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

 

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.

Last time I reported on the Staten Islands Zoo’s use of the Zoo Med 10.0 High Output UVB Lamp (Please see Part I of this article). Today I’d like to provide some specifics concerning tests carried out there.

Test Results
The UVB output readings recorded at the Staten Island Zoo are as follows (note: measurements are expressed in microwatts per centimeter squared, the standard for measuring UVB output):

Zoo Med Reptisun 10.0 High Output UVB Lamp

Distance	Without Screen	Through Screen
6 inches	75	56
12 inches	23	18
18 inches	10	8

Zoo Med Reptisun 5.0 UVB Lamp

Distance	Without Screen	Through Screen
6 inches	32	24
12 inches	9	7
18 inches	4	3

As you can see, the basking site’s distance from the lamp has a major impact upon UVB exposure, as does the screen cover’s deflection of light rays. With a bit of creativity, basking spots within 6 inches of the lamp can be arranged in most situations, and this is certainly the way to go for many species. Where safe to do so, dispensing with the screen cover is another option.

Using a Separate Basking Enclosure
If a 6-inch basking site or uncovered top are not feasible in your pet’s terrarium, consider the possibility of utilizing a separate basking enclosure for a few hours each day. When keeping young radiated and star tortoises in high-topped zoo exhibits, where adequate UVB exposure was not possible, I rotated the animals into a low, uncovered container every day or so, and achieved excellent results.

If you go this route, be sure to keep your pet’s individual needs and temperament in mind. For example, a simple, open container that might suit a Greek tortoise would likely cause a good deal stress to a flat-rock lizard. High strung or secretive animals must be made to feel secure in the basking enclosure, or you may do more harm than good.

Reflectors and UVB Output
The group UV Guide UK has found that simply mounting the lamp within a metal reflector nearly doubles the UVB light that is available to basking animals. In addition to focusing all of the lamp’s light into the terrarium, I imagine that the reflector also helps by deflecting back some of the light that has bounced off screen tops or other structures.

 

An informative article on the role of UVB and basking behavior in Vitamin D synthesis is posted at:
http://www.uvguide.co.uk/vitdpathway.htm

Click: My Animal Collection: How a Herpetologist Keeps American Toads, Bufo (Anaxyrus) americanus and Related Species, Part I, to read the first part of this article.

Temperature

American toads are, in contrast to many amphibians, quite resilient in terms of temperature tolerance.   However, they do best at moderate temperatures, and in the heat of summer will attempt to burrow below the substrate.  Mine are kept at room temperature, which ranges from 62 F in winter to 78 F in the summer.  During particularly hot spells, I move them to an air conditioned room or the cool basement.

Naturalistic and “Hybrid” Terrariums

Toads also adapt well to planted, naturalistic terrariums.  A substrate of top soil and peat moss will allow them to construct burrows, which will be used repeatedly by the same animals.  Cover the soil with one of the moss-based products listed above and dead leaves in order to retain moisture.

A “hybrid” type set-up combines certain features of both styles described above.  A substrate of smooth aquarium stones (1/2 inch size or larger, to prevent ingestion) allows for live plants but deters burrowing (see photo).

R-Zilla Rock Dens serve well as shelters in such terrariums, or you can create your own using cork bark or rocks.  When designing rock caves, consider that the toads may injure themselves if able to burrow and collapse the structure.  Exo-Terra Terrarium Plants are extremely life-like and can be used to good effect in naturalistic terrariums as well.

A Terrarium for Public Display

I designed the gravel-base terrarium shown in the accompanying photo for a museum in New York City.  Zoo-Med Terrarium Moss is mixed into the gravel, which itself sits on an Under-gravel Filter Plate.  A drain cut into the tank’s glass bottom allows the entire terrarium to be hosed down.  A water reserve is kept below the under-gravel plate, creating a damp but not wet environment for the resident toads and salamanders.

Feeding American Toads and Their Relatives

Wild Caught Invertebrates

From spring through fall, I feed my toads exclusively upon wild-caught invertebrates.  A Zoo Med Bug Napper yields plenty of moths and beetles, and easily meets their needs.  However, I enjoy poking around, and so also collect tree crickets, sow bugs, harvestman (“daddy longlegs”), millipedes, termites, earthworms, field crickets and caterpillars whenever I am able.  I feed the toads just about every day during the summer (2-3 small insects each) and 2-3 times weekly when temperatures drop.

I avoid spiders, fireflies, ladybugs and brightly-colored insects, due to possible toxicity problems, and do not collect for a week or so after the area has been sprayed to control West Nile virus.

Commercially Available Insects

During the winter, I keep breeding colonies of sowbugs, earthworms and mealworms as a food source for my collection (regarding mealworms, feed toads only newly molted, or white grubs, and beetles).  The balance of the diet is made up of crickets, roaches, waxworms and butter worms.

Training your pet to tong-feed will go a long way in helping you to introduce dietary variety.  By doing so, I have been able to add Zoo Med Canned Caterpillars and Grasshoppers to my toads’ diets.

I powder feeder insects with a Tetra Repto Cal Supplement once weekly during the winter.  I’ve found that such is unnecessary in summer, when wild caught invertebrates dominate the diet.

Some Thoughts on Prey Size

I have always believed that American toads are designed, by mouth structure and feeing behavior, to take smaller-sized prey than do similarly-sized frogs (i.e. the green frog, Lithobates clamitans).  Even when feeding adult toads, I rarely use insects larger than a ½ to ¾ grown cricket.  Toads under my care are still thriving in their late 20’s and, while I cannot document such, I believe that prey size may be a contributing factor.

 

I’ve written other articles on toads and on amphibian care in general.  Please check out the following when you have a chance:

Canned Insects and other Invertebrates – An Important New Food for Pet Reptiles and Amphibians

Making the Most of the Mealworm: some tips on enhancing the nutritional value of this pet trade staple

Providing a Balanced Diet to Reptile and Amphibian Pets – approaches to consider

Terrestrial Isopods (Sowbugs, Pillbugs, Potato Bugs) As Food for Captive Reptiles and Amphibians

The Marine Toad, Bufo marinus (recently re-classified as Rhinella marina) in Nature and Captivity – Part I, Natural History

Today’s article is the second in a series concerning animals in my own collection.  For additional information concerning this line of articles, please see My Animal Collection: How a Herpetologist Keeps Barking Treefrogs (Hyla gratiosa) and Gray Treefrogs (Hyla versicolor).

Note: the following information is also largely applicable to other toads that commonly appear in the pet trade, i.e. the Great Plains toad, B. cognatus, the Gulf Coast toad, B. valliceps, the southern toad, B. terrestris, Woodhouse’s toad, B. woodhousei and the Texas toad, B. speciosus.  Fowler’s toads and the various Spadefoot toads prefer arid substrates…I’ll cover the care of both in the future.

Most North American toads in the Genus Bufo have been recently reclassified within the Genus Anaxyrus, but not all herpetologists agree on this point.

An Ideal Terrarium Pet

As with many of the animals I favor, American toads have much to offer the hobbyist but are not as popular as some of their more colorful relatives (actually, they vary greatly in color – I have run across yellow, reddish and nearly black specimens in the field).

Perhaps because they are so well- protected by virulent skin toxins, American toads are calm and confiding in captivity.  They usually take on diurnal habits, and even wild caught adults will feed from the hand in short order.  Pardon the stretch, but their behavior brings to mind that of the striped skunks I have kept.  Skunks seem to know that they are “untouchable”, and hence are very approachable (even in the wild)…toads are much like that, at least in my mind!

They are also quite intelligent and responsive – please see my article entitled “Amphibian Learning Abilities – the Southern Toad, Bufo (Anaxyrus) terrestris and Bumblebee Mimics” for further details.

Designing the Terrarium

I currently keep 2 yearling American toads in a Tom Aquarium Jumbo PLA-House Plastic Terrarium.  This terrarium’s ventilation ports assure adequate air exchange (despite favoring moist habitats, toads and other amphibians fare poorly in stagnant air) yet are small enough to prevent small feeder insects from escaping.  This set-up is dismantled and cleaned weekly – the terrarium’s light weight simplifies this chore.

Substrate

The substrate pictured in the photo is R-Zilla Compressed Frog Moss.  American toads prefer a drier environment than do most frogs, so I use only ½ to ¾ of the amount of water called for in the instructions when preparing the moss (the moss is packaged dry, and must be reconstituted).  Hagen Exo-Terra Plume Moss and Zoo Med Terrarium Moss are also good choices for toads and other amphibians.

In this terrarium, the substrate is rinsed or spot-cleaned once mid-week and replaced weekly.  As with most amphibian terrariums, I use only hot water to clean, with bleach or table salt added when something stronger is called for.

Water

The terrarium is sprayed once daily with de-chlorinated water.The toads also frequently soak in their water bowl…just bear in mind that they are poor swimmers, so provide an easily-exited container for their pool.

Terrarium Decorations

I set up the terrarium in manner that encourages easy visibility and feeding- time interactions.  This is not always possible with amphibian pets, of course, as secretive species will languish and die if unable to hide.  American toads take to it readily however, and so observations, feeding and cleaning are much simplified.  In this terrarium the toads have become quite tame – noticing when I enter the room hopping forward in anticipation of a meal.

I provide a Zoo Med Turtle Hut or a Cork Bark Hollow as a retreat, but the toads are more often to be found on top of it, scanning the moss for insects or, it seems, watching the room in general.

Light

The PLA-House Hood Light fits right onto the terrarium’s lid, and is useful for providing additional illumination without excess heat.

In planted terrariums, a Reptisun 2.0 Florescent Bulb will provide sufficient light for plants without exposing the toads to harmful levels of UVB – most amphibians have UVB “filters” in their skin, and actively avoid the sun.

Click: My Animal Collection: How a Herpetologist Keeps American Toads, Bufo (Anaxyrus) americanus and Related Species, Part II to read the rest of this article.

 

 

Today I’ll introduce a member of a group of insects that have long fascinated me – the stick insects, or walking sticks. Several of the over 2,700 described species are well established in captivity, especially among European hobbyists. They are growing in popularity here in the USA also, most commonly, I’ve noticed, among reptile and amphibian keepers. (Note: laws governing the keeping of insects vary from country to country and state to state; please check those applicable to you before purchasing insect pets).

Ants as Babysitters

Today’s insect hails from Australia and New Guinea (as do most truly bizarre creatures!). I’ll cover the husbandry of the giant spiny stick insect in the future…for now I’d like to provide you with a look at its most incredible reproductive strategy.

Female giant spiny stick insects lay approximately 12 eggs at a time, and may produce up to 1,000 or more during their lives. They fall to the ground after being quite forcibly ejected by the cloaca.

The eggs resemble seeds and are tipped with a structure known as a capitulum. The captiulum’s collar is a favored food of ants of the genus Leptomyrmex. The ants carry the eggs into their nest, where the collar is eaten. The stick insect’s eggs are then discarded in the ant colony’s underground rubbish pile, where, protected from predators and the fires that regularly ravage the forests above, they develop.

Tricking the Ants

The walking stick nymphs mimic Leptomyrmex ants in color (black body, red head) and move about in a rapid, frantic manner as do the ants (adult stick insects are slow moving). They also curl their abdomens up over the body, in the manner of their ant hosts.

Upon leaving the ant nest the stick insects moult, assume the adult body form and coloration, and climb into trees to live. All walking sticks undergo incomplete, or hemimetabolous, metamorphosis – there is no pupae stage.

A Variable Path to Reproduction

This species may reproduce either sexually or by parthenogenesis. Eggs produced via mating hatch in approximately 4 months, while those produced via parthenogenesis may take 9 months or more to hatch.

Strange, even for an insect, don’t you think? I’m always interested to hear about unique survival strategies…please write in with your own favorites and I’ll share them in future articles.

You can read more about this and related stick insects at:

http://www.novelguide.com/a/discover/grze_03/grze_03_00194.html#Macleays_spectre

Image referenced from Wikipedia and originally posted by Stephan M. Hohne

http://en.wikipedia.org/wiki/Image:Extatosoma_tiaratum_114.jpg