Skip to main content

Holdstock Technical Services

Exploring the World of Electrostatics
Home
About Us
Contact Us
Services
Holdstock Standard Tests
Interesting Articles
Links
Cookies Policy
Member Login
Site map

Giraffe Horns and Lightning


Laurence G. Britton Ph.D., C.Eng., C.Phys.


April 9th, 2009

(Revised August 6th, 2013)

 

Giraffes are the only animals born with horns (they become fully erect during the first week after birth). The horns, known as ossicones, are never shed and neither are their integuments of skin and fur. The tufted horns are located above the level of the untufted ears (Figure 1).

 

Giraffes grow up to 4.5-5.5 meters and typically during this time up to three additional bony horns grow that may be used for fighting between males. The ossicones grow to about 30 cm and have tufts of stiff hair in both males and females. The horns are part of the skull and are replete with veins. The evolutionary purpose of the horns is unknown. As far as the giraffe is concerned, their purpose is solely for engagement in turf battles.


Figure 1: Hairy Tufts on Horns of Reticulated Giraffe

(Photograph Courtesy of Rob Britton)


Giraffe's horns, or ossicones, may offer protection against lightning strikes


According to a 2010 BBC news article wild giraffes are apparently not more prone to lightning strikes than other animals, although one would expect a high frequency of strikes. The reason is unknown:

 

http://www.bbc.co.uk/news/magazine-11734228

 

Giraffes are occasionally killed by lightning, not only in the wild but also in zoos, and exhibit no mitigating behavior to decrease their risk of being struck. Hence, any “lightning protection” provided by their horns should offer a significant evolutionary advantage. Giraffe horns might serve as lightning protection devices for the giraffe by creating a local corona discharge that (1) reduces the electric field gradient in the vicinity of the animal’s head during thunderstorms and hence (2) suppresses upwards streamers that precede lightning strikes.

 

Passive corona charging and discharging devices used commercially often comprise tufts of individual metal wires (Figure 2). The tufted hair on the giraffe’s horns need not be metallic to transfer sufficient current to serve a useful purpose in this regard. Since the ossicones comprise living bone and tissue, exudation of electrolyte-laden sweat could cause the hair tufts to be sufficiently conductive to conduct many microamperes of current in a strong electric field. Protection might thus be afforded against dry lightning in addition to thunderstorms.

 

The “Streamer-Retarding Air Terminal” (US Patent #4,910,636) shown in Figure 2 consists of a “multiplicity of dissipator electrodes comprising the point of the air terminal, an elevation conductor, and a threaded base support”. It is available from LBA Technology (http://www.lbagroup.com/international/lightmas.php).

 

Figure 2: Air Terminal for Lightning Protection


Giraffe horns, or ossicones, bear some similarity to air terminals designed to protect buildings from lightning strikes


The air terminal design bears some similarity to the tufts on a giraffe horn. The similarity is more apparent when considering wild giraffes other than the groomed zoo animal shown in Figure 1. The tuft design and length depends on the species and presumably habitat.

 

A large selection of photos can be found on “Google Images” under “Giraffe Head”. Some of the tufts look remarkably like the commercial device shown in Figure 2, especially those of young giraffes (see Google Images “Young Giraffe Head”) whose tufts can be as long as (or even longer than) the horns themselves. This suggests that the tufts are not decorative and are needed at all stages of a giraffe’s life. It’s plausible that the extra horns grown by adult males serve, at least in part, to compensate for damage suffered by the front pair of horns during horn wrestling, which abrades skin and hair.

 

Most giraffe electrocutions appear to occur when lightning strikes a nearby tree or the ground, especially where small herds are gathered. The electrocution mechanism is different from being directly struck by lightning and the tufted horns offer no protection. First, if a giraffe is close to a tree, side flash can occur whereby the lightning jumps over to the animal and travels to ground. In other cases, current runs through the ground away from the lightning impact point and electrocution is the result of large currents traveling up one leg and down another. The larger the leg spacing relative to the impact point the greater the potential difference between them and hence the larger the current flowing through the body. The leg spacing on a giraffe is short relative to the height of the animal but any marginal protection furnished by this feature is less important than the orientation of the animal relative to the strike point.


Copyright for this article: © 2009-2013 L. G. Britton.