Vipera_aspis_Lothringen_0442

Iberian ophidians: nice snakes and venomous vipers

In my first blog entry I talked about the different kinds of snake that exist based on their dentition. In this entry, I’ll explain what species of ophidian we can find in the Iberian Peninsula, which species are venomous and which aren’t, and how we can identify the different species we can find when we are on the field. As we will see in this entry, snakes have been unfairly demonized, as the species in the Iberian Peninsula pose no threat to us.

INTRODUCTION

In the Iberian Peninsula we can find 13 different species of snakes, with representatives of three of the four types of dentition I talked about in my last post. There aren’t any proteroglyphous snake because the members of the Elapidae family are restricted to tropical and subtropical habitats. Most of the iberian species are snakes of the Colubridae family (aglyphous or opisthoglyphous) or vipers and adders of the Viperidae family (solenoglyphous).

Natrix maura bo
Viperine water snake (Natrix maura), aglyphous
Malpolon bo
Montpellier snake (Malpolon monspessulanus), opisthoglyphous
Vipera latastei bo
Snub-nosed viper (Vipera latastei), solenoglyphous

COLUBRIDS vs. VIPERS

When we find a snake in the wild it’s important to know if that animal is a colubrid or a viper. Bites from Iberian colubrids are mostly harmless because they have either an unspecialized non-venomous dentition (aglyphous) or posterior venomous fangs (opisthoglyphous) which usually doesn’t inject venom and even if they do, normally they don’t inject enough venom for it to be dangerous. On the other hand, as Iberian vipers are solenoglyphous, they inject large quantities of venom, being vipers responsible for most of the snake bite accidents in Spain. Yet, bites are extremely rare, and most happen after a too prolonged manipulation of the animal.

To identify a snake as a colubrid or a viper there are some anatomical characteristics which tell them apart. These characteristics are usually only applicable to iberian ophidians; species from outside the Iberian Peninsula may present different combinations of characters.

The most cited character is the pupil. Normally vipers show an elliptic, slit-like pupil, while colubrids present a round pupil. However, this character is variable, because with low-light conditions a viper’s pupil may look round as the eyes of these animals can adapt to darkness.

PUPILA
Colubrid with round pupil (ringed snake, Natrix natrix) and viperid with elliptic pupil (snub-nosed viper, Vipera latastei). Photos by Honorio Iglesias.

The second character refers to the shape of the body. While colubrids are mostly thin, have an undifferentiated neck and a long slim tail, vipers have a triangular-shaped head with a neck differentiated from the body, and a short and conic tail.

BODYYY
Aesculapian snake (Zamenis longissimus) and Baskian viper (Vipera seoanei, photo by Daniel Gómez)

Although it may be difficult to look at, scales can be useful to tell colubrids and vipers apart. Vipers always present keeled scales, which have a little keel-like protuberance longitudinally on it. On the other side, even though they can have some keeled scales, most colubrids present smooth scales.

SCALES
Smooth scales of a horseshoe whip snake (Hemorrhois hippocrepis, photo by Saúl Yubero) and keeled scales of an asp viper (Vipera aspis, photo by Grégoire Meier)

Finally, while colubrids are active animals and usually flee before we can get close to them, vipers rely on their camouflage to avoid predation. Therefore, they stay still so we can’t see them, and may bite if they feel cornered.

IBERIAN OPHIDIANS

Colubridae family:

Coronella genus: Known as smooth snakes. In the Iberian Peninsula we can find the northern smooth snake (Coronella austriaca) which presents a dark mask-like spot covering from the nasal openings up to the neck and dark irregular markings on its back, and the southern smooth snake (Coronella girondica) which presents a pair of parietal marks and dark transversal spots on its back.

Coronella aust gir
Northern smooth snake (Coronella austriaca, left, photo by Christian Fischer) and southern smooth snake (Coronella girondica, right, photo by Evaristo Corral)

Hierophis genus: The green whip snake or western whip snake (Hierophis viridiflavus) is a brightly-coloured snake with a pattern of black, yellow and green spots over its body. Even though they can grow up to 170 cm of length they are not venomous. It can be usually found from temperate forests to crop fields, and even in abandoned buildings.

Hierophis viri
Green whip snake (Hierophis viridiflavus), juvenile (left, by Polypterus) and adult (right)

Natrix genus: Commonly known as water snakes due to their affinity for aquatic habitats. In the Iberian Peninsula we can find two species, the viperine water snake (Natrix maura) named after its zigzag marking and its keeled scales similar to a viper, and the grass or iberian ringed snake (Natrix astreptophora) which presents reddish pupils, an extremely variable coloration and a black “ring” in juvenile individuals.

Natrix mau nat
Viperine water snake (Natrix maura, left, photo by Honorio Iglesias) and iberian ringed snake (Natrix astreptophora, right photo of Fafner).

Zamenis genus: The Aesculapian snake (Zamenis longissimus) is a slim, long and harmless colubrid with a characteristically narrow and elongated skull. It is normally found on forested areas, with different microclimatic variations to aid it on its thermoregulation. This species is the one represented coiled around the rod of Aesculapius and the Bowl of Hygieia, symbols of medicine and pharmacy respectively.

Zamensis long
Aesculapian snake (Zamenis longissimus) (left by Amiralles).

Hemorrhois genus: The horseshoe whip snake (Hemorrhois hippocrepis) is an aglyphous colubrid that, even if it may bite if touched or grabbed, it’s not considered a venomous species. It presents a transversal mark on its head from one eye to the other, and another mark in the shape of a horseshoe on its neck, which gives this species its common name. It’s a species typical of rocky habitats.

Hemorrhois hippo
Horseshoe whip snake (Hemorrhois hippocrepis). Photos by Accipiter and Raúl León.

Rhinechis genus: The ladder snake (Rhinechis scalaris) receives its common name due to the stripes that juvenile specimens present on their back, similar to a ladder, even though adult individuals may present only longitudinal stripes on their body without any transversal marks connecting them. Despite being an apparently aggressive snake, it rarely bites and is harmless to human beings.

Rhinechis sca
Ladder snake (Rhinechis scalaris). Photos by Matt Wilson (left) and by Fernando Fañanás (right).

Macroprotodon genus: This is one of the few venomous species in the Peninsula. The western false smooth snake (Macroprotodon brevis) is an animal common on many different Mediterranean habitats. Even if it’s venomous, its small opisthogyphous mouth and its calm behavior make it totally harmless. It is characterised by a dark mark on the back of its head, and its short and flattened skull.

Macroprotodon brev
Western false smooth snake (Macroprotodon brevis). Photos by Saúl Yubero and Amiralles, respectively.

Malpolon genus: With specimens growing up to two and a half meters of length, the Montpellier snake (Malpolon monspessulanus) is the largest ophidian of the peninsula. Due to its opisthoglyphous dentition it normally doesn’t inject venom when biting (which is extremely rare), but larger individuals with much wider mouths may inject venom, but to cause symptoms it should hold its bite for a long period of time (most bites, even if rare, are dry warning bites). It is easily recognisable for its prominent eyebrows which give it a ferocious look.

Malpolon mons
Montpellier snake (Malpolon monspessulanus). Photos by Herpetofauna and RuizAraFoto respectively.

RuizAraFoto

Viperidae family:

There’s only one genus of vipers on the Iberian Peninsula with three representative species. Vipers and adders usually have a wide and triangular head, a lightly elevated snout and usually present a zigzag pattern on their back which help them camouflage. The three Iberian species are venomous, but thanks to modern medicine, their ocasional bites aren’t harmful to human beings. The asp viper (Vipera aspis), the most venomous snake in the peninsula, presents grey, golden or yellow scales, with black or green spots. The snub-nosed viper (Vipera latastei) is the most common viper in the peninsula and its coloration varies from brown to grey. Finally the Baskian or Portuguese viper (Vipera seoanei) is a middle-sized viper and with a highly polymorphic pattern.

Vipera asp lat seo
Asp viper (Vipera aspis, top left, photo by Felix Reimann), snub-nosed viper (Vipera latastei, top right, photo by Honorio Iglesias) and Baskian viper (Vipera seoanei, bottom, photo by Andre Schmid).

As we have seen, snakes and vipers aren’t as bad as they are portrayed to be. Most species flee from human beings, and accidents and bites happen when we force them to interact with us too much. Also, ophidians help farmers and agriculturers by hunting and eating species traditionally seen as vermin. If we leave snakes and vipers alone, we will be able to enjoy the beauty of this animals in peace.

REFERENCES

The following sources have been consulted in the elaboration of this entry:

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