Poisonous Snakes of tho World 



imi<l> I'iclicr ill llic iuiiiiIhts of spccii-s, niid tlm 

 <list I'iliiil ii)i) (if soiiH- III' tlu'Sf is poorly kiiowii. 

 Ni<vcrtlu'U>ss, if tliis maiuiul is used c'i)i-n'rtl\ , miiiI 

 if flit'iv is an !itl(M|iiali- s|«'rinicii lo woik willi, 

 it siioiilil 1h> iiossililc (() (list iiifjiiisli tirsi Ix'twccii 

 |>(iisoMoiis aiiil iiiin|i<iis(iii(>us siuikes, tiicii, if poi 

 soiKHis, lo asccilaiii till' coiii'cl (jjciicric idciil itica- 

 lioii ill alioiit '.•0 percent of tiie cases, and liiuilly 

 to urri\(' at the coirect species in about .'5 out of 4 

 cases. 



P'irst, if tiiere is any doulit that I lie animal /■••■ a 

 siiiike and a poisonous one, oi- if I he family of the 

 snake is unknown, tlieii Key to the Families of 

 Snakes. pa<re -W lids chapter, shouKl he con- 

 sulted. If the snake is known to he a poisonous 

 land snake, then refer to the coriect geographic 

 section of Cluipter VII and thence to the descrip- 

 tions of the common species of the area; if a 

 poisonous marine snake, refei- to Chapter VIII. 



If i)ractical)le every medical unit that enters 

 an area where snakebite is a hazard should build 

 up an identified collection of local poisonous and 

 nonpoi.sonous snakes (see p. 32 for directions). 

 Small individuals or just the heads of large 

 snakes should be sufficient. Such collections are 

 often essential foi' i-apid identification of danger- 

 ous species. 



If the specimen cannot be identified readily, it 

 may be : 



1. An aberrant individual or one from an 

 atypical population; 



2. An uncommon species listed in the regional 

 table but not described in detail ; 



3. An unknown species or one not previously 

 known from that geograi)hic region; 



4. A harmless species incorrectly identified as 

 poisonous. (To confirm the family, recheck char- 



FiGURE 4. — Drawing of head of pit vijier. showing the 

 po.sition and appearance of the loreal pit. Tliis heat- 

 sensitive structure is characteristic of the famil.v 

 Crotalldae. 



acteristics using Key to the I-'amilies, this 

 ciiapter.) 



In examiiimg an iiiiiilenrilieil ^iiakc look first 

 at the head. In all pit \ipers (family ('rotali- 

 dae) tlier(( is a deep hollow between the eye. and 

 nostril and slightly below a line connecting the 

 two (.see figiiri^ 4). The impression is one of an 

 e.xti'a nosti-il. (A large pit \\\wv, Both ropx atrox, 

 is know II in .Mexico as fimlro tun'ices or four no.s- 

 trils.) 'I'hese pits are actually sensiti\e heat 

 receptors. They absolutely identify a snake as a 

 pit viper, since they are not seen in any other 

 type of snake. IIowe\er, some ])ythons and boas 

 do ha\(' pits on the upper lip. The ])its may be 

 ditlicnli to recognize for they are often camou- 

 flaged by the head mai'kings so that they are not 

 visible except by close inspection; this ofl'crs an- 

 other reason for bringing the intact snake in for 

 ident ilication. 



DISTINGUISHING FEATURES 

 IN IDENTIFICATION 



Venom Apparatus 



Fangs and venom glands are the only anatomic 

 features that set poisonous snakes apart from non- 

 poisonous ones. Caution is demanded in examin- 

 ing the mouth of a freshly killed snake ; the biting 

 reflex may persist in a severed head for as long 

 as 45 minutes. The long, moveable fangs of 

 vipers, normally sheathed in whitish membrane 

 and rotated parallel to the roof of the mouth, can 

 be readily demonstrated and recognized. Fangs 

 of elapid snakes (cobras, kraits, mambas, and 

 related species) are smaller in size, located 

 toward the front of the mouth, and fixed 

 to the jaw (see fig. 5). In cobras, mambas, 

 and some other species they are large enough to 

 be readily recognized, but in coral snakes and 

 some other small elapids this is not the case. En- 

 larged anterior teeth are seen also in some nonpoi- 

 sonous snakes and can be confusing. Sea snake 

 fangs are small and hard to distinguish. Rear 

 fangs in colnbrid snakes are rather difficult to see 

 and extremely difficult to diii'erentiate from non- 

 srooved enlarged teeth found at the back of 

 the jaw in many nonpoisonous snakes. Fortu- 

 nately only a few rear-fanged snakes in Africa 

 are sufficiently dangerous that their identification 



26 



