![Pelamis platura yellow form Costa Rica](https://upload.wikimedia.org/wikipedia/commons/0/0c/Pelamis_platura_yellow_form_Costa_Rica.jpg)
The yellow-bellied sea snake (''Hydrophis platurus'') is a
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 ...
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 ...
of snake from the subfamily
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''), Pseudonaja, brown sn ...
(the sea snakes) found in
tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
oceanic waters around the world except for the
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...
. For many years, it was placed in the
monotypic
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...
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 ...
''Pelamis'', but recent molecular evidence indicates it lies within the genus ''
Hydrophis
''Hydrophis'' is a genus of sea snakes, venomous snakes in the subfamily Hydrophiinae of the family Elapidae. Species in the genus ''Hydrophis'' are typically found in Indo-Australian and Southeast Asian waters. Currently, around 36 species are ...
''.
Taxonomy
In 1766,
Linnaeus
Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...
published the original description of the yellow-bellied sea snake, naming it ''Anguis platura'' (''Anguis'' meaning snake). In 1803,
François Marie Daudin
François Marie Daudin (; 29 August 1776 in Paris – 30 November 1803 in Paris) was a French zoologist.
With legs paralyzed by childhood disease, he studied physics and natural history, but ended up being devoted to the latter.
Daudin wrote ' ( ...
created the new
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 ...
''Pelamis'' and assigned this
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 ...
to it, referring to it as ''Pelamis platuros''. In 1842, Gray described what he thought was a new species and called it ''Pelamis ornata'' (subsequently ''P. ornata'' became a synonym of ''P. platura''). The commonly used genus name ''Pelamis'' is derived from the
Ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...
word for "tunny fish", which presumably refers to the habitat or what Daudin thought they ate. The specific name ''platurus'' is a combination of the Ancient Greek words ''platys'' "flat" and ''oura'' "tail", referring to the flattened tail. The word ''Pelamis'' is a feminine noun and means young or small tunny fish. In 1872,
Stoliczka introduced the name ''Pelamis platurus'' (still the most used scientific name by scientists today), but used the incorrect ending ''-us'' instead of ''-a'' which a feminine noun requires. A few recent examples exist of scientists' beginning to use the grammatically correct name ''Pelamis platura'', e.g., Bohme 2003 and the Reptile Database with its page headed ''Pelamis platura'' (Linnaeus, 1766), which includes an extensive synonymy of the different scientific names which have been used for the yellow-bellied sea snake. The same rules apply for the most recent taxonomic name of ''Hydrophis platurus''.
To further complicate the
nomenclature
Nomenclature (, ) is a system of names or terms, or the rules for forming these terms in a particular field of arts or sciences. The principles of naming vary from the relatively informal naming conventions, conventions of everyday speech to the i ...
, the taxonomic status of sea snakes is still under review, with recent authors suggesting a dismantling of
monotypic
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...
genera, such as ''Pelamis'', in favour of a single genus, ''
Hydrophis
''Hydrophis'' is a genus of sea snakes, venomous snakes in the subfamily Hydrophiinae of the family Elapidae. Species in the genus ''Hydrophis'' are typically found in Indo-Australian and Southeast Asian waters. Currently, around 36 species are ...
'', in order to reduce
paraphyly
In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...
and better reflect
phylogenetic relationship
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
s.
Other common names are yellowbelly sea snake or pelagic sea snake.
Evolution
Sea snakes are a
monophyletic
In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...
group (
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''), Pseudonaja, brown sn ...
) that diverged from the front-fanged
Australasia
Australasia is a region that comprises Australia, New Zealand and some neighbouring islands in the Pacific Ocean. The term is used in a number of different contexts, including geopolitically, physiogeographically, philologically, and ecologica ...
n
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 ...
snakes (
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 Emydoceph ...
) about 10 million years ago. The yellow-bellied sea snake is a part of the rapidly radiating
Hydrophis
''Hydrophis'' is a genus of sea snakes, venomous snakes in the subfamily Hydrophiinae of the family Elapidae. Species in the genus ''Hydrophis'' are typically found in Indo-Australian and Southeast Asian waters. Currently, around 36 species are ...
group.
Description
![pelamis platuras](https://upload.wikimedia.org/wikipedia/commons/0/00/Pelamis_platuras.jpg)
The yellow-bellied sea snake, as the name implies, has a distinctive bicolor pattern with a yellow underbelly and brown back, making it easily distinguishable from other sea snake
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 ...
. Yellow-bellied sea snakes, like many other species of sea snake, are fully adapted to living their whole lives at sea: mating, eating and giving birth to live young (
ovoviviparous
Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop insi ...
). Adaptations to aquatic life include the reduced
ventral
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...
scale size, laterally compressed body and paddle-tail for swimming,
valved nostrils and
palatine
A palatine or palatinus (in Latin; plural ''palatini''; cf. derivative spellings below) is a high-level official attached to imperial or royal courts in Europe since Roman times. seal for excluding seawater, and
cutaneous gas exchange Cutaneous respiration, or cutaneous gas exchange (sometimes called, skin breathing), is a form of Respiration (physiology), respiration in which gas exchange occurs across the skin or outer integument of an organism rather than gills or lungs. Cutan ...
for prolonging dive times.
This
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 ...
can uptake up to 33% of its
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
requirements through the
skin
Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation.
Other cuticle, animal coverings, such as the arthropod exoskeleton, have diffe ...
while diving and swimming at the surface of the water. Sea snakes also have a special salt
gland
In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland).
Structure
De ...
located in the lower jaw that was formerly believed to filter out salt from the surrounding seawater but has been found not to be used for that purpose, as sea snakes drink fresh water only.
:''See
snake scales
Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes . Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more joints ...
for terminology used here''
Morphology
The body of this snake is compressed, with the posterior less than half the diameter of the neck; the body scales are juxtaposed, subquadrangular in shape, and in 23–47 rows around the thickest part of the body; ventral scales, 264–406 in number, are very small and, if distinct, divided by a latitudinal
groove, but usually are indistinguishable from adjacent body scales. The head is narrow, with an elongated snout; head shields are entire, nostrils are superior, and nasal shields are in contact with one another; the prefrontal scale is in contact with second upper labial; one or two preoculars, two or three postoculars, and two or three small anterior temporals are present; seven or eight upper labials are found, with four or five below the eye, but separated from the border by a subocular. Colors of the snake are variable, but most often distinctly bicolored, black above, yellow or brown below, with the dorsal and ventral colors sharply demarcated from one another; ventrally, there may be a series of black spots or bars on the yellow or brown background, or the yellow may extend dorsally so there is only a narrow middorsal black stripe, or a series of black crossbars. Total length for males is up to , for females up to ; tail length for males is up to , females up to .
Distribution and habitat
The yellow-bellied sea snake is one of the most widely distributed snakes in the world.
It is completely
pelagic
The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...
and is often observed on oceanic
drift lines, using surface currents and storms to move around the ocean.
Their distribution appears to be largely determined by favourable water temperatures,
oceanic currents and recent formation of
land bridge
In biogeography, a land bridge is an isthmus or wider land connection between otherwise separate areas, over which animals and plants are able to cross and Colonisation (biology), colonize new lands. A land bridge can be created by marine regre ...
s that have blocked farther dispersal.
The yellow-bellied sea snake has an extensive distribution covering the entire tropical
Indo-Pacific
The Indo-Pacific is a vast biogeographic region of Earth.
In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...
, as well as extending to
Costa Rica
Costa Rica (, ; ; literally "Rich Coast"), officially the Republic of Costa Rica ( es, República de Costa Rica), is a country in the Central American region of North America, bordered by Nicaragua to the north, the Caribbean Sea to the no ...
, southern
California
California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...
, and northern
Peru
, image_flag = Flag of Peru.svg
, image_coat = Escudo nacional del Perú.svg
, other_symbol = Great Seal of the State
, other_symbol_type = Seal (emblem), National seal
, national_motto = "Fi ...
. It is the only sea snake to have reached the
Hawaiian Islands
The Hawaiian Islands ( haw, Nā Mokupuni o Hawai‘i) are an archipelago of eight major islands, several atolls, and numerous smaller islets in the North Pacific Ocean, extending some from the island of Hawaii in the south to northernmost Kur ...
. The favoured habitat for hunting and reproduction includes free floating mats of sea kelp occurring in the Indian Ocean. The species is the most commonly beached sea snake on the coast of
Southwest Australia
Southwest Australia is a biogeographic region in Western Australia. It includes the Mediterranean-climate area of southwestern Australia, which is home to a diverse and distinctive flora and fauna.
The region is also known as the Southwest Aus ...
, including records at beaches near metropolitan areas.
It is also reported from Christmas Island and Cocos (Keeling) Islands (Australia).
The sea snake has also been reported in colder waters such as the coasts of southern California,
Tasmania
)
, nickname =
, image_map = Tasmania in Australia.svg
, map_caption = Location of Tasmania in AustraliaCoordinates:
, subdivision_type = Country
, subdi ...
, and
New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
,
a country that would otherwise be free of snakes were it not for the infrequent visits of yellow-bellied sea snake and
banded sea kraits.
Though rare, the yellow-bellied sea snake is the most commonly seen sea snake in New Zealand waters, to the degree that the species can be considered indigenous to New Zealand and protected under the
Wildlife Act 1953
Wildlife Act 1953 is an Act of Parliament in New Zealand. Under the act, the majority of native New Zealand vertebrate species are protected by law, and may not be hunted, killed, eaten or possessed. Violations may be punished with fines of up to ...
.
These cold water occurrences are believed to be linked with
el Niño
El Niño (; ; ) is the warm phase of the El Niño–Southern Oscillation (ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific (approximately between the International Date L ...
events or severe storms.
They require a minimum of 16–18 °C (60.8 to 64.4 °F) to survive long term. In October 2015, they were reported and photographed on beaches in
Ventura County, California
Ventura County () is a county in the southern part of the U.S. state of California. As of the 2020 census, the population was 843,843. The largest city is Oxnard, and the county seat is the city of Ventura.
Ventura County comprises the Oxn ...
, well outside their normal range, for the first time in 30 years.
The yellow-bellied sea snake is the only sea snake to have been found in the Atlantic Ocean, although only in limited circumstances. The yellow-bellied sea snake's occurrence into the Atlantic is not considered a part of its native range, but rather a dispersal from its native Pacific range.
The yellow-bellied sea snake has been found in all the countries of Africa's eastern coast and all eastern islands, like Djibouti, Eritrea, Kenya, Madagascar, Mauritius, Mayotte, Mozambique, Réunion, Seychelles, Somalia, South Africa and Tanzania.
On the African Atlantic coast they have been reported to occur in the
Agulhas Current
The Agulhas Current () is the western boundary current of the southwest Indian Ocean. It flows south along the east coast of Africa from 27°S to 40°S. It is narrow, swift and strong. It is suggested that it is the largest western boundary curren ...
, with specimens found along the coasts of
South Africa
South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...
and
Namibia
Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and ea ...
.
The yellow-bellied sea snake has also been found in the Colombian Caribbean four separate times, making it the only sea snake to be found in the Caribbean Sea. However these occurrences are believed to be the result of human activity, be it ship discharge, intentional release or via the Panama Canal, as it is not considered a part of their native range. This is due to the
land bridge
In biogeography, a land bridge is an isthmus or wider land connection between otherwise separate areas, over which animals and plants are able to cross and Colonisation (biology), colonize new lands. A land bridge can be created by marine regre ...
between North and South America (
Isthmus of Panama
The Isthmus of Panama ( es, Istmo de Panamá), also historically known as the Isthmus of Darien (), is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It contains the country ...
), which formed from about 10 million years ago to 3 million years ago (i.e.,
continental drift
Continental drift is the hypothesis that the Earth's continents have moved over geologic time relative to each other, thus appearing to have "drifted" across the ocean bed. The idea of continental drift has been subsumed into the science of pla ...
), acting as a
dispersal barrier and preventing entry into the Caribbean Sea from the Pacific Ocean. The man-made
Panama Canal
The Panama Canal ( es, Canal de Panamá, link=no) is an artificial waterway in Panama that connects the Atlantic Ocean with the Pacific Ocean and divides North and South America. The canal cuts across the Isthmus of Panama and is a conduit ...
has not made a crossing of the isthmus possible presumably because it is
fresh water
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...
.
Due to the wide distribution of the species and relative lack of
dispersal barriers, it has been assumed that individuals from different localities represent a single breeding
population
Population typically refers to the number of people in a single area, whether it be a city or town, region, country, continent, or the world. Governments typically quantify the size of the resident population within their jurisdiction using a ...
(i.e., high
gene flow
In population genetics, gene flow (also known as gene migration or geneflow and allele flow) is the transfer of genetic material from one population to another. If the rate of gene flow is high enough, then two populations will have equivalent a ...
). However, a study that used
haplotype
A haplotype ( haploid genotype) is a group of alleles in an organism that are inherited together from a single parent.
Many organisms contain genetic material ( DNA) which is inherited from two parents. Normally these organisms have their DNA or ...
networks in two populations from
Costa Rica
Costa Rica (, ; ; literally "Rich Coast"), officially the Republic of Costa Rica ( es, República de Costa Rica), is a country in the Central American region of North America, bordered by Nicaragua to the north, the Caribbean Sea to the no ...
suggests that shallow genetic population structure exists, which reflects variation in colour patterns (brown and yellow in
Golfo de Papagayo and completely yellow in
Golfo Dulce).
Behaviour
Contrary to past beliefs, sea snakes require fresh water to survive and the yellow-bellied sea snake drinks precipitation that forms on the surface of sea water. This species has been reported to survive severe dehydration of up to 7 months during seasonal drought.
Yellow-bellied sea snakes breed in warm waters; they are
ovoviviparous
Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop insi ...
with a gestation period around 6 months. According to
Ditmars, females bear live young in tidal pools. They move poorly on land due to their smaller belly scales that form a
ventral
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...
keel
The keel is the bottom-most longitudinal structural element on a vessel. On some sailboats, it may have a hydrodynamic and counterbalancing purpose, as well. As the laying down of the keel is the initial step in the construction of a ship, in Br ...
.
They are sometimes observed in large aggregations of thousands on the surface of the water in oceanic
drift lines, which has been proposed as a strategy to catch prey. They hunt by floating on the surface of the water to attract
pelagic
The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...
fish that are seeking shelter; prey are captured via a backwards swimming motion and rapid lunge of the jaws.
The ability to swim backwards is an unusual and distinguishing characteristic of this species.
Heatwole proposed that these snakes find their prey by sensing the vibration generated by fish movement.
Venom
The venom of this species is highly potent, like that of other
sea snakes
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, where ...
. The subcutaneous of the venom is 0.067 mg/kg and the venom yield per bite is 1.0–4.0 mg. Yellow-bellied sea snake venom contains several different neurotoxins and two other isotoxins.
Antivenom
Sea snake venom can cause damage to skeletal muscle with consequent
myoglobinuria
Myoglobinuria is the presence of myoglobin in the urine, which usually results from rhabdomyolysis or muscle injury. Myoglobin is present in muscle cells as a reserve of oxygen.
Signs and symptoms
Signs and symptoms of myoglobinuria are usual ...
, neuromuscular
paralysis
Paralysis (also known as plegia) is a loss of motor function in one or more muscles. Paralysis can also be accompanied by a loss of feeling (sensory loss) in the affected area if there is sensory damage. In the United States, roughly 1 in 50 ...
or direct
renal
The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...
damage. The venoms of significant species of sea snake are neutralised with Commonwealth Serum Laboratories Ltd (of Melbourne, Australia) sea snake (''
Enhydrina schistosa
''Enhydrina schistosa'', commonly known as the beaked sea snake, hook-nosed sea snake, common sea snake, or the Valakadeyan sea snake, is a highly venomous species of sea snake common throughout the tropical Indo-Pacific. This species is implic ...
'') antivenom.
If that preparation is not available,
tiger snake or polyvalent antivenom should be used. No deaths have been recorded from bites in Australian waters. The ''E. schistosa'' antivenom was tested specifically on ''Pelamus platurus'', and it effectively neutralised the venom.
[http://www.ajtmh.org/cgi/content/abstract/23/1/135 Published 1973. Accessed May 2008.]
Cited references
Other sources
*
Ditmars, R.L. 1936. ''The Reptiles of North America''. Doubleday, Doran & Co. New York. 476 pp.
*
* Kropach, C. 1975 The yellow-bellied sea snake, ''Pelamis'', in the eastern Pacific. pp. 185–213 in: Dunson, W., ed., The Biology of Sea Snakes. Univ. Park Press, Baltimore, xi + 530 pp.
*
Smith, M.A. 1943. ''The Fauna of British India, Ceylon and Burma, including the Whole of the Indo-Chinese Sub-region. Reptiles and Amphibians. Vol. III. – Serpentes''. Taylor & Francis. London. 583 pp.
External links
Pelagic Sea Snakes and the animals that live on them Life is Short but Snakes are Long
{{Taxonbar, from=Q1247379
Reptiles described in 1766
Taxa named by Carl Linnaeus
Hydrophis
Reptiles of Pakistan
Reptiles of New Zealand
Reptiles of Western Australia
Reptiles of Japan
Reptiles of Mexico
Reptiles of Iran
Reptiles of Guatemala
Reptiles of Hawaii
Snakes of Australia