Hydrophis
belcheri, commonly known as
the faint-banded
sea snake or Belcher's sea snake, is a venomous species of elapid sea
snake. It has a timid
temperament and would normally have to be subjected to severe mistreatment
before biting. Usually those bitten are fishermen handling nets, although only
a quarter of those bitten are envenomated since the snake rarely injects much
of its venom. Because of this, and its docile nature, it is generally not
regarded as very dangerous. Although not much is known about the venom of this
species, its LD50 toxicity
in mice has been determined to be 0.24 mg/kg when delivered intramuscularly.
You may be somewhat
familiar with these sea snakes. They are quite common, and you may have seen
them in films or even in person. They are recognizable from their stripes.
Usually these snakes have no interest in confrontation, but if one feels
threatened, it may bite you. Three out of four times this will be no big deal,
since only about one quarter of Belcher’s Sea Snakes carry venom. Those that do
though have the highest concentration of venom in existence. Just a few
milligrams has the capacity to kill thousands of human beings, making this the
most poisonous snake in the world. Nonetheless, most Belcher’s Sea Snakes are
quite harmless thanks to a docile personality and a lack of venom.
Belcher's sea snake, which many times is
mistakenly called the hook-nosed sea snake (Enhydrina schistosa), has been erroneously popularized as
the most venomous snake in the world, due to Ernst and Zug's published book
"Snakes in Question: The Smithsonian Answer Book" from 1996.
Associate Professor Bryan Grieg Fry, a prominent venom expert, has clarified
the error: "The hook nosed myth was due to a fundamental error in a book
called 'Snakes in question'. In there, all the toxicity testing results were
lumped in together, regardless of the mode of testing (e.g. subcutaneous vs.
intramuscular vs intravenous vs intraperitoneal). As the mode can influence the
relative number, venoms can only be compared within a mode. Otherwise, its
apples and rocks.". Studies on mice and human cardiac
cell culture shows that venom of the inland taipan,
drop by drop, is the most toxic among all snakes; land or sea. The most
venomous sea snake is actually Dubois' seasnake (Aipysurus duboisii ).
Description
The belcher's sea snake is of moderate size, ranging
from 0.5 to 1 meter (about 20-40 inches) in adult length. Its thin body is
usually chrome yellowish in colour with dark greenish crossbands. The dorsal
pattern does not extend onto the venter. The head is short and has bands of the
same colours. Its mouth is very small but suitable for aquatic life. Its body
when viewed out of water appears to have a faint yellow colour. Its scales are
different from most other snakes in that they overlap each other. Each dorsal
scale has a central tubercle. The body is strongly laterally compressed
posteriorly. The ventral scales are very narrow, only slightly wider than the
dorsal scales.
Behavior
Like other sea snakes, it has a paddle-like tail which
makes it an expert swimmer, and it rarely goes on land. It eats fish and
shellfish. It breathes air, and has valves over its nostrils that close
underwater. It can hold its breath for as long as 7 to 8 hours while hunting
and even sleeping, but then has to surface for a quick breath of air. It is
generally docile and not aggressive. It may deliver a provoked bite only after
repeated severe treatment. It usually bites fishermen handling nets, but only
25% of those bitten are envenomed.
Distribution
Indian
Ocean (Philippines: Visayan area, Panay; New
Guinea), Gulf of Thailand, Australia (North Territory?, Queensland?), Solomon Islands [McCoy
2000]. Especially around the Ashmore
Reef in the Timor
Sea off northwest
Australia. Also New Caledonia
Taxonomic history
This species was first described and named
by John Edward Gray in 1849.
Etymology
Hydrophis comes from Greek "hydro"
= water + "ophis" = serpent.
The specific name, belcheri,
commemorates the Nova Scotian, Royal
Navy Captain, later Admiral, Sir Edward Belcher KCB, RN
(1799-1877) who collected the holotype.
Common names
H. belcheri is also referred to as Belcher's
ocean snake. Belcher's sea snake has been mistakenly called the
"hook-nosed sea snake" (which is actually Enhydrina schistosa) and in one instance was called the
"blue-banded sea snake" (which is actually one common name for Hydrophis cyanocinctus
