Printer Friendly

Canteen for a young lizard.

Some desert lizards are born equippd with a temporary supply of fresh water, report scientists at the University of Arizona in Tuscon. During research on lizard reproduction, Carol A. Beuchat noticed that if the 2-inch-long baby "Yarrow's spiny lizards" were held a little too tightly they would leak a large drop of clear fluid. She was surprised, because the adult Yarrow's spiny lizards have no urinary bladder and excrete a nearly dry form of waste. Beuchat, David Vleck and Eldon Braun have subsequently discovered that baby lizards of this and other desert spcies have an internal sack, or bladder, containing pure water. By a month after birth this bladder shrivels up and becomes a vestigial organ in most species.

The water in this newly discovered "canteen" comprises about 10 percent of the newborn lizard's weight. (Unlike most lizards, Yarrow's spiny lizard bears live young.) Vleck says, ". . . the bladder is essentially a reservoir, and the babies use its water [at least in the laboratory] during periods of dehydration to maintain blood and other body fluids at normal volumes and concentrations."

The role of this bladder in the lizard's natural environment has still not been determined. Vleck says that baby lizards, which have a high surface-to-volume ratio, tend to dry out faster than do adults. But he thinks it most likely that the bladder evolved originally as a means for reptilian eggs to promote water uptake m the soil. Water moves across the shell of a reptilian egg from the side with the higher water concentration to the side with the lower concentration. But if the embryo could temporarily hide some of its water in a canteen, under dry conditions the egg could continue extracting water from the soil, rather than allowing the water to flow out of the egg.

"There is an advantage to having your 'canteen' full at birth," Vleck says. But he argues that its early withering is advantageous to the adults, since a full cantee would be likely to slow a fleeing lizard.
COPYRIGHT 1985 Science Service, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1985, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:some desert lizards are born with a temporary supply of fresh water
Publication:Science News
Date:Aug 24, 1985
Words:335
Previous Article:Animals at the hydrothermal vents.
Next Article:I know how you feel - I think.
Topics:


Related Articles
Leaping lizards and male impersonators: are there hidden messages? By imitating male mating behavior, all-female lizard species apparently enhance...
Do orange lizards wish they were blue?
A walk on the wild side.
Retelling the tale of the two-legged snake.
When Lizards Do Push-Ups.
New lizard ties for `world's smallest'. (Science News of the week).
Littlest lizard. (Freeze Frame).
Mating test pits physique versus domain. (Lizard's Choice).
Gotta run.
Scaly surprises: go behind the scenes of a museum exhibition to learn about scaly lizards and snakes.

Terms of use | Copyright © 2017 Farlex, Inc. | Feedback | For webmasters