A SNAKE WITH A HEAD AT EACH END? - THE AMPHISBAENA AWAKES!

Amphisbaena portrayed in a mediaeval bestiary

As documented in a previous ShukerNature blog article (click here to read it), freak two-headed (aka bicephalic or dicephalous) snakes, although rare, are by no means unknown. In some examples, the two heads each emerge directly from the body; in certain others, they each possess their own neck that emerges independently from the body; and in a few instances, one head emerges directly from the body whereas the other emerges via a neck. However, what they all have in common is that both heads occur at the same end of the body, the front (anterior) end, with a tail at the posterior end.

This is why the freak specimen of rough earth snake Virginia striatula (a small, non-venomous, fossorial colubrid) discovered three weeks ago by workmen at the home of the Logan family in South Carolina (and cared for since then by the grandfather of the two Logan children, Preston and Savanna) is so very special – because this remarkable little snake's two heads are located at opposite ends of its body! Instead of possessing a tail, it sports a head at the posterior end of its body, plus a head at the anterior end as normal. This extraordinary teratological condition is known as amphicephaly, and, as will be seen a little later here, is so rare that the Logans' new pet may be the only modern-day example ever confirmed – always assuming, however, that it really is amphicephalous.

The Logan family's putative amphicephalous snake (© Foxcarolina.com)

On 24 September 2012, America's Fox News released a short video of the snake as part of an interview with the Logan family concerning it (click here to view it), and their report claims that the snake definitely has two heads, each with its own pair of eyes, a mouth, and a tongue, but that one head is more dominant than the other, though each head will take control of the body's movements. Having watched the video closely, I have been unable to spot a tongue emerging from the mouth of the subordinate head, in contrast to the constant tongue-flicking behaviour of the dominant head. However, the subordinate head does appear to possess a pair of eyes (or eye-like markings?). So, could the Logans' snake truly be amphicephalous, and, if so, are there any verified precedents? Or is there some other, more orthodox, conservative explanation?

A normal rough earth snake (Jscottkelley/Wikipedia)

Quite a number of snake species (especially fossorial ones) and also lizard species (ditto) have a tail that closely resembles their head both in shape and in colouration, and they often move their tail in a manner that deftly mimics the head's movements. The purpose of this deceptive duplication is to confuse predators so that if they do attack, they seize the least important body end (the tail, which can often be regenerated later), rather than the head. This condition thereby constitutes 'pseudo-amphicephaly'. Such species include southeast Asia's red-tailed pipe snake Cylindrophis ruffus, the Indian sand boa Eryx johnii, the Australian stump-tailed lizard Trachydosaurus rugosus (=Tiliqua rugosa), and in particular the so-called worm-lizards or amphisbaenians.

Two Iberian amphisbaenians or worm-lizards Blanus cinereus (Richard Avery/Wikipedia)

In contrast, genuine amphicephalous individuals are rarely if ever recorded (until now?). Probably the best modern-day review of such animals was a paper by Prof. Bert Cunningham of Duke University, published by Scientific Monthly in 1933. His paper considered a selection of reptilian examples of potentially genuine amphicephali.

What an amphicephalous lizard might well look like if such a creature could truly exist  ((c) Dr Karl Shuker)

However, these were mostly collected from medieval bestiaries and other antiquarian writings, which tend not to be the most reliable or scientifically accurate of sources. And certainly, the vast majority of those examples seemed to be either misidentifications of pseudo-amphicephalous species or deliberate fakes. Two, conversely, may well have been the genuine article.

One of these was a supposed amphicephalous snake specimen catalogued in 1679 within the famous natural history collection of the eminent Dutch biologist Jan Swammerdam (1637-1680). Moreover, it was personally observed a year later by another prominent scientist, Dutch physician-entomologist Steven Blankaart (1650-1704) – all of which lends a degree of veracity to this specimen's authenticity.

Jan Swammerdam's reputed amphicephalous snake, drawn by Blankaart and published in 1680

The second example was a lizard with a head at each end, represented by an illustration in Historia Serpentum et Draconum by Italian naturalist Ulisse Aldrovandi (1522-1605), published posthumously in 1640. Aldrovandi is said to have made his drawing from the living animal, which, if true, increases the likelihood of this specimen having been truly amphicephalous.

Aldrovandi's drawing of an alleged amphicephalous lizard

Also worth recording here is a pair of conjoined (i.e. 'Siamese') terrapin twins reported in 1928 by C.H. Townsend. For whereas conjoined terrapins (a fair number of which have been documented down through the years) are generally linked to one another laterally (i.e. side by side) or ventrally (belly to belly), these two individuals were joined to each other posteriorly (rear-to-rear). This yielded a double animal that approached the genuine amphicephalous state. Other, more recent examples of this semi-amphicephalous version of conjoined terrapins are also known.

A semi-amphicephalous example of conjoined terrapins (Matt Rourke)

Returning to the medieval bestiary sources consulted by Prof. Cunningham, these would certainly have referred to the most famous amphicephalous beast of all, albeit one that is entirely mythical – the amphisbaena. Generally categorised as a serpent dragon, i.e. limbless like a snake but dragon-headed (though occasionally portrayed as legged), the amphisbaena had a head at each end of its body, and could therefore move in either direction – sometimes accomplished by grasping one head in the jaws of the other so that its body became a hoop that could roll rapidly over the ground.

An amphisbaena was almost impossible to approach unseen, because only one head slept at a time, the other one staying awake, particularly when this creature was laying eggs. And if an amphisbaena were cut in half, the two segments would promptly rejoin.

Flemish artist Peter Paul Rubens's famous painting 'The Head of Medusa' (c.1617-1618), in which an amphisbaena can be seen (directly below Medusa's head and directly above some leaves at bottom mid-centre of painting) among the diversity of snakes breaking free from Medusa's hair following her death by decapitation - click painting to enlarge it (public domain)

According to Greek mythology, the amphisbaena was spontaneously generated from drops of blood falling onto the desert sands from the severed head of the gorgon Medusa when her slayer, the hero Perseus, flew over Libya with it on his journey back home to the Greek island of Seriphos. Although the amphisbaena's principal diet was ants, it was claimed by some writers to be extremely venomous, and one was blamed for the subsequent death of Mopsus, a seer who was also one of the famed Argonauts that accompanied Jason on his quest for the Golden Fleece.

Amphisbaena reported from Mexico, depicted in Johannes Faber's Thesaurus (1651), but suspiciously similar in form to the amphisbaena depicted by Rubens in his Medusa painting (public domain)

Yet despite its deadly nature, the dual-headed amphisbaena was often cited by early scholars for its medicinal qualities. Sometimes a living specimen was needed, otherwise the skin of one was sufficient. Among the assorted ailments that it reputedly eased were arthritis, chilblains, and the common cold, as well as assuring a safe pregnancy, and keeping warm during the winter if working outside. Eating the meat of an amphisbaena could even attract lovers, and killing one during a full moon would imbue its slayer with great power provided that he was pure of heart and mind.

Amphisbaenas often featured in Mesoamerican and Inca cultures too, frequently depicted with a vertically undulating body, and symbolised eternity. Some of the most spectacular renditions are composed of turquoise mosaic, a stone believed by the Aztecs to emit smoke, and therefore a very fitting mineral for portraying a dragon, especially in versions representing Xiuhcoatl - known variously as the fire serpent or the turquoise serpent. In these New World versions, one head was sometimes much larger than the other, rather than always being identical as in the original Old World amphisbaena.

The turquoise serpent, sculpted from turquoise and pine resin, 15th-16th-Century, Mexico, housed at the British Museum (Sarah Branch/Wikipedia)

In Chile, the oral traditions of the Elqui villagers tell of a 6-ft-long spotted amphisbaena known as the culebrón. During the day, it crawled very slowly upon the ground, but at night it took flight, because, uniquely among amphisbaenas, this version sported a pair of wings

Perhaps the strangest South American amphisbaena, however, was the manora, whose basic form resembled a giant earthworm. Its head and tail ends were indistinguishable from one another, but its body was covered all over with sharp feather-like quills.

Today, the legendary amphisbaena gives its name to a group of real-life reptiles, the amphisbaenians, which are also known as worm-lizards. Their heads are so similar in appearance to their tails that it can be difficult to distinguish which end is which, thus recalling the two-headed amphisbaena of legend.

19th-Century engraving of a spotted amphisbaenian Amphisbaena fuliginosa from Trinidad

Having said that, the legendary amphisbaena underwent a profound transformation during medieval times. It gained not only a pair of legs but also a pair of wings, as well as a clearly-delineated tail – at the end of which was its second head. It also acquired the literally petrifying, gorgonesque ability to turn anyone who looked at it to stone with just a single glance. This advanced version of the amphisbaena is known as the amphisien, and commonly occurs in heraldry.

The amphisien version of the amphisbaena, as depicted in the Aberdeen Bestiary (Aberdeen University Library MS 24)

In modern-day fiction, the most famous amphicephalous creature must surely be the pushmi-pullyu, featuring in Hugh Lofting's beloved series of 'Doctor Dolittle' novels for children (click here for a ShukerNature post devoted to this twin-headed wonder beast). In reality, however, no such animal could exist, because as mammals have a head at one end of their body and an anus at the other, an amphicephalous mammal would lack an anus and therefore be unable to defaecate.

My very own pushmi-pullyu ((c) Dr Karl Shuker)

Surely, therefore, this same argument negates the plausibility of the Logan family's alleged amphicephalous snake too? Not necessarily - because in snakes, being limbless and proportionately very long and slender, the end of the abdominal body region merges entirely into the tail (in mammals, conversely, outwardly the tail appears merely as a slender offshoot from the much broader, limbed abdominal body region). Consequently, the external excretory orifice in snakes (which is actually a cloaca, as it also functions as a genital orifice) is situated not at their posterior pole but about a quarter of the way up from this. Theoretically, therefore, an amphicephalous snake could actually have two cloacae, each positioned some distance away from the opposite head.

What an amphicephalous grass snake Natrix natrix might look like if such a creature could exist ((c) Dr Karl Shuker)

But how might an amphicephalous snake arise in the first place? If due to some developmental malfunction an early snake embryo were to split laterally from the head downwards to nearly the end of the tail, this would yield two almost completely separate snakes. However, they would remain permanently attached to one another because of their undivided (and hence shared) terminal tail portion. Nevertheless, each snake would possess its own fully-formed cloaca-containing abdominal body section. Consequently, this would then be an amphicephalus, and possibly even a viable one (always assuming, of course that such a specimen survived up to birth/hatching).

No mention of cloacal presence has been reported for the Logans' snake, but it will be very interesting to see whether further reports, containing additional details or confirmation of its dual anatomy, emerge in due course. After all, it's not every day that a veritable resurrected beast of classical mythology hits the news headlines around the world.

The amphisbaena awakes? Let's wait and see...so watch this space!

An ornament portraying the amphisbaena of classical mythology (Dr Karl Shuker)