Basic invertebrate medicine and sample collection (Proceedings)
This lecture will focus primarily on terrestrial arthropods such as arachnids, myriapods and insects. There is a significant amount of literature available to bring the veterinary clinician up to speed regarding captive management of various invertebrate species. One of the best books the author has run across is "Breeding food animals: live food for vivarium animals". This book covers captive maintenance and reproduction of most species of invertebrates found in captivity. Even so, nothing can top hands-on experience. Therefore the author recommends the interested clinician commit to personally keeping (at least) one of the more common "pet" species. Most of the medical issues in captive invertebrates are due to husbandry issues, therefore this lecture will be heavy on captive husbandry and nutrition information.
Many different options are available for housing captive terrestrial invertebrates ranging from simple pill vials with substrate to elaborate terrariums. As with all captive exotic animals the habitat needs to reflect the animal's natural history in order for it to thrive. Because most invertebrates are not overly destructive, they can be easily maintained in sophisticated terraria. The enclosure does need to be easily maintained as many species will quickly succumb to unclean conditions (especially when contaminated with fungus).The author uses various sized pill vials with holes drilled into the top to house small invertebrate. The plastic aquaria with tight-fitting ventilated lids are ideal for larger animals. In reality, any ventilated enclosure with a tight-fitting lid could be used to house invertebrates. One needs to make sure the material the enclosure is made from is not toxic. Food grade plastics are generally safe, but other plastics can leach toxic chemical into the substrate, especially in a humid environment. With some species such as large tarantulas, millipedes and beetles, the cages need to be very secure as the animals can be strong enough to push lids open or chew through screening or plastic.
Many different substrates are appropriate for captive invertebrates. The selected substrate should allow the animal to behave as normally as possible and still be hygienic. The chosen substrate should not contain pesticides (obviously!), herbicides, fertilizer or other chemical additives. Perlite and other comparable additives should be avoided as well. Organic cactus potting soil and ground coconut shells are favorites of the author as substrates for most invertebrates. Some species, namely centipedes, enjoy a substrate of wet, rotting leaves and other plant material and will feed off it as well.
Provision of a hide area is paramount and the configuration should reflect the natural history of the animal. Some species can be provided with adequate hiding places by placing leaf litter or similar material on top of the substrate. Otherwise, flower pots, plastic containers with holes cut in the side, or commercially produced hide boxes are suggested. Many burrowing species will construct a burrow if given deep enough substrate. This can be frustrating as the animal will rarely be seen. These species will often use an artificial burrow that allows better visualization. Some species of tarantulas are noted for being very "webby" and provide their own hiding areas by casting webbing all over the inside of their enclosure. This is not very attractive or conducive for observing the animal, but if you pull the web structure down they will immediately rebuild it.
Because some invertebrate species are relatively soft-bodied and fragile it is important to choose appropriate terrarium furnishings. Plants and other objects with sharp spines or edges should be avoided. With terrestrial species there should not be furnishings that allow the animal to climb, as it may be injured if it falls.
The most challenging invertebrates to house are those that require high levels of humidity. It is difficult to balance this need for high humidity with adequate ventilation and sanitation. In ideal situations a humidity gradient should be established in the enclosure as it allows the animal exposure to high moisture levels, but allows other areas to dry out. Gradients are easiest to establish with burrowing animals. When provided with a deep enough substrate the lower layers of can be kept moist and the superficial layers can be relatively dry. The animals will burrow and come in contact with the lower, moist layers thus fulfilling the requirement for high humidity.
Most invertebrates do not enjoy bright light and will typically try to avoid it, so any illumination provided is for the benefit of the person viewing the animal. Subdued lighting is suggested if one feels some illumination of the enclosure is desirable. Exposure to natural sunlight or "full-spectrum" lighting is not necessary for invertebrates.