ATRACTASPIS - MINI REVIEW 



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Fig. 3 Hatching of Atractaspis engaddensis. 



Fig. 4 Defense mimicry posture by Atractaspis engaddensis, with hidden 

 head and exposed tail. 



Fig. 5 Tail poking by Atractaspis engaddensis. 



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the coil so as to mimic the head (Fig. 4). The tail ends in a sharp tip 

 that the otherwise immobile snake uses for poking when grasped at 

 the posterior end of the body (Fig. 5). This behaviour may be 

 mistaken for a genuine strike with the fang and deter any potential 

 predator. Should that not suffice, there is always the hidden head that 

 can be produced quickly from underneath the body coils and inflict 

 a real, painful and dangerous strike. 



VENOM APPARATUS 



The venom apparatus of Atractaspis has not been dealt with in great 

 detail beyond the general statement that the maxillary/fang unit is 

 similar to that of vipers. This similarity is, however, superficial as 

 the articulation between the prefrontal and maxilla in Atractaspis is 

 in the form of a ball and socket articulation, which is more restricted 

 in its movements, but apparently stronger (Pasqual. 1962). This 

 condition may be important for the peculiar striking of these snakes, 

 which is performed with one fang at a time while the mouth remains 

 almost entirely closed (Fig. 6). Striking in this manner may be 

 considered as a special adaptation for fossorial snakes that feed in 

 narrow burrows underground. 



The venom fangs are relatively long and canaliculate and possess 

 a blade-like ridge near the orifice of the fang (Kochva & Meier. 

 1986), which may increase the wound and cause additional tissue 

 damage during the strike, thus facilitating the spread of venom. 

 Analyses of films taken during a strike through plastic sheathings 

 show first the establishment of a firm contact of the head with the 

 substrate, followed by the erection of the fang and piercing of the 

 substrate by arching, lateral bending and downward rotation of the 

 head (Fig. 6). Ejection of the venom is performed while the fang 

 moves backward, further cutting through the surface (Golani & 

 Kochva, 1988). 



The venom glands have a distinctive structure with secretion 

 tubules arranged concentrically around the main lumen (Fig. 7). 

 Unlike the viperids and elapids, there are no differentiated mucous 

 accessory glands, but mucous cells are found in each of the secretion 

 tubules close to the central lumen (Kochva et al., 1967). As in the 

 other families of venomous snakes, there are species (the 

 microlepidota group. Underwood & Kochva, 1993) with elongated 

 venom glands that reach far beyond the corner of the mouth (Kochva, 

 1959). The compressor muscle accompanies the gland along its 

 entire length and probably squeezes it during the strike so as to 

 increase the pressure in the central lumen and push the venom 

 through the venom duct, fang canal and into the wound. The species 

 with short glands (the bibrotti group) have a short, but thicker 

 compressor. 



In a 756 mm long A. engaddensis the right gland reached the 30"' 

 ventral and was 70 mm long, while in A. microlepidota it may reach 

 one third of the body length - more than 300 mm in a specimen of 

 900 mm (Scortecci, 1939). The left gland is usually longer than the 

 right gland in both species and it is sometimes twisted along its 

 longitudinal axis (Fig. 8). 



VENOM 



The venom of Atractaspis remained unknown for a long time, 

 probably because not many serious bites were reported until now 

 and it was thus ignored by toxinologists. In addition, the venom is 

 very difficult to obtain not only because of the relative paucity of 

 specimens collected, but also because of the difficulty in extracting 



