''Hydrophis semperi'', commonly known as the Lake Taal snake, Garman's sea snake, the Philippine freshwater sea snake, and the Luzon sea snake, is a rare

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 ...

venomous Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...

sea snake Sea snakes, or coral reef snakes, are elapid snakes that inhabit marine environments for most or all of their lives. They belong to two subfamilies, Hydrophiinae and Laticaudinae. Hydrophiinae also includes Australasian terrestrial snakes, wher ...

found only in a single lake on the island of

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 ...

in the

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 is noted for being one of two known species of sea snakes that are known to be found almost-exclusively in freshwater. The other freshwater sea snake

is '' Laticauda crockeri.

Etymology

The specific name, ''semperi'', is in honor of German

zoologist Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the Animal, animal kingdom, including the anatomy, structure, embryology, evolution, Biological clas ...

Carl Gottfried Semper.Beolens, Bo; Michael Watkins; Michael Grayson (2011). ''The Eponym Dictionary of Reptiles''. Baltimore: Johns Hopkins University Press. xiii + 296 pp. . (''Hydrophis semperi'', p. 240).

Taxonomy

''H. semperi'' is classified with the rest of the "true" sea snakes in the

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

Hydrophiinae Hydrophiinae is a subfamily of venomous snakes in the family Elapidae. It contains most sea snakes and many genera of venomous land snakes found in Australasia, such as the taipans (''Oxyuranus''), tiger snakes (''Notechis''), brown snakes (' ...

of 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 ...

Elapidae Elapidae (, commonly known as elapids ; grc, ἔλλοψ ''éllops'' "sea-fish") is a family of snakes characterized by their permanently erect fangs at the front of the mouth. Most elapids are venomous, with the exception of the genus Emydoce ...

Description

Like all "true" sea snakes, ''H. semperi'' is a rather heavyset snake, elongated with a small head. It possesses the characteristic flattened, paddle-like tail found in the members of its subfamily. This particular species is considered short in comparison to the rest of the family; adult specimens of ''H. semperi'' that have been caught have a total length (including tail) of . The snake is colored much like a typical sea snake, having a dark blue or black body with narrow yellow (sometimes white) crossbands. Like its close relatives, its nostrils are located almost

dorsally Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

, with valves that prevent water from entering its nasal (and oral) cavities when the snake is submerged.Uetz,Peter. EMBL Reptile Database: Subfamily Hydrophiinae (Sea Snakes). Family Elapidae (cobras, coral snakes, and seasnakes etc.). European Molecular Biology Laboratory (EMBL) Heidelberg 2006-04-04

Habitat and evolution

''H. semperi'' is known to be found only in the waters of

Lake Taal Taal Lake ( tl, Lawa ng Taal, ), formerly known as Bombón Lake, is a freshwater caldera lake in the province of Batangas, on the island of Luzon in the Philippines. The lake fills Taal Volcano, a large volcanic caldera formed by very large e ...

(formerly known as Lake Bombon) in the province of

Batangas Batangas, officially the Province of Batangas ( tl, Lalawigan ng Batangas ), is a province in the Philippines located in the Calabarzon region on Luzon. Its capital is the city of Batangas, and is bordered by the provinces of Cavite and La ...

in the

. The only freshwater sea snake in the country, it lives the entirety of its life within the confines of the lake, feeding and breeding in its slightly acidic waters. The lake itself is a volcanic

crater lake Crater Lake (Klamath language, Klamath: ''Giiwas'') is a volcanic crater lake in south-central Oregon in the western United States. It is the main feature of Crater Lake National Park and is famous for its deep blue color and water clarity. The ...

, which was formerly saltwater but gradually lost its salinity after the lake was closed off from the sea by an eruption in the 16th century. It is this unique aspect of the lake's formation and history that led to the evolution of several once-saltwater species, including ''H. semperi''. Thus, this species is relatively young, having been accustomed to freshwater for less than a millennium.

Diet

As with "true" sea snakes, ''H. semperi'' is

piscivorous A piscivore () is a carnivorous animal that eats primarily fish. The name ''piscivore'' is derived . Piscivore is equivalent to the Greek-derived word ichthyophage, both of which mean "fish eater". Fish were the diet of early tetrapod evoluti ...

, feeding primarily on the numerous fish species that are known to dwell in Taal Lake's murky waters.

Biology

Very little is known about the life history of ''H. semperi'', including its ecology and breeding cycles.

Conservation status

Since so little is known about the reproductive habits of the species ''H. semperi'', there have been virtually no estimates of the snake's population. Like many other species

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 ...

to the lake, it is vulnerable as a species to any anthropogenic effects on the lake's ecosystem, both direct and indirect.

Pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the ...

is always a major issue when it comes to enclosed bodies of water with numerous surrounding human settlements. The numerous commercial establishments, towns and plantations dumping chemicals and sewage into the lake, combined with the dense population of fish farms in the lake's waters may yet have an adverse effect on the health of the species as a whole. In addition, while the snake itself has no commercial value and is not harvested, it suffers from the typical human stigma that is often attributed to snakes. Fishermen that frequently encounter the docile snakes have been known to kill them simply because of what they are.

Etymology

''H. semperi'' was named after

Carl Semper Carl Gottfried Semper (July 6, 1832, Altona, Hamburg – May 29, 1893, Würzburg) was a German ethnologist and animal ecologist. Career Semper attended the Hanover Polytechnic from 1851 to 1854 and achieved a Ph.D. in zoology from the Universit ...

, a German ecologist who discovered the species in the mid-19th century. Locally, the snake is known as ''duhol matapang''.

Etymology

Taxonomy

Description

Habitat and evolution

Diet

Biology

Conservation status

Etymology

References

Further reading