In Part I of this article we reviewed some general points to consider when choosing a substrate – moisture retention, suitability for burrowing and so forth. Today I’ll examine specific types of substrates more closely.
A Note on Substrate Ingestion
We do not fully understand why captive animals sometimes suffer intestinal blockages after swallowing substrates that they likely consume in the wild without incident. It may be related to the consistency of the foods they eat, hydration levels, health or even micro-nutrient intake (for example, Calcium is essential for proper muscle contraction…a deficiency may affect the passage of food through the digestive tract).
Bark absorbs water to a certain degree, rendering it useful for Anoles, Ribbon Snakes and other reptiles that need moderate humidity, but is not as well-suited for amphibians (the edges may be a bit too rough for sensitive skins also). It can also be used dry for arid-adapted species.
Products containing Eucalyptus and Cypress Bark help control odors and may also retard the growth of bacteria, mold and fungi. I’ve long used these, and Hardwood, Aspen Barks, for zoo exhibits and large snakes, lizards and some tortoises. Hardwood Bark is also suitable for small mammals and birds.
Many amphibians are at home in mossy surroundings. Sphagnum Moss is one of the most ideal amphibian substrates of all, and can also be used with certain reptiles (i.e. Crocodile Skinks). It has great water-retaining properties…with a bit of practice you can adjust the moisture level in it and the terrarium quite well.
Burrowing amphibians such as Tiger Salamanders and Smooth-Sided Toads, which would normally utilize soil in the wild, take to Sphagnum readily. I often mix it into topsoil when keeping animals that burrow deeply, such as Giant Bird-Eating Spiders – burrows dug into this mixture retain their shape well.
Sphagnum is also indispensible for creating damp areas within shelters or egg-deposition sites. By wedged it into tree hollows or rolled Cork Bark, you can also create moist hide-aways for Treefrogs, arboreal Tarantulas and other tree-dwelling animals that are usually reluctant to use ground-level caves.
Sphagnum is difficult to swallow, and I have not run across any instances of it having caused an internal blockage. It may begin to grow under the right conditions – spores and seeds within it may sprout as well!
Compressed Frog Moss is an interesting product. It expands when hydrated with water and is excellent as a “crevice-filler” or when mixed into other substrates to bolster water-retention. Some folks use it as an egg-incubating medium as well.
Fine grade, Calcium-Infused Sand should theoretically be harmless or even beneficial if swallowed, but please see the note at the beginning of this article.
Sands of gold, black, white, mauve, orange and other colors allow one to mimic specific habitats when setting up terrariums.
Please see my article Substrates for Animals Prone to Intestinal Blockages for more on this important topic.