The Science Behind Why Spider Ball Pythons Wobble, What’s Really Going On?

This is a gene that has experienced much controversy over the years. It was first discovered and worked with in 1999 by N.E.R.D. It is a co-dominant gene which means it will express phenotypically if inherited, but will also express other genes at the same time. Which is why you will get spider combinations such as banana spiders (see figure 1).

Figure 1: Hatchling banana spider royal python (Python regius) coiling a mouse (Authors own, 2022).

The spider gene becomes fatal if an individual inherits two copies (homozygous), this is why it is not common practice to pair two snakes with the spider gene together to ensure all offspring will only ever be heterozygous (carrying one copy). All individuals who inherit the gene have what is known as wobbly syndrome.

What is wobble syndrome?

The wobble syndrome is considered a neurological issue which affects every royal python with the spider gene, although it is not exclusive to the gene it can also be found in others such as champagne (see figure 2) and hgw (hidden gene woma). The severity of the issue varies greatly.

Some individuals will have a slight head tilt, others will be unable to detect whether they are upside down, unable to move in a straight line experiencing ‘wild’ movements such as side to side or twisting movements of the head, corkscrewing thrashing, unable to hold their heads steady or feed independently such as the inability to strike or constrict (Starck et al., 2022). The severity an individual will suffer when inheriting the gene is not easy to predict, one individual with a head tilt may produce off-spring that cannot right themselves. This makes breeding the gene a lottery gamble for how well individuals will thrive from a slight title to no motor control. 

Figure 2: A champange royal python (Python reguis) (Authors own, 2022).

What causes the wobble?

Until recently this has been a mystery and the wobble is something that has been attempted to be separated from the gene with no success. Scientists carried out a study in 2022 (Starck et al., 2022), setting out to discover the cause of the neurological issues linked to the gene. The sample size was small (wildtype N=5, spider N=4), this was linked to the ethical board and access to materials; Due to the small sample size the study excluded all other morphs except a direct comparison to wild royal pythons as a baseline (expected normal structure) and spider royal pythons. A previous study on royal python ear structures was published and the 3D scanning data was consistent with the wildtype royals within the Starck data set (Christensen et al., 2012). 

There was a distinct morphological difference when comparing healthy ear structures between normal type and spider pythons. The spider morph cross sectional diameter of the semi-circular canal is wider, both the ampullae and the crus communis are inflated in size. The inter- and intraindividual variabilities appear higher in the spider morph snakes. The sacculus within the spider snakes is also distinctly smaller, deformed and locks a coherent macula. Both the sacculus and ampulla are organs involved in equilibrium there is no doubt or surprise that the morphological differences linked to the gene is causing issues with functioning in terms of head tilts, tremors, cork screwing, reduced striking accuracy and righting reflex (Rose and Williams, 2014; Schrenk et al., 2022).

Controversy

The IHS (International Herpetological Society) banned the sale of spider gene royal pythons at the shows in 2018. This was met with shock and anger throughout the hobby within the UK. This brought about large uproar and backlash within the world of snake keeping. This was noticed by outsiders of the hobby. It brought negativity as members of the public who did not work with the gene or snakes in general, were appalled that breeders where defending the morph. One that causes suffering and neurological issues with such severe impacts. 

What was meant to be a step forward in the community just further highlighted and spotlighted the public issues the hobby faces from within. It doesn’t take much to find articles online that are written looking on morph breeding in a negative light “Spider and albino pythons alike, represent an abuse of breeding power” (Nam et al., 2021). Its viewed as animal abuse.

Final thoughts

As a hobby who faces government intervention and negative outsider viewpoints. We must make sure that we are able to self regulate and put our best step forward. Now we are able to provide that the spider gene mutation has negative internal morphological deformities. We must act accordingly and stop breeding these individuals. Welfare should be at the forefront of decisions.

We should have never continued to produce off-spring from individuals who presented wobbles in the first place. As people who are guardians for the lives of all the snakes we keep and produce, what is more important? The vanity aspect of how the snake looks, or its ability to function and thrive? What level of suffering are we going to allow for a snake to have a certain pattern or colour?

References

Christensen CB, Christensen-Dalsgaard J, Brandt C, Madsen PT. Hearing with an atympanic ear: good vibration and poor sound-pressure detection in the royal python, Python regius. J Exp Biol. 2012;215(2): 331–342. 

M. (n.d.). Spider Ball Python Morph problems. Retrieved March 5, 2023, from https://snakesafari.com/post/spider-ball-python-morph-problems/

Nam, P., Chan, Nam, P., David, Nic, Frost, K., & Gray, L. (2021, April). A shaky case for wobbly snakes. Retrieved March 5, 2023, from https://sites.duke.edu/thewellianmag/2021/04/13/a-shaky-case-for-wobbly-snakes/

Rose, M. P., & Williams, D. L. (2014). Neurological dysfunction in a ball Python (python regius) colour morph and implications for Welfare. Journal of Exotic Pet Medicine, 23(3), 234-239. doi:10.1053/j.jepm.2014.06.002

Schrenk, F., Starck, M., Kiefer, I., Flegel, T., Tebrün, W., & Pees, M. (2022). Comparative assessment of computed tomography and magnetic resonance imaging of the spider morph of python regius and wild type python regius to evaluate the morphological correlate of the wobble syndrome. BioRxiv. doi:10.1101/2022.03.24.485672

Starck, J., Schrenk, F., Schröder, S., & Pees, M. (2022, August 15). Malformations of the sacculus and the semicircular canals in spider morph pythons. Retrieved March 5, 2023, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9377635/

Spider – Morph list. (n.d.). Retrieved March 5, 2023, from https://www.worldofballpythons.com/morphs/spider/