Fevers, light and 'useless' appendixes

By April Holladay for USA TODAY

Q: Do cold-blooded animals develop fevers if sick and how could you tell?

A collard lizard raising its body temperature. U.S. Fish and Wildlife Service

A: Yes, some cold-blooded creatures do develop fevers, in a neat way. They can't control their body temperatures with internal mechanisms as we do. So, lizards, for example, deliberately move into the Sun to raise their body temperature and thus create a fever when they have an infection. They usually get well, then. Moreover, if we stop them from basking, they will likely die.

Fevers help the body fight infection. The immune system gets more active when it's warmer because chemical changes quicken with higher temperatures.

We can't tell if a cold-blooded animal has a fever by detecting a raised temperature. Its body is always the temperature of the air around it or maybe the rock it's basking on — never elevated.

Cold-blooded animals aren't really "cold blooded". Some lizards, in fact, have a higher normal body temperature than some mammals. "Cold-blooded" animals get their heat from outside their body and don't produce it internally. If we pick up a snake on a hot day, it feels warm, not cold. One sunning itself to produce a fever feels the same — warm.

Further Surfing:

•Cornell U.: Recommendations for the Care of Amphibians and Reptiles in Academic Institutions

•California Institute of Technology: Warm and cold blooded animals

•Indiana University: What's a fever for?

•Annals of Internal Medicine: Fever's beneficial effects

Q: What is light made of, if anything at all? Is it actually radiating from its source, or do we just see the source?

A: Light is a form of energy. Light does radiate from a source and that is how we see the source. In fact, light is the only thing we ever see.

John Bortniak, NOAA An aurora lights the sky above the South Pole.

The Sun, a light bulb, a flickering fire — any hot light source — produces light by accelerating electric charges, called electrons. The electrons either change direction or go faster and faster or both. The accelerating electrons create an energy wave (like a water wave) that can exist even in empty space. It's called an electromagnetic wave. Light is an electromagnetic wave.

Run a rubber comb through your hair to charge it with electricity. Now wave the charged comb back and forth to accelerate the charges. You are creating an electromagnetic wave that radiates at the speed of light (186,000 miles per second [300,000 km/s]). You haven't created light and therefore can't see it but you have created an electromagnetic wave. All electromagnetic waves radiate at light speed.

The wave is a self-sustaining disturbance because the electric field creates a magnetic field and the magnetic field than creates an electric one and these two fields continue creating each other indefinitely. It's like a game of leapfrog with the wave zooming off in all directions.

Not all electromagnetic waves are light waves. Visible light has peaks and valleys occurring just often enough (between 400 and 750 trillion peaks per second). Ultraviolet light (black light) has more frequent peaks and infrared light (heat) has less frequent ones. We can't see ultraviolet or infrared light but we still call them light for some unknown reason.

Further Surfing:

•HyperPhysics by Rod Nave: Visible light

Q: Why do we no longer use or need our appendix?

Bartleby.com: Gray's Anatomy The vermiform (means "wormlike") appendix.

A: Your assumption may be mistaken. New evidence suggests we need the appendix to fight infection.

It is true that a whopping 15% of us have had our appendixes removed. In the past, the appendix was little valued (considered a vestigial relic).

Past thinking, however, may be in error.

This narrow muscular 3-inch (8 cm) tube sits at the beginning of the large intestine, like a guard shack. It's crammed with lymph tissue that produces white blood cells — the cells that fight germs. The large intestine teems with mostly beneficial bacteria. The appendix, from its guard-duty site, probably kills hostile bacteria invaders — much as the tonsils do at the back of the mouth and beginning of the windpipe.

Actually, we don't know what the appendix function is yet but we suspect that we do need and use it.

Further Surfing:

•Bartleby.com: The vermiform appendix

•Cells Alive: white blood cells

(Answered Nov. 7, 2003)