The Cyclops of the Animal Kingdom

Cyclops of the X-Men is one comic book superhero that needs no introduction. It would come as no surprise if the creator of this fictional character had actually drawn inspiration from the Texas horned lizard’s (Phrynosoma cornutum) ocular-sinus blood spitting anti-predator defense mechanism. Blood emanates from its inflated eye ducts in jet-like squirts of crimson droplets after a rapid increase in pressure ruptures the sinuses’ thin walls. It can shoot blood up to a distance of 4 feet.

Research indicates canids were more likely to elicit this blood-squirting behavior as compared to other predator type. In an experiment carried out by Middendorf & Sherbrooke (1992), it was also suggested that tactile cues might play a significant role in evoking the autohaemorrhaging response. In addition, the frequency with which the canids were struck by blood on the muzzle and near the eyes was considerably high despite no clear evidence regarding the apparent directionality with which blood was discharged.

Although the specific effect of this behavior remains unexplained scientifically, some researchers conjectured that the blood contains a substance that is noxious to canids and it is some chemical irritant in the blood and not the act of expelling that wards off predators. This was demonstrated in a study whereby kit foxes (Vulpes macrotis) reacted adversely to the blood of the Texas horned lizards, even when delivered in the context of mice prey. The hypothesis made from experimental data stated that the compound in the blood might be derived from detoxifying highly toxic natural venoms of harvester ants (Pogonomyrmex maricopa), which make up the lizards’ primary diet. Considerable doubt remains concerning the issue of blood chemistry, nevertheless, it is undeniable that that this blood squirting behavior increases the lizards’ chances of surviving canid encounters.

Now let us take a look at a “cyclop” in action:

Texas Horned Lizard

Literature Cited/References:

Sherbrooke, W. C. & G. A. Middendorf III, 1992. Canid Elicitation of Blood-Squirting in a Horned Lizard. Copeia, 1992(2): 519-527.

Sherbrooke, W. C. & G. A. Middendorf III, 2001. Blood-Squirting Variability in Horned Lizards (Phrynosoma). Copeia, 2001(4): 1114-1122.

Sherbrooke, W. C., G. A. Middendorf III & E. J. Braun, 2001. Comparison of blood squirted from the circumorbital sinus and systemic blood in a horned lizard, Phrynosoma cornutum. The Southwestern Naturalist, 46(3): 384-387.

Sherbrooke, W. C. & G. A. Middendorf III & M. E. Douglas, 2004. Responses of Kit Foxes (Vulpes macrotis) to Antipredator Blood-Squirting and Blood of Texas Horned Lizards (Phrynosoma cornutum). Copeia, 2004(3): 652-658.

Sherbrooke, W. C., 2008. Antipredator Responses by Texas Horned Lizards to Two Snake Taxa with Different Foraging and Subjugation Strategies. Journal of Herpetology, 42(1): 145-152.

Shuker, K. P. N., 2001. The Hidden Powers of Animals: Uncovering the Secrets of Nature. Reader’s Digest, 2001: 128.

“World’s Weirdest: Blood-Squirting Lizard,” by NatGeo. NatGeoWild YouTube Channel, 30 January 2013. URL: (accessed on 19 Mar 2013).

“DSC_1374a,” by Jerry Oldenettel. Jerry Oldenettel’s Flickr Photostream, 30 September 2007. URL: (accessed on 26 Mar 2013)