Distribution and Identification of Poisonous Sea Snakes 



tween a count made on the nefk and one made at tlie 

 middle of the body. 



Color Kolden yellow to yellowish Kreen shading to 

 pinkish white below ; body encircled by l)lack rings that 

 are widest along the vertebral midline and narrow on 

 the flanks, always much narrower than the interspaces 

 separating them : head uniformly yellow in the adult, 

 dark with a yellow horseshoe shaped mark on the crown 

 in the young. 



This is apparently the longest of the sea snakes, al- 

 though AipymirKs and A.itnilia exceed it in bulk. Adult 

 yellow sea .snakes frequently reach a length of r>i,4 to 

 6 feet, and a record length of 9 feet is reported, 



liemarhx: Ver.v little information is on record con- 

 cerning the habits and biology of this sea snake. It 

 seems to frequent deep water and often basks at the 

 surface. 



Venom yields from this snake are s\iri)risingly small 

 (.3 to 10 mg. I and toxicity lower than for mo.st sea 

 snake venoms, nevertheless several fatalities are on 

 record frnm the bite of this species, 



Annulated Sea Snake, ffi/t/ropliis ci/anocinchts 

 Daiulin. 



Idciiti/irdliiJii: Head smaller, neck longer and more 

 slender and bod.v more comi)ressed than in the yellow 

 sea snake. Head scales similar to those of the yellow 

 .sea snake except that there are usually 2 anterior tem- 

 porals. Kody scales with central keel or row of tuber- 

 cles. Incre.'ise of more than H (ustially 10 to 10) scale 

 rows between cnunt at ncik and <'oiint at midbody. 



Venom yields reported from this snake are aiiproxi- 

 mately double those rejiorted for the yellow sea snake, 

 and the toxicity is somewhat higher. Data from Malaya 

 indicate If. ri/iintii-iiii-tiis lauses more deaths than any 

 sea snake si)ecies except the beaked sea snake. 



Reef Sea Snake, Hydrophix onuifuH (Gray). 



Identification: A large headed, stout bodied sea 

 snake; body scales small. juxtai>osed. with a central 

 tubercle that is more strongl.v developed in the male: 

 increase of 12 to 20 scale rows between coinil at neck 

 and count at midboily. The combination of regular 

 head shields with nasals in contact with each other and 

 small, undivided ventrals of alnio.st uniform size the 

 entire length of the body will usually differentiate this 

 species from other sea snakes of similar body build. 



FioiiRF, IIG. — Head Scales of Uydrophis cyanocinctus. 



(See ;ilso iibile VI, tig. 4.1 Redr;iwii froiii Maki. i;«l. 



Color (lirly white. |)ale greenish, yellow or olive with 

 blackish crossbands that may or may not encircle 

 the body, are widest along the vertebral midline and are 

 as wide as, or \\ ider than, the interspace.s between them. 

 Head in adult olive, reddish, or dull yellow ; in young 

 blackish with the yellow horseshoe mark seen in some 

 other species. 



The adult length averages -1^2 to T>^{- feet with record 

 specimens of about 6Vj feet. 



UrnidrkK: This snake frequents mangrove swamps 

 but has been collected 12 to 20 miles offshore during 

 winter. Although it has not been seen to leave the 

 water voluntarily, it crawls fairly well and can lift its 

 head well free of the ground. It often bites if re- 

 strained. 



Figure 117. — Head Scales of Ilydrophis ornaius. Note 

 regular head scutes and contact of nasals. Redrawn 

 from Maki, 1931. 



The typical form is pale greenish white, olive or yel- 

 low with wide dark crossbands or rhond>oid spots. The 

 head is olive. The Philippine subspecies is uniformly 

 grayish green above and whitish below. A subs])ecies 

 with spotted or ocellate markings on the sides occurs in 

 Australian waters. 



Average length is 2.S to 3."> inches: maximum abimt 

 4."i inches. 



I'rnnirks: This sea snake lias a very wide range 

 extending from the Persian (Julf t<i the central Pacific 

 and from the Yellow Sea to Australia. It is plentiful 

 in some localities, e.g. Manila Ha.v. but very rare and 

 apparently onl.v a straggler in many others. It evi- 

 dently frequents shallow water, feu- dozens have been 

 taken in one haul of a bea<h seine. At least one fatality 

 is ascribed to its bite. 



Banded Small-headed Sea Snake, Ilydrophin fas- 

 rldfiis (Sc-liiioider). 



Identification: Certain species of the genus Hydro- 

 phis and the two species of Mirroreplialophis are re- 

 markable for their tiny heads and long slender necks. 

 This peculiar body form is most evident in the adult ; 



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