Vipera ammodytes

Species of snake

Vipera ammodytes, commonly known as horned viper, long nosed viper, nose horned viper, and sand viper, poskok is a species of viper found in southern Europe, mainly northern Italy, the Balkans, and parts of Asia Minor. Like all other vipers, it is venomous. It is reputed to be the most dangerous of the European vipers due to its large size, long fangs (up to 13 mm) and high venom toxicity. The specific name, ammodytes, is derived from the Greek words ammos, meaning "sand", and dutes, meaning "burrower" or "diver", despite its preference for rocky habitats. Five subspecies are currently recognized, including the nominate subspecies described here.

V. ammodytes grows to an average total length (snout tail) of , although individuals usually measure less than Maximum length also depends on locality, with northern forms distinctly larger than southern ones. In one field study on Golem Grad island (in Macedonia), for example, females averaged 35 cm., and males at 37 cm. ; the largest captured during the study was a male, at 66 cm. long. This indicates some degree of regional or insular dwarfism. The head is covered in small, irregular scales, that are either smooth or only weakly keeled; a pair of large supraocular scales also extends beyond the posterior margin of the eye. Ten to thirteen small scales surround each eye, and two rows separate the eye from the supralabials. The nasal scale is large, single (rarely divided), and separated from the rostral by a single nasorostral scale. The rostral scale is wider than it is long. The most distinctive characteristic is a single "horn" on the snout, just above the rostral scale. It consists of approximately nine to seventeen small scales, arranged in two (occasionally three or four) transverse rows. and sand natter. In Montenegro, Croatia, Bosnia and Herzegovina, Macedonia, and Serbia, a common name used for this snake is poskok (поскок), meaning 'hopper'.

North eastern Italy, Slovenia, Croatia, Bosnia Herzegovina, Serbia, Montenegro, Albania, Kosovo, Macedonia, Greece (including Cyclades), southern Austria, Romania, Bulgaria, Turkey, Georgia and Syria. The type locality is listed as "Oriente". Schwarz (1936) proposed that the type locality be restricted to "Zara" (Zadar, Croatia). V. ammodytes primarily inhabits dry, rocky hillsides with sparse vegetation. Not usually associated with woodlands, but if so it will be found there around the edges and in clearings. Sometimes found in areas of human habitation, such as railway embankments, farmland, and especially vineyards if rubble piles and stone walls are present. May be found above 2000 m at lower latitudes.

Adults generally feed on small mammals and birds, whilst juveniles predominantly eat lizards. Feeding behavior changes and is influenced heavily by prey size. Larger prey are struck, released, tracked, and swallowed, while smaller prey is swallowed without using the venom apparatus. Occasionally, other snakes are eaten.

Before mating, the males of this species will engage in a combat dance, similar to adders.

This is likely the most dangerous snake to be found in Europe. In some areas it is at least a significant medical risk. The venom can be quite toxic [based on tests conducted solely on mice], but varies over time and among different populations. Novak et al. (1973) give ranges of 0.44–0.82 mg/kg and IV and 0.19–0.64 mg/kg IP. Minton (1974) states 6.6 mg/kg SC. Humans respond rapidly to this venom, as do mice and birds. Lizards are less affected, while amphibians may even survive a bite. European snakes, such as Coronella and Natrix, are possibly immune.

This species has often been kept in captivity and bred successfully.