Astrotia stokesii
Encyclopedia
Commonly known as Stokes' seasnake, Astrotia stokesii is a large species of sea snake found in tropical Indo-Pacific oceanic waters.
. Its mid-ventral scales
are enlarged to form a distinct keel
on its belly, the keel frequently broken up into two wart-like tubercle
s. A. stokesii is highly variable in colour, ranging from cream to brown to black, often with broad black dorsal cross bands, or black rings.
Rostral as deep as broad; nasals shorter than the frontal, more than twice as long as the suture between the prefrontals; frontal longer than broad, as long as or slightly longer than its distance from the rostral scale; one pre- and two postoculars, 9 or 10 upper labials, fourth, fifth, and sixth catering the eye, if not divided to form a series of suboculars ; two or three superposed anterior temporals; no chin-shields. 39 to 47 scales round the neck, 48 to 53 round the middle of the body. Ventral scales
usually distinct only quite anteriorly, further back in pairs and not larger than the adjoining scales; scales much imbricate, pointed.
Total length 5 feet.
and Sri Lanka
to the South China Sea
and Strait of Taiwan. It also lives in all waters of tropical Australia.
bite, there are no reported human fatalities attributed to Stokes' seasnake.
These snakes sometimes form migrating groups in the thousands, drifting in meter-long slicks in the Strait of Malacca
. They are ovoviviparous
, producing small broods of five young each mating season.
in an appendix to Volume 1 of John Lort Stokes
' 1846 Discoveries in Australia
. It is currently the only member in the monotypic Astrotia genus. In 1972, McDowell resurrected the genus Disteira
and merged Astrotia into it, although Stokesii lacks the Oxyuranus pattern of venom gland muscle which typifies Disteira, and differs from others in that genus by number of body vertebrae and heart position. Cogger later refused to recognize the placement of Stokesii into Disteira.
Description
Stokes' seasnake is one of the heaviest and stoutest seasnakes, with the longest fangs of any marine snake. Its fangs are long enough to pierce a wetsuitWetsuit
A wetsuit is a garment, usually made of foamed neoprene, which is worn by surfers, divers, windsurfers, canoeists, and others engaged in water sports, providing thermal insulation, abrasion resistance and buoyancy. The insulation properties depend on bubbles of gas enclosed within the material,...
. Its mid-ventral scales
Ventral scales
In snakes, the ventral scales 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 contacts the paraventral row of dorsal scales on either side...
are enlarged to form a distinct keel
Keel
In boats and ships, keel can refer to either of two parts: a structural element, or a hydrodynamic element. These parts overlap. As the laying down of the keel is the initial step in construction of a ship, in British and American shipbuilding traditions the construction is dated from this event...
on its belly, the keel frequently broken up into two wart-like tubercle
Tubercle
A tubercle is generally a wart-like projection, but it has slightly different meaning depending on which family of plants or animals it is used to refer to....
s. A. stokesii is highly variable in colour, ranging from cream to brown to black, often with broad black dorsal cross bands, or black rings.
Rostral as deep as broad; nasals shorter than the frontal, more than twice as long as the suture between the prefrontals; frontal longer than broad, as long as or slightly longer than its distance from the rostral scale; one pre- and two postoculars, 9 or 10 upper labials, fourth, fifth, and sixth catering the eye, if not divided to form a series of suboculars ; two or three superposed anterior temporals; no chin-shields. 39 to 47 scales round the neck, 48 to 53 round the middle of the body. Ventral scales
Ventral scales
In snakes, the ventral scales 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 contacts the paraventral row of dorsal scales on either side...
usually distinct only quite anteriorly, further back in pairs and not larger than the adjoining scales; scales much imbricate, pointed.
Total length 5 feet.
Distribution
A. stokesii is distributed from PakistanPakistan
Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...
and Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
to the South China Sea
South China Sea
The South China Sea is a marginal sea that is part of the Pacific Ocean, encompassing an area from the Singapore and Malacca Straits to the Strait of Taiwan of around...
and Strait of Taiwan. It also lives in all waters of tropical Australia.
Habits
Although aggressive with a venomousVenom
Venom is the general term referring to any variety of toxins used by certain types of animals that inject it into their victims by the means of a bite or a sting...
bite, there are no reported human fatalities attributed to Stokes' seasnake.
These snakes sometimes form migrating groups in the thousands, drifting in meter-long slicks in the Strait of Malacca
Strait of Malacca
The Strait of Malacca is a narrow, stretch of water between the Malay Peninsula and the Indonesian island of Sumatra. It is named after the Malacca Sultanate that ruled over the archipelago between 1414 to 1511.-Extent:...
. They are ovoviviparous
Ovoviviparity
Ovoviviparity, ovovivipary, or ovivipary, is a mode of reproduction in animals in which embryos develop inside eggs that are retained within the mother's body until they are ready to hatch...
, producing small broods of five young each mating season.
Taxonomy
It was first published as Hydrus Stokesii by John Edward GrayJohn Edward Gray
John Edward Gray, FRS was a British zoologist. He was the elder brother of George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray ....
in an appendix to Volume 1 of John Lort Stokes
John Lort Stokes
Admiral John Lort Stokes, RN was an officer in the Royal Navy who travelled on HMS Beagle for close to eighteen years.Stokes grew up in Scotchwell near Haverfordwest, Pembrokeshire. He joined the Navy on 20 September 1824...
' 1846 Discoveries in Australia
Discoveries in Australia
Discoveries in Australia; with an account of the coasts and rivers explored and surveyed during the voyage of H.M.S. Beagle, in the years 1837-38-39-40-41-42-43, by command of the Lords Commissioners of the Admiralty...
. It is currently the only member in the monotypic Astrotia genus. In 1972, McDowell resurrected the genus Disteira
Disteira
Disteira is a genus of sea snakes.-History:Disteira was characterized by Boulenger in 1890 as having grooved maxillary teeth following the first pair of poison fangs...
and merged Astrotia into it, although Stokesii lacks the Oxyuranus pattern of venom gland muscle which typifies Disteira, and differs from others in that genus by number of body vertebrae and heart position. Cogger later refused to recognize the placement of Stokesii into Disteira.