That Reptile Blog – Reptile, Amphibian and Exotic Pet Care and Information

An article published in the June 30, 2008 issue of The Proceedings of the National Academy of Sciences documents a heretofore unknown vertebrate life-history strategy…2/3 of the Labord’s chameleon’s life is spent within the egg.

Native to southwestern Madagascar, this tiny lizard lives for only 4-5 months, after an incubation period of 7-9 months.  The entire life cycle is synchronized to an extraordinary degree, with nearly all members of the species hatching, breeding and dying in concert.  Uniquely for a lizard, no adults survive until the next generation hatches…all individuals hatch in November, mate in January, and die shortly thereafter.  The time period from conception to death – usually less than 1 year – is perhaps the shortest known for any vertebrate.

Researchers are trying to identify the genetic or hormonal process that regulates the lifespan.  An understanding of this phenomenon may point to ways of controlling cell death in humans.

You can read about field research projects dealing with this and related chameleons at:

http://www.madagasikara-voakajy.org/en/reptiles_and_amphibians

The 60+ species of sea snakes – brightly colored, highly venomous relatives of the cobras, mambas and coral snakes – are little studied and not often seen in zoos.  I was fortunate enough to have worked with yellow-bellied sea snakes (Pelamis platurus) at the Bronx Zoo, but the species is no longer exhibited there (perhaps something to do with the preferred diet of live moray and American eels?).   If you have the opportunity to visit a zoo that keeps sea snakes, by all means do so – you will not be disappointed.

How Marine Snakes Find Fresh Water

A recent Physiological and Biochemical Zoology article, written by noted herpetologist Harvey Lillywhite, dispels a popular belief concerning marine snakes.   Sea snakes, it seems, do not use special glands to extract salt from sea water, thus rendering it drinkable.  These glands remove excess salt from the bloodstream, but the snakes can drink only fresh or very dilute sea water.

Research focusing on the black-banded sea krait (Laticauda semifasciata) showed that the snakes obtain all their drinking water from fresh water springs (sea kraits leave the water on occasion), and refuse to drink sea water even when dehydrated.  The majority of other sea snakes, which do not travel overland, are presumed to drink from the surface layer of fresh water that develops on the ocean when it rains.  Indeed, sea snakes reach their greatest diversity in regions with heavy rainfall, and sea kraits are most common near fresh water spring outflows.

Notes on Marine Reptiles in North America

The study seems to raise questions as to the drinking habits of other marine reptiles, such as sea turtles.  It brought to my mind time spent observing mangrove salt marsh snakes (Nerodia clarkii compressicauda) in Florida – that particular snake lives largely in salt water, but periodically travels to nearby fresh water swamps to drink.

At the mouth of the Nissequogue River on Long Island, NY, I encountered a population of snapping turtles (Chelydra serpentina) that have been documented as having salt-excreting glands not possessed by snapping turtles living further upstream in the same river.  I’ll soon review an article written on the turtles in that habitat, with a view towards reconciling it with this surprising new information.

You can read more about the natural history of sea snakes and sea kraits at the web site of the Chicago Field Museum:

http://www.fieldmuseum.org/aquaticsnakes/true_sea.html

Image referenced at Wikipedia, http://en.wikipedia.org/wiki/Image:Banded_Sea_Snake-jonhanson.jpg, and originally posted by Jon Hanson on FlickR.

We have learned a great deal about the Ultraviolet B (UVB) light requirements of reptiles in recent years. However, the actual process of providing our pets with UVB of the correct wavelength (290-315 nanometers) remains fraught with confusion.

While helping to set up the new reptile house at New York City’s Staten Island Zoo (former stomping grounds of famed herpetologist Carl Kauffeld), I spoke with several pioneering researchers in the field of reptile UVB requirements, and have since monitored the building’s exhibits.

Recent Tests at the Staten Island Zoo
Recently, the zoo’s reptile keepers ran some tests in order to measure the UVB output of fluorescent lamps (bulbs) used in some of the exhibits and holding cages. While mercury vapor lamps often provide more UVB over a greater range, they are sometimes unsuitable for small cages, or for use with certain species. This study focused on fluorescent lamps, which are commonly used by pet keepers as well.

Using a UVB meter, the staff found that the Zoo Med Reptisun 10.0 High Output UVB Lamp provided high levels of UVB, with the Zoo Med Reptisun 5.0 UVB Lamp being valuable in some situations as well.

Earlier Research on Zoo Med Lamps
I did a bit of research, and learned that a group known as UV Guide UK (please see below) had earlier cited research showing that the Reptisun 5.0 (the 10.0 was not tested) scored highest of all fluorescent tubes in what is known as the D3 Index (the projected ability of lamp to foster Vitamin D synthesis). UV Guide UK also found that the Zoo Med 10.0 and 5.0 lamps lead other fluorescents in UVB output.

Zoo Med Lamps on Lizard Exhibits
The Staten Island Zoo currently uses the Zoo Med 10.0 High Output UVB Lamp with a number of lizards, including such sensitive species as the crevice spiny swift (Sceloporus poinsetti) and the Texas horned lizard (Phrynosoma cornutum).

Check out the specifics of the UVB output readings recorded at the zoo, and take a look at a simple method of increasing the output of any UVB lamp at part II of this article.

You can read more about the work of UV Guide UK, including the tests mentioned, at the following site (Note: the original tests were in 2005…the Zoo Med Lamps have been upgraded in the interim).

Socially Influenced Mating behavior
Ever wonder how a male frog might draw the attention of a female when he is calling amid hundreds of others? Research published in the August, 2008 “Journal of Comparative Psychology” has revealed that gray treefrogs vary their calls in response to social situations. When alone or in small groups, males utilize the species’ usual call. However, when trying to attract a mate amid large groups, males will vary the rhythm of their calls, in order to stand out from the crowd.

The Only Ultrasonic-Sensitive Frog
Concave-eared torrent frogs have, as one might guess from their name, recessed eardrums. Biologists looking into why this species’ eardrums are not level with the skin, as in most other frogs, discovered that these natives of central China emit and hear ultrasonic mating calls. This is likely because noise from the rushing streams along which they dwell would drown out calls emitted in the lower sound ranges (which are used by most frogs). Until now, only bats, whales and certain insects were thought to utilize ultrasonic calls.

Unusual Ears
And why the recessed eardrums? As stated in an article published in the May, 2008 issue of “Nature”, the torrent frogs eardrums are only 1/30th as thick as the eardrums of other frogs (which are, I imagine, quite thin themselves!) – an adaptation to allow the detection of ultrasonic sound. Their recessed location is thought to confer some protection against injury.

You can learn more about the concave-eared torrent frog’s natural history at:
http://amphibiaweb.org/cgi/amphib_query?where-genus=Odorrana&where-species=tormota

Image referenced from Wikipedia, http://en.wikipedia.org/wiki/Image:Hyla_versicolor.jpg, and taken by LA Dawson

A newly discovered bacteria species (Deviriesea agamarum) is responsible for a variety of fatal organ diseases that currently plague captive lizard populations, according to an article in the September, 2008 issue of The International Journal of Systematic and Evolutionary Microbiology. Particularly hard-hit has been a breeding program for the highly endangered Oman dab lizard, Uromastyx thomasi, but a number of other desert-dwelling lizards in the genera Uromastyx and Agama are susceptible as well. The bacterium is related to others that cause human skin infections.The identification of the bacterium has important implications not only for the treatment of disease in captive lizards, but also for wild populations. Captive-bred reptiles that are used in reintroduction programs may appear healthy but harbor diseases that can decimate wild populations. Some years ago, this very situation caused serious respiratory disease outbreaks among desert tortoise populations in the American southwest, and led to a ban on the release of confiscated tortoises. Similarly, the September 23, 2008 issue of Current Biology states that many amphibian species in Europe are currently threatened by a fatal Chytrid fungus that was introduced to the wild by Mallorcan midwife toads released as part of a reintroduction effort.

You can read more about disease problems that affect reintroduction programs at:
http://esciencenews.com/articles/2008/09/22/captive.breeding.introduced.infectious.disease.mallorcan.amphibians.0