The beneficial and fascinating gecko

StoryImage( ‘/Images/Story//Auto-img-11757116393118.jpg’, ‘Photo by Dr. Robert A. Hedeen’, ‘A gecko waits patiently for its next meal (note that a new tail has recently been regenerated).‘);
StoryImage( ‘/Images/Story//Auto-img-117571170129346.jpg’, ‘Photo courtesy of Harris‘, ‘This Madagascar Gecko is one of 800 different species of geckos on a worldwide basis, with about eight found the United States.‘);

Anthropomorphism means endowing lower animals with human traits, and that is all right with me so long it is confined to such creatures as Mickey Mouse, Donald Duck, or Bugs Bunny. But I become irritated when TV commercials aimed at adults star lower animals speaking English and driving snappy convertible cars. Such is the case where a gecko is the star of a commercial that is intended to persuade me to buy the car insurance of a company with a name similar to gecko.

Geckos are lizards that are found in warm parts of the world, and, unlike other lizards who make only a hissing sound, make a grunting noise that to some sounds like “gecko”; hence the name gecko.

About 800 different species of geckos on a worldwide basis, with about eight found the United States. These lizards prefer warm climates, and many of the different ones found in the U.S. have been introduced, especially in Florida. They do not occur naturally north of the Mason-Dixon Line, and are certainly not venomous as some believe.

This is a varied family of reptiles, and it is impossible to make statements, without becoming too technical, that will apply to all of them. However, a majority of them have some interesting things in common. One of these features is that they have an adhesive pad on each of their toes. This enables them to climb smooth, vertical places in search of insects on which they primarily feed. The pads are so efficient a gecko can move across a ceiling in search of prey. The pupils of the eyes are elliptical, and there is no obstruction, bone or otherwise, between the ears. So, if you hold up one of these gentle animals and look in one ear, you can see through the head to the other side. A few other lizards also have this “window” in the head.

Most geckos are nocturnal in habit, coming out of their daytime hiding places at dusk to search for food. I recall an incident that happened some years ago when I was part of a team investigating the movement of a Jungle Yellow Fever vector mosquito northward through Mexico toward the United States. I was staying in the only “hotel” in a small Mexican town, and amused myself one evening by watching a gecko move across the ceiling of the room capturing flies for its dinner. It appeared that the lizard only was attracted to a fly when it moved and would then close in and secure it with its thick, sticky tongue.

In many parts of the world, geckos are encouraged to take up residence in a dwelling where they act as an unpaid exterminator of flies, cockroaches, moths, ants and other household invaders. For this reason, geckos are probably the most tolerated and encouraged group of lizards, and, in some societies, they are considered to be sacred animals.

Geckos are popular as pets and several mail-order companies offer various types for sale along with instructions for their care. Apparently, geckos are rather easy to breed in captivity, and most of the companies offering them for sale state the ones they sell are “home bred” individuals.

As with many other lizards, geckos have a special group of circular muscles around the base of their tail that are used to neatly amputate the tail if caught by a predator. They have no special organs of defense, and it is rare to find a gecko in nature with a complete tail. Once the tail is snipped off, it regenerates itself rapidly. It would be nice if humans also had this power of regeneration in order that a lost arm, leg, finger toe would grow back if severed.

Dr. Robert Hedeen is a former resident of Maryland’s eastern shore and resided in the Chicago area from 1960 to 1971. He is a retired professor emeritus of biological sciences in the University of Maryland system. He has published more than 30 scientific papers, has written numerous magazine articles, and is the author of two books on the natural history of the Chesapeake Bay.

from the April 4-10, 2007, issue

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