Dicpahlism is not a genetically inherited condition, this was proven by San Diego Zoo when Thelma & Louise a dicephalic Corsnsake laid 15 eggs and all hatched into normal neonates and also Zany & Brainy a Californian Kingsnake which laid four clutches of 5 eggs all containing normal hatchlings at Prehistoric Pets in California.

There has been close to a thousand dicephalic snakes recorded in captivity from 169 species in 93 genera from the early 17th century through to the present day. The number of reported cases has risen dramatically over the last years possibly due to the increased interest in keeping and breeding snakes in captivity. The family colubridae has the highest number of instances which if we believe the former statement to be correct isn't surprising as this includes Cornsnakes, Kingsnakes, Milksnakes and Ratsnakes all of which are extremely popular in the hobby. The USA has the most cases (543) with Europe (116) & Asia (101) taking second and third place again this may be a reflection of the popularity of the hobby within these continents.

As mentioned earlier, visually the heads and sometimes the necks are duplicated, heads are not always symmetrically sized and the length of the neck may vary from nothing up to 30 vertebrae or in rare occasions more before the necks fuse with a single spine. Internally other organs may be affected, most commonly affected is the heart and lungs being duplicated. In one case of a Western Diamondback Rattlesnake all internal organs were duplicated down to the small intestines which then joined after one third of their length into a single small intestine, with the remaining viscera being single.

Living dicephalic snakes usually have a dominant head, which feeds, drinks and directs the movement of the snake, in others both heads may eat which presents further problems to the keeper in avoiding food fights, one keeper came up with an ingenious method of making a foam collar that was slipped over the non feeding head whilst the other head ate it's meal, the following weekly feed this method was reversed. Medusa III a dicehalic Black Ratsnake, Patherophis obsoletus obsoletus had an unusual feeding behaviour in that the head that wasn't swallowing the mouse would mimic the actions of the feeding head by preforming  swollowing actions. Some heads seem to learn to cooperate with one another and others are in constant conflict often resulting in the death of the snake.

The majority of dicephalic snakes are either stillborn, dead in egg or only survive for a short time, with only a very small percent reaching adulthood. The longest lived dicephalic Ratsnakes were a Cornsnake called Thelma & Louise that lived at the San Diego Zoo which died at the age of 16 and an equally long lived Grey Ratsnake from the University of Tennessee in Knoxville. Medusa 1 a Gopher snake Pituophis catenifer catenifer holds the record for the longest lived two headed snake who lived just over 22 years at the Steinhart Aquarium, San Fransisco.

An estimated 35 living species are known in the world today with over three quaters of these in the USA.


The following Ratsnake species (past & present Elaphe species) have reported cases of dicephalism:

Elaphe bimaculata, E. climacophora, E. dione, E. quadrivirgata, E.quatuorlineata, E. sauromates, E. schrencki, Euprepiophis conspicillatus; Oocatochus rufodorsatus, Orthriophis taeniurus; Pantherophis alleghaniensis, P. emoryi, P. guttatus, P. obsoletus, P. spiloides, P. vulpinus, Pseudelaphe flavirufa, Rhinechis scalaris, Zamenis longissimus.
From this list the Cornsnake, Pantherophis guttatus & The Black Ratsnake, Pantherophis obsoletus obsoletus has the highest recorded number of specimens, 26 each and The Japanese Ratsnake has had 11 recorded instances.

The most famous of all dicephalic snakes must be 'We' a hermaphroditic (both sexes) Albino Black Ratsnake, The World Aquarium acquired the snake in 1999 for $15,000. Since then the snake has been stolen and then recovered in 2004. In January, the World Aquarium put We up for sale on E-Bay in hopes of raising $150,000, but the sale was stopped due to E-Bays rule of no livestock sales. We was mated with another two-headed albino black rat snake named "Golden Girls." which also hit the head lines but no offspring from this pairing is known. We was adopted by Florida-based biopharmaceutical company Nutra Pharma as its mascot and brand icon, with a six month sponsership deal netting the World Aquarium $15000 which was schelduled for conservation. We died of natural causes at the age of eight years in June of last year.

A couple of the Ratsnake Foundation members that I know of have also hatched or had born dicephalic snakes, Prepiophis had a female Red Backed Ratsnake born and Jan Grathwohl has hatched a Milksnake with two heads.


The techy stuff

A craniodichotomous specimen has two incompletely divided heads, a single atlas and axis, and a single body and tail.
A prodichotomous snake has two complete heads, each with an atlas and axis, either a single or two short necks, and a single body and tail.
A proarchodichotomous specimen has two heads, two long necks, and a single body and tail.
An urodichotomous snake has one head and body but two tails.
An opisthodichotomous specimen has one head, two bodies and two tails.
An amphidichotomous snake has two heads, a single body, and two tails.
Holodichotomy refers to a pair of twins from a single egg