Having no legs doesn’t make you a snake

With the arrival of good weather it becomes more probable that we go out to the forest to enjoy nature, and the possibilities of finding snakes and other reptiles sunbathing on a stone or running among the grass increase. Snakes are the best known legless squamates, even though there are many other species of lizards which have also lost their extremities during their evolution. In this entry I’ll explain some distinctive characteristics of the three species of legless lizards that we can find in the Iberian Peninsula, the slow worm and the Iberian worm lizards.

LIMBLESS LIZARDS

The loss of legs is an evolutionary phenomenon that has happened more than once in the Squamata order. In fact, currently there are at least nine different lineages of legless lizards (not counting snakes).  In most groups this happens as an adaptation to a subterranean lifestyle (these usually present a short, round tail) or to a life among grass and vegetation (which usually show a long, slender tail).

Scheltopusik or European legless lizard (Ophisaurus apodus) a limbless lizard of the Anguidae family, photo by Tim Vickers.

Even though technically snakes are also legless lizards, unlike other groups, some ophidian species may pose a potential threat to human beings. This is why it’s important to know how to tell a snake from a legless lizard. There are some characteristics which can help us to differentiate a snake from a non-venomous lizard:

• Snakes haven’t got movable eyelids, while the rest of lizards do have.
• Ophidians have no external ear, while in most lizards the auditory channel can be appreciated.
• Snakes present specialized ventral scales for locomotion, while most limbless lizards have to move with the aid of the irregularities of the substrate.
• Many legless lizards can shed their tail as a defense mechanism (caudal autotomy) while snakes can’t.

Picture of a western green mamba (Dendroaspis viridis), a typical ophidian, by Jon Sullivan.

In a previous entry we already explained the different snake species that can be found on the Iberian Peninsula. Below, I’ll present you the three different species of legless lizards that we can find when we go out to visit natural landscapes of our country.

SLOW WORM (Anguis fragilis)

The slow worm is a legless squamate within the anguid family (Anguidae), in which we find the Anguinae subfamily, in which many species have lost their limbs or have them extremely reduced in size. The slow worm’s scientific name, Anguis fragilis, means literally “fragile snake”, referring to its ability to shed its tail to escape predators.

Photo of a slow worm close to Nismes, by © Hans Hillewaert.

Description

The slow worm is a small lizard with no visible legs, which can grow to 40 centimetres in length. It presents shiny, smooth scales and a small head with a poorly differentiated neck. Unlike snakes, it has movable eyelids, a forked tong and a small tympanic aperture.

Juvenile individuals usually have a golden or silver brown colouration with their sides and belly of a black coloration. Females and juveniles are similarly colored, being ochre with a dark brown or black belly and a black dorsal band, even though their coloration varies a lot.

Female slow worm, photografied at Hertfordshire by Peter O'Connor.

Males are more uniformly colored, with its back and sides of brown or grey coloration, while some older individuals show dark brown spots on their sides which may become of a bluish coloration with age.

Male slow worm, with distinctive blue spots, by Maria Haanpää.

Habitat and distribution

It’s a widely distributed reptile throughout most Europe, all being found from the Iberian Peninsula, England and Scotland up to Iran and west Siberia, passing through Greece and Turkey.

Map showing the slow worm's distribution, by Osado.

In the Iberian Peninsula it is found mainly in the northern half, occupying most Galicia, Asturias, Basque Country and Castile and León and the north of Aragon and Catalonia. The slow worm is a common species that goes unnoticed thanks to its inconspicuous customs. We can find slow worms in a wide variety of open habitats, such as grasslands, scrublands and open forests.

Distribution of the slow worm in Spain, by Lameiro.

Unlike most reptiles, which look for sunny places to warm up, the slow worm has a strong preference for wet and shadowy places, with plenty of low growing vegetation. It usually shelters under stones, tree logs, plastic wastes or small mammal’s burrows.

A male slow worm on its habitat, on the Netherlands, by Viridiflavus.

Biology and ecology

In the Iberian Peninsula the slow worm is active from the end of February to November, when hibernation starts, during which groups of up to 100 individuals can be found. Mating lasts from middle March up to July, during which males can be found fighting. Their gestation period lasts about three months, they are ovoviviparous species (females produce eggs but babies hatch inside their mothers) and females give birth from 2 to 22 young.

Many different species of reptiles, birds and mammals prey upon this species. As other lizards, the slow worm can shed its tail as a defence mechanism, which continues moving while the rest of the animal flees. The tail starts to regenerate after a few weeks.

Picture of a slow worm after shedding its tail, by SuperMarker.

Slow worms feed on snails, earthworms, insect larvae and many other small invertebrates, because, unlike snakes, they can’t unhinge their jaws to swallow big prey. This animal has been unfairly persecuted even though it is a helpful species for fields and gardens, as it feeds on many species considered pests for many cultivated plants.

Photo of a slow worm feeding on a slug, by Biosphoto/Thiebaud Gontard.

WORM LIZARDS (Blanus cinereus and Blanus mariae)

Amphisbaenians (clade Amphisbaenia) are a group of highly specialized subterranean squamates known as worm lizards. Even though externally they resemble some primitive snakes, they are different in that, while snakes first lost their front limbs and their left lung, worm lizards first lost their hind limbs and their right lung. Currently about 180 species of amphisbaenians are known, two of which are found on the Iberian Peninsula: the Iberian worm lizard (Blanus cinereus) and the Maria’s worm lizard (Blanus mariae), both differentiated by distribution and genomic studies.

Iberian worm lizard in Andalusia, photo by Antonio.

Description

Worm lizards are reptiles strictly adapted to a subterranean lifestyle, with bodies externally resembling that of earthworms. At first it’s difficult to tell the head and the tail apart, which is useful for worm lizards when it comes to escape predators (just as the slow worm, worm lizards can shed their tail, which doesn’t regenerate completely).

Iberian worm lizard next to Murcia. Note the similarity between head and tail. Photo by Jorozko.

Adults may measure more than 15 centimetres in length, with some individuals reaching 30 centimetres. The head is blunt and short, with a wide frontal scale to aid them while digging. Their eyes are vestigial (they can only detect changes of light intensity) and are covered by scales, while they have very acute hearing and smell.

Photo of the head of an Iberian worm lizard, where you can see the scale-covered eyes, by J. Gállego.

Scales are rectangular and are distributed evenly forming rings around their body. Coloration goes from pale pink, to dark purple and brown, and there is no sexual dimorphism between males and females. Like all amphisbaenians, worm lizards can move both forwards and backwards.

Adult worm lizard next to Cáceres, in which we can see the rectangular and evenly distributed scales. Photo by Mario Modesto.

Habitat and distribution

The two peninsular species of worm lizard are found exclusively in the Iberian Peninsula, except in the north and northeast, from sea level up to 1800 metres of altitude (in Sierra Nevada). The Iberian worm lizard (Blanus cinereus) is more widely distributed, while the Maria’s worm lizard (Blanus mariae) occupies the southwest of the peninsula.

Distribution map including both Blanus cinereus and Blanus mariae, by Carlosblh.

Worm lizards are found in a wide variety of habitats, from forests of holm oaks, pine trees and oaks to crops, gardens and sandy areas. They have subterranean habits, and usually take shelter under rocks and logs. Like the slow worm, worm lizards prefer humid zones and with soft soil, easy to dig into.

Biology and ecology

Worm lizards are active all year round, even though their activity specially intensifies during spring, summer and after rainy weather. During the day they usually shelter in underground galleries or under logs and rocks. In winter they maintain their body heat, moving through galleries at different depths or staying under sun warmed stones.

Photo of an Iberian worm lizard next to Cádiz, photo by Jorge López.

Their diet is composed of insects, arachnids and other arthropods found between leaves or underground. Worm lizards are eaten by a great number of terrestrial vertebrates, and their defense mechanisms include: tail scission, escaping to some of their galleries or curling up to form a ball.

Video of an Iberian worm lizard from Albacete, by Encarna Buendia.

The reproduction season goes from February to June, while mating usually occurs between April and May. Females lay a single relatively large egg, which is abandoned buried underground. Incubation period lasts for 69 to 82 days, and the newborn measure between 78 to 86 millimetres.

Photo of a pair of Iberian worm lizards in a garden near Seville, by Richard Avery.

OTHER LEGLESS LIZARDS

As I’ve already said, apart from the species described above, there are many other groups of limbless lizards over the world. Some of these other groups are:

Scincidae family: A family of chubby, short legged lizards, many of which have no functional limbs. In the Iberian Peninsula we can find two species: the Bedriaga’s skink (Chalcides bedriagai) and the western three-toed skink (Chalcides striatus).

Western three-toed skink, photo by Benny Trapp.

Pygopodidae family: A group of lizards with absent or reduced limbs, related to geckos.

Photo of a Burton's legless lizard (Lialis burtoni) from southern Australia, by Matt.

Dibamidae family: Legless tropical lizards of subterranean habits.

Photo of a dibamid called Anelytropsis papillosus, taken from Tod W. Reeder et al.

Anniellidae family: American legless lizards.

A legless lizard from the Anniella genus, form California, by Marlin Harms.

Even if most legless lizards are harmless, it doesn’t mean we can touch them and handle them in any form we want when we find them in nature. Legless lizards, as most wild animals, are easly stressed by human handling and shouldn’t be handled except for scientific purposes. The best way to enjoy nature is by observing it without disturbing it.

REFERENCES

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

• Cover photo: David López Bosch.
• http://animals.howstuffworks.com/snakes/legless-lizard-vs-snake1.htm
• http://www.mapoflife.org/topics/topic_378_Limblessness-in-lizards/
• http://www.vertebradosibericos.org/reptiles/listareptiles.html
• http://www.magrama.gob.es/es/biodiversidad/temas/inventarios-nacionales/0904712280003d45_tcm7-21472.pdf
• http://www.asturnatura.com/especie/anguis-fragilis.html
• http://www.vertebradosibericos.org/reptiles.html
• http://reptile-database.reptarium.cz/species?genus=Anguis&species=fragilis

Danger, poisonous mammals!

We usually associate snakes, spiders, jellyfish, etc. as venomous animals par excellence, but did you know that there are poisonous mammals? In this article we will discover who are they and the nature and use of their poisons.

THE PLATYPUS

The platypus (Ornithorhynchus anatinus) is the most famous among the poisonous mammals, and not just for this feature. With a peak like a duck and oviparous (laying eggs), when it was discovered some scientists thought it was a fraud.

Platypus (Ornithorhynchus anatinus). Photo by Jonathan Munro

They belong to the order monotremes, which means “one hole” in reference to the cloaca, the end of the digestive and reproductive systems. Some evolutionary biologists refer to them as the “missing link” between reptiles and mammals, as they have characteristics of both groups. Monotremes are the only mammals that lay eggs, but his body is covered with hair and the young are fed with breast milk. They are distributed by Australia, Tasmania and New Guinea.

Platypuses have a spur on the hind legs, which only in the case of males, release poison produced by femoral glands (located in the leg). The male uses it mainly to defend their territory and establish their dominance during the mating season, although if it is bothered also uses it as a defense. This poison can kill small animals, including dogs, and cause severe pain and swelling in humans. This pain can last days or months.

Spur on the hind leg of a platypus. Photo by E. Lonnon

Toxins are four proteins, three of which are unique to the platypus. They are like the defensins (DLP, defensin-like proteins). These are globular proteins, small and compacted, involved in the activation of pain receptors. Understanding how these toxins act it has special interest because they cause a lasting and severe pain; it may open new chances in the synthesis of analgesic drugs.

Short-beake echidna (Tachyglossus aculeatus). Photo de Tony Britt-Lewis

Echidnas (family Tachyglossidae) complete the order of monotremes with the platypus; consequently they are also oviparous. The family consists of four species, with the common characteristic of having the body covered with dense hair and spines. They are mainly insectivores specializing in ants and termites.

Like the platypus, they also have spurs behind the knees, but their secretions are not poisonous. The substances are used to mark their territory, according to the recent studies.

SLOW LORIS

As we saw in a previous post, lorises are primates in the prosimians suborder. They are nocturnal, arboreal and feed primarily on insects, vegetables and fruits. The slow lorises (Nycticebus) living in Southeast Asia, are the only poisonous primate. They possess poison glands on the elbows (brachial gland), and poison their body with arms and tongue, which can also join saliva and be transmitted by bitting.

Pygmy slow loris (Nycticebus pigmaeus). Photo by Ch’ien C. Lee

In this case the poison is used as a defense against predators, causing them pain, inflammation, necrosis (cell death) in the area of the bite, hematuria (blood in urine) or in some cases anaphylactic shock (allergic reaction) which can lead to death, even in humans (some are threatened by the illegal pet trade and traditional Chinese medicine). The poison also serves as protection for the young, they are licked by their parents and the poisonous secretion is distributed throughout the coat. Being poisonous, unusual among primates, can help counteract the disadvantages of its slow movements. Exudate from glands, as in echidnas, can also give olfactory information of range and territory between individuals of loris (Hagey et al., 2007).

Kayan loris (Nycticebus kayan). Photo by Ch’ien C. Lee

Toxins are polypeptides (generated when glandular secretion is mixed with saliva) and an unidentified steroid. Secretion is similar to the allergen Fel d 1 which is in the domestic cat and cause allergies in humans (Hagey et al., 2006; Krane et al., 2003).

It is believed that slow lorises even have converged evolutionarily with cobras, for his defensive behavior when threatened, whistling and raising his arms around his head. (Nekaris et. al, 2003).

Mimicry between loris and cobras. 1. Javan slow loris, 2 y 3. Spectacled cobra, 4. Bengal slow loris. Photo by Nekaris et. al.

In the following video a lazy lori is disturbed and hisses like a snake while trying to bite:

SOLENODON OR ALMIQUI

They are small and nocturnal mammals, basically insectivores, that live in the West Indies. The Hispaniolan solenodon (Solenodon paradoxus), also known as the Dominican solenodon, Haitian solenodon or agouta, lives on the island de La Española (Dominican Republic and Haiti) while The Cuban solenodon or almiqui (Solenodon cubanus) is distributed throughout Cuba. They are considered living fossils because they have similar characteristics to primitive mammals of the end of the Mesozoic Era (kingdom of the dinosaurs).

Hispaniolan solenodon (Solenodon paradoxus). Photo by Eladio M. Fernández.

Unlike other poisonous mammals, toxic saliva is produced under the jaw (submandibular glands), which is transported by pipes to the front of the mouth. The second incisor teeth have a groove where toxic saliva accumulates to promote their entry into the wounds. They are the only mammals that inject venom through its teeth, similar to the way snakes do.

Paradoxus Solenodon lower jaw incisor showing the groove. Photo by Phil Myers

The main function of this venom is to immobilize prey, as well as insects they can hunt small vertebrates such as reptiles, amphibians and birds.

Cuban solenodon (Solenodon cubanus). Photo by Julio Genaro.

This poison may have been developed to keep alive but immobilized prey during times of shortage, to aid in digestion, minimize energy expenditure in the struggle for hunting and face prey even twice as big as them. This venom is not deadly to humans.

SHREWS

The northern short-tailed shrew (Blarina brevicauda), the Eurasian water shrew (Neomys fodiens) and the Mediterranean water shrew (Neomys anomalus) also have submandibular glands similar to solenodons. They are distributed by North America (northern short-tailed shrew) and Europe and Asia (water shrews), including the Iberian Peninsula.

The northern short-tailed shrew (Blarina brevicauda). Photo by Gilles Gonthier.

The short-tailed shrew can consume up to three times its weight in food per day. Their saliva is the most poisonous and uses it to paralyze their prey, to eat them or keep them alive in times of shortage. The water shrews also store its immobilized prey under rocks.

Mediterranean water shrew (Neomys anomalus). Photo by Rollin Verlinde.

These animals attack from behind and bite the neck of its prey so that the poison acts more quickly, affecting the central nervous system (neurotoxins). The respiratory and vascular system is also affected and causes seizures, incoordination, paralysis and even death of small vertebrates.

Eurasian water shrew (Neomys fodiens). Photo by R. Altenkamp.

Its teeth don’t have grooves as the solenodons do, but a concave surface to store the toxic saliva.

Lower jaw of Neomys anomalus. Photo by António Pena.

It is suspected that other mammals also produce toxic saliva similarly, as the European mole (Talpa europaea) and other species of shrew, but there are no conclusive studies.

MANED RAT

The maned rat or crested rat (Lophiomys imhausi), lives in Africa and  uses his poisoned hair to protect themself from predators.

Maned rat (Lophiomys imhausi). Photo by Kevin Deacon

Unlike other mammals that produce their own poison, the crested rat gets toxin (called ouabain) from the bark and roots of a tree (Acokanthera schimperi). Chews the bark and the mixture of saliva and toxins are distributed on the body. Their hairs are cylindrical whith a perforated microscopic structure, which favors the absorption of venom. In case of danger, it bristles and shows his brown coat with white stripes, warning of its potential danger. This strategy of persuasion based on brightly colored warning is known as aposematism present in many animals, such as bees.

In this BBC video you can see a crested rat and a hair under the microscope absorbing ink, showing its porous structure:

It is unknown how it is immune to the toxin, since it is the same substance used by some African tribes for hunting such large animals like elephants.

Ouabain is a glycoside which controls the heartbeat, causing infarcts if absorbed in large quantities. The study of the mechanisms that protect the crested rat of a substance that regulates the heartbeat, can help develop treatments for heart problems.

European hedgehogs (Erinaceus europaeus) have similar behavior (smearing the body with foreign poison), but it is not established whether the objective is defensive because it does not scare away predators.

In conclusion, strategies, practices and nature of the poison in mammals are varied and their study may have important medical implications for drug development and increase awareness of the evolutionary relationships between different groups of living animals (reptiles-mammals) and their ancestors.

REFERENCIAS

• Platypus poison
• Scientists discover the function of the echidna’s spur
• Los primates venenosos existen
• El único primate venenoso del mundo ya no está solo
• “Venom” of the slow loris: sequence similarity
  of prosimian skin gland protein and Fel d 1 cat allergen
• Venomous Slow Loris May Have Evolved To Mimic Cobras
• La rata que se unta con veneno para defenderse
• ¿Es cierto que los erizos se embadurnan de veneno?
• Pequeños pero feroces: mamíferos venenosos
• Are slow lorises really venomous?
• Encuentro con un “fósil viviente” en R. Dominicana
• Imagen de portada de Dave Watts

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).

Viperine water snake (Natrix maura), aglyphous

Montpellier snake (Malpolon monspessulanus), opisthoglyphous

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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:

• Cover photo: Aecuvis.
• http://www.trebago.com/revistas/01/08serpientes.asp
• http://anfibiosyreptileslarioja.blogspot.com.es/
• http://www.moroccoherps.com/Inicio/
• http://www.faunaiberica.org/?page=categoria&tipo=ofidios
• http://www.vertebradosibericos.org/reptiles/listareptiles.html
• http://manual-ofidico.blogspot.com.es/2012/08/diferencias-entre-serpientes-venenosas.html

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