NARWHALS, ALLIGATOR EYES, AND GIANT SALAMANDERS LEAD TO QUESTIONS

by Whit Gibbons

May 12, 2002


In addition to answering a couple of questions I've received on various topics, I want to correct an error I made in a recent column. Actually, I would like to correct all the errors I have made in columns over the years, but no newspaper editor would appreciate having an entire Sunday edition filled in this way, so I will deal with just this one.

The error relates to my attempting to explain why male narwhals, marine mammals of the Arctic seas, have a long tusk. I stated that "when a trait, especially a weapon, occurs only in males, it evolved for one purpose: to fight other males for mates." I appreciate Barry Palevitz of the University of Georgia pointing out two mistakes. "First, evolution doesn't involve forethought, so nothing evolves for a purpose." He's right. "Second, is it clear that male narwhals use their tusks for fighting? They could be just for show, like a peacock's tail feathers. They could serve to intimidate other males rather than be used in actual combat." He is also correct about the general point that apparent weapons may be used in ways other than combat. Although I have seen drawings of male narwhals engaged in what looked like fighting, I am not aware that anyone has actually confirmed that the tusks are used for fighting and not just for display.

I will try to get the answers to the following questions right.

Q. - I have a pregnant girl staying with me who has an iguana. Should she be cautious handling this creature because of Salmonella?

A. - Salmonellosis is a disease caused by bacteria called Salmonella. Pet iguanas have been implicated as a source of Salmonella in some situations. Salmonella is generally a bigger problem for young children than adults, but pregnancy is always a time to be extra cautious about potential problems from biological and chemical hazards. You should check with a health clinic or medical facility for details about potential problems with Salmonella and make the assumption that with an iguana around there is some risk of exposure. The CDC (Centers for Disease Control and Prevention) Web site (www.cdc.gov) provides information about the risks and hazards of salmonellosis and other ailments.

Q - My 8-year-old presented us with a question that I can't seem to find the answer to. She heard that male alligator's eyes are red, while the female's are not. Could you clarify or link me to a site that could answer this question?

A - The eyes of male and female alligators are yellow with a black pupil. What she is probably referring to is the eye shine or reflection at night from a flashlight. The reflected color can range from deep ruby red to orange to yellow. The reflection is visible more than a hundred yards away. The eyes of big alligators seem to me more likely to appear deep red whereas smaller ones are more often yellow, but this can vary. Male alligators get bigger than females, but no inherent difference exists between the eyes of males and females that I am aware of.

Q. - I would like to contact anyone who has seen, has a photo of, or can tell me anything about a giant salamander from the Trinity Alps in California. The salamander is said to be from five to eight feet long. I have also heard that they do indeed exist.

A. - The largest known salamanders in North America are aquatic species that live in the east. The bulkiest is the hellbender of mountain streams, with a record length of two and a half feet. The greater siren of the Southeast reaches lengths of over three feet. The largest American salamander, the two-toed amphiuma, has a record length of almost four feet. The world's largest salamander, from Japan, is closely related to the hellbender and gets more than five feet long. As the Trinity Alps are in northern California, people may be referring to the Pacific giant salamander, the largest terrestrial salamander in the country. Some approach a foot in length, but any salamander much larger from the western states would be worth reporting to the nearest zoo.



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