The Coral Snake: "Red on Yellow Kill a Fellow"

Forrest M. Mims III

Each year since 1993 I have taught a college course on atmospheric science in Hawaii , the land of no snakes. So it was rather ironic to encounter a brightly colored snake in the driveway minutes before leaving for the annual teaching stint in Hawaii a few years ago.

Only a few snakes are decorated by colored rings of red, yellow and black. One is the harmless milk snake. The other is the coral snake, and that is what was slithering across the driveway a few feet away.

The old saying “red on yellow kill a fellow” made identification easy. The yellow bands around the snake were bordered by red bands.

While we've seen a fair number of coral snakes out here in the country, I've never been able to get a good photograph of one. That's because all the previous coral snakes were spotted along the trails in the woods, from where they quickly flee when spotted.

But this snake was in driveway country, so I quickly grabbed a camera and went to work.

Figure 1. This coral snake visited the Mims place on a recent morning. Photograph by Forrest M. Mims III.


Aside from its beautiful coloration, the most obvious feature of the coral snake is its small head. That's good, for this leaves much less room inside for the long fangs and the large poison glands of a rattlesnake, water moccasin and copperhead. These are the other three kinds of poisonous snakes in the US. They can inject substantial venom when they bite, but the coral snake has much smaller fangs and must chew to inject its venom.

The venom of a coral snake is potentially more toxic than that of other poisonous snakes in the US. In fact, coral snake venom closely resembles the venom of cobras and other highly dangerous snakes.

According to Dr. Robert Norris of the eMedicine web site, around 20 people are bitten by coral snakes each year. Yet there have been no coral snake fatalities in the U.S. since antivenom was introduced. Prior to that, around 10 percent of victims died.

Dr. Norris's article on coral snakes and the treatment of their bites is worth reading. So is the Texas Parks and Wildlife web article “Venomous Snake Safety.” This article reports that Texas coral snakes are usually no more than 76 cm (30 inches) long, which was the length of our recent visitor. Last fall, I nearly walked over one by the creek that was a good 90 cm (36 inches) long.

Venomous snakes found in the US and elsewhere are described in many web sites, including this brief introduction. In the US, various State agencies and organizations publish information about venomous snakes. Much of this information can be found in a quick web search. For example, the people at Texas Parks and Wildlife are concerned about the future of Texas snakes. Their article “Venomous Snake Safety” pleads, “Please do not kill a snake--even a venomous one--they serve a valuable function in the environment. The majority of bites result from people taking unnecessary or foolish risks with venomous snakes.”

Young children must be carefully supervised in places where venomous snakes might be present. And never go outside at night without a flashlight. A venomous snake that might otherwise stay away might strike the foot that steps on it.

Forrest M. Mims III and his science are featured online at www.forrestmims.org and www.sunandsky.org. Follow his science at twitter.com/fmims. "World of Science" columns are selected and sometimes revised from columns published in the San Antonio Express-News or the Seguin Gazette-Enterprise. The columns are intended for a general audience.
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The Citizen Scientist (04 June 2010).