anal vein, in insect anatomy ** Anal scale, in reptile anatomy *Related to the human anus: ** Anal sex, a type of sexual activity involvin ...

is divided. The

subcaudals In snakes, the subcaudal scales are the enlarged plates on the underside of the tail.Wright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates (7th printing, 1985). 1105 pp. . These scales may be either single or divided (pair ...

number 31–34. The body is uniform dark olive above, with three outer rows of scales whitish. The upper lip is white, and the rostral is dark olive. The ventrals and subcaudals are whitish, with dark edges.Boulenger GA (1890). ''The Fauna of British India, Including Ceylon and Burma. Reptilia and Batrachia.'' London: Secretary of State for India in Council. (Taylor & Francis, printers). xviii + 541 pp. (''Gerardia'' ic''prevostiana'', p. 379). The total length is 41 cm (16 inches), including the tail which is 5 cm (2 inches) long.

Geographic range

''Gerarda prevostiana'' is found in coastal areas between western

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

(Mumbai) to eastern

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

; it occurs in India (including the

Andaman Islands The Andaman Islands () are an archipelago in the northeastern Indian Ocean about southwest off the coasts of Myanmar's Ayeyarwady Region. Together with the Nicobar Islands to their south, the Andamans serve as a maritime boundary between th ...

)

Sri Lanka Sri Lanka (, ; si, ශ්‍රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an ...

Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...

Myanmar Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John C. Wells, Joh ...

Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is bo ...

Peninsular Malaysia Peninsular Malaysia ( ms, Semenanjung Malaysia; Jawi: سمننجڠ مليسيا), or the States of Malaya ( ms, Negeri-negeri Tanah Melayu; Jawi: نڬري-نڬري تانه ملايو), also known as West Malaysia or the Malaysian Peninsula, ...

Singapore Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, borde ...

Cambodia Cambodia (; also Kampuchea ; km, កម្ពុជា, UNGEGN: ), officially the Kingdom of Cambodia, is a country located in the southern portion of the Indochinese Peninsula in Southeast Asia, spanning an area of , bordered by Thailand t ...

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

(Borneo:

Sarawak Sarawak (; ) is a States and federal territories of Malaysia, state of Malaysia. The largest among the 13 states, with an area almost equal to that of Peninsular Malaysia, Sarawak is located in northwest Borneo Island, and is bordered by the M ...

), and the Philippines (

Luzon Luzon (; ) is the largest and most populous island in the Philippines. Located in the northern portion of the Philippines archipelago, it is the economic and political center of the nation, being home to the country's capital city, Manila, as ...

Etymology

Diet

Description

Geographic range

References

Further reading