Bark Scorpions (Centruroides)

Bark Scorpions

By Dean Gramcko

Bark scorpions are a unique and fascinating group of scorpions indigenous to the Americas that are ideally suited to captive care in the vivarium. In America, the term Bark scorpion commonly denotes members of the genus Centruroides, a genus of Buthidae with between 70 and 80 species (different authorities disagree on certain species status). The genus Centuroides is an American taxon spanning the United States, Mexico, and Central America with established populations in South America and the West Indies, and smaller introduced populations in Africa.

The species of this genus are non-burrowing and hide among leaf litter, under stones or wood, among dead or living vegetation, or in the folds of plants or tree bark. Many species find their way into human habitations in their native areas. They are light bodied and agile,0 and able to climb vertical surfaces or cling upside down to rough surfaces as they walk.  A number of Centruroides species have very potent venom. Due to their defensive nature and frequent encounters with humans some Centruroides species are responsible for numerous deaths or dangerous envenomations in their native countries. C. exilicauda, C. sculpturatus, C. limpidus, C. noxius, and  C. suffusus all possess venom documented as having caused humans deaths, other species within the genus may possess medically significant venom. Many species within the genus possess venom capable of inflicting strong pain, but are not considered to have particularly toxic venom. Any species of Centruroides must be kept in an escape proof cage. A tight fitting lid is a must for any enclosure, as small gaps between lids and enclosures can provide perfect opportunities for escape. Some keepers apply a band of petrolium jelly around the upper lip of  the cage to help prevent young or small specimens from escaping.

Bark scorpions, like many Buthids, have a relatively short life cycle when compared to many other species. Specimens of C. guanensis may reach maturity in as little as 6 months, (most groups of scorpions take at least 1 to 2 years to mature, some species take much longer). They, as a group, are generally short lived with reported lifespans of between 1 year (C. insulanus) and over 4 years (C. gracilis). Most species within the genus Centuroides do not have established longevity records, but with maturation taking up to 3 or 4 years in C. vittatus, it is not unlikely that some specimens within the genus might live 6 years or more.

Bark scorpions are well suited to life in a vivarium. They are small in size (many measure less than 3” in length) and are one of few types of scorpions that can be housed communally with minimal chances of cannibalism. They are active hunters and as they do not burrow they are an ideal species to observe in the evenings. Most Centruroides species kept in captivity have proven to be prolific, and usually if males and females are housed together under proper conditions for long enough they will produce offspring. Bark scorpions are iteroparous and may give birth to between 1 and 4 clutches after a single mating, 2 probably being about average.

Bark Scorpion Tank

3 commonly available species are:

Centruroides sculpturatus: commonly called the Arizona Bark Scorpion, C. sculpturatus is generally considered to have the most potent venom of any U.S. scorpion, and while deaths are rare, it is the only U.S. scorpion that is well documented as having caused deaths not related to allergic reactions. It was formerly considered to be the same species as C. exilicauda, a Mexican species of bark scorpion now considered to be a separate species.

Centruroides vittatus: commonly called the Texas Bark Scorpion or Striped Bark Scorpion,  this is a distinctively marked species that is frequently available and common in the U.S.

Centruroides gracilis: This scorpion likely hails from Central America originally but has well established populations in Florida in the United States as well as Islands in the Caribbean. It is among the largest bark scorpions with adults measuring from between 4 and 6 inches.

Most species of bark scorpions kept in captivity do well under relatively similar conditions with varying temperature and humidity depending on species. Most specimens will thrive in a terrarium when given stacks of cork bark or stones to hide under. Care should be taken to ensure that cage furnishings will not shift and crush any scorpions. Live plants such as bromeliads or non-spiny succulents can improve the look of the enclosure (any plant used should be identified and researched to ensure it doesn’t present a threat to the scorpion), and provide hiding places for the scorpions. Water should be provided to any species at all times in a dish shallow enough to ensure scorpions do not become trapped and drown. Adding gravel to smooth bottomed dishes can help to guard against drowning. Most bark scorpion do well under similar temperature ranges (75 – 87 Fahrenheit). Most species do not require high humidity levels. Misting the enclosure lightly once weekly or bi-weekly depending on species is recommended.

Baby bark scorpions can be housed either in the larger enclosure with the adults, (though adult scorpions may sometimes cannibalize the young) or separated and raised up in small deli cups. The author prefers individual deli cups as it allows more precise control of temperature and humidity and eliminates any chance of predation from larger cagemates. Juvenile bark  scorpions development is measured most commonly with the term “instar” (referring to the stage of development present between two molts).

A newborn scorpion is termed “1st instar”. Upon completion of it’s 1st molt it is considered “2nd instar”.  The precise number of molts preceding adulthood varies between species and sometimes between genders of the same species. Generally bark scorpions seem to mature at around their 6th or 7th molt which for most Centruroides species occurs within 1 or 2 years (though some species may take much longer).

Their semi-arboreal nature, ability to live communally, and their readiness to reproduce in captivity make this group of scorpions fascinating to keep and an ideal candidate for observation in a vivarium. While the lifespan of individual scorpions are relatively short, these communal scorpions can be set up in large breeding colonies that will bring satisfaction to their keeper for years.

References:

Francke, O.F.  & Jones, S.K., 1982. The Life History of Centruroides Gracilis (Scorpiones, Buthidae). The Journal of Arachnology, Vol. 10, pp. 223 – 239.

Polis, G. & Sissom, W.D., 1990. Life History. In G. Polis (Ed.), Biology of Scorpions (pp. 161 – 223). Stanford, CA: Stanford University Press.

Rein, J.O. & Teruel, R., 2012. The Scorpion Files. Retrieved from http://www.ntnu.no/ub/scorpionfiles/c_gracilis.php

Sissom, W. D., 1980. Life Histories of Two North American Scorpions: Centruroides vittatus (Say) (Buthidae) and Vaejovis bilineatus Pockock (Vaejovidae). Masters dissertation. Texas Tech University, Lubbock, TX.

Stahnke, H.L., 1971. Some Observations of the Genus Centruroides Marx (Buthidae, Scorpionida) and C. Sculpturatus Ewing. Entomological News, Vol. 82, pp. 281 – 307.

Stahnke, H.L. & Calos, M., 1977. A Key to the Species of the Genus Centruroides Marx (Scorpionida: Buthidae). Entomological News, Vol. 88,  pp. 111 -120.

Entomological Etymology – Correction

ENTOMOLOGICAL ETYMOLOGY

CORRECTION
By Kevin Scott

In the last issue of The Reptile Times, the spiders belonging to the genus Poecilotheria were erroneously referred to as ornamental baboon spiders. Baboon spiders belong to Harpactirinae, a subfamily of Theraphosidae(tarantulas) from Africa. This subfamily was first set up by Reginald Pocock in 1897 to include species in the genera Ceratogyrus and Pterinochilus [1].  The accepted common name for the Poecilotheria genus is simply “ornamental spiders,” excluding the word ‘baboon.’ The scientific names used in the last issue were correct as of the date published.correction

NOMENCLATURE

In the world of invertebrates, it is particularly important to use correct nomenclature in order to avoid uncertainty with respect to a species’ identity. Stanley and Marguerite Schultz claim that the nomenclature of tarantulas “can euphemistically be described as confused,” in their book The Tarantula Keeper’s Guide. Much of the confusion stems from misidentification during importation as well as the misuse and misspelling of names. I generally prefer to use the scientific names of spiders to avoid confusion, but even so, there can be some uncertainty in terms of the most common revision of classification.

COMMON DESCRIPTORS

One problem with common names is that they are often descriptive, and could in principle apply to several species. For example, Nhandu coloratovillosum is commonly referred to as the Brazilian black and white tarantula. Acanthoscurria geniculata is also a tarantula from Brazil that has black and white coloration, but the common name for this one is Brazilian giant white knee. Furthermore, although these two species are far from identical in appearance, to someone with little or no knowledge about tarantulas, they can appear similar to one another, especially as spiderlings.FINAL NOTES

In all fields of science, nothing is 100% exact, and taxonomy is good example of this [2]. Scientists often argue about the classification about species and whole genera are taken apart and reassembled based on new information all the time. Advances in genetic analysis allow us to take a closer look at the relationship between life forms, often with surprising results. Because we live in a world where things are constantly changing, where ranges of inhabitance overlap, and where interspecies breeding can occur, the field of taxonomy will probably continue to change indefinitely. In addition, even within a species differences in physiology can be seen. With a conscious effort to use correct nomenclature we can all remove a portion of the error, at least where science and hobby overlap.

[1] For more information on baboon spider taxonomy and descriptions, see www.BaboonSpiders.de

[2] For more information see Robson, G. C. (1928). The Species Problem: an Introduction to the Study of Evolutionary Divergence in Natural Populations. Edinburgh: Oliver and Boyd.

Poecilotheria in the Vivarium

Poecilotheria in the vivarium

By Kevin Scott

WARNING: The species of Poecilotheria described here are spiders that can be fast, aggressive and extremely dangerous to humans. They should NOT be handled.

VIVARIUM ORNAMENTS

Over the last decade or so there has been an explosion in vivarium popularity. Animals like arrow frogs, mantellas, day geckos and other small diurnal herps are a natural choice for such display cages because of their distinctive coloration and visibility during the day. Tarantulas and bird spiders have been largely neglected in this department, and not without reason. Most spiders are secretive, and will either bury themselves or spin thick, opaque webs, making it difficult to observe them. Either way this makes them difficult to be seen. In addition, most tarantulas will eat almost anything else that they are housed with.

fringed ornamental

The Fringed Ornamental Baboon Spider (Poecilotheria ornata)

Species of the genus Poecilotheria (Ornamental Baboon Spiders), however, can often be seen sprawled on pieces of wood or cork bark. While they cannot be housed with other animals (although they have been successfully kept communally), Poecilotheria species can make an unusual and decorative addition to the tropical vivarium.

CARE

Ornamental Baboon Spiders are from tropical South East Asia (India, Sri Lanka) and benefit from moderate to high humidity (50-75%), although they can go for extended dry periods if needed. Light daily misting is recommended if your vivarium is not humid enough from moss and/or plants that are established within it. As with humidity, heating situations can vary widely depending on the style and orientation of your vivarium, but a thermogradient with the warm side reaching temperatures of 78-80 degrees is recommended. Compact fluorescent lighting commonly used for vivaria usually emit sufficient heat for Ornamentals (although they normally shy away from bright light) but if this is not enough, an under-tank heater can be used as asecondary heat source.

vivarium

A simplistic arboreal vivarium with a hollow piece of grapewood is ideal for any of these species.

Again, each vivarium is different and care should be taken with tropical plants when selecting a spot for a heat source.

Being arboreal (tree-dwelling) animals, Poecilotheria species prefer vertically oriented vivaria. Adequate ventilation should be provided. Although they are often seen ‘out and about,’ hide spots are necessary. Cork hollows are ideal for this, and will allow your spider to build a web to retreat to, should it want to. Live plants with broad leaves, like pothos ivy, smaller philodendron and bromeliads, also provide excellent cover in this type of environment. A small water dish with a sponge or cotton balls should be offered, for your spider to stay hydrated.

indian ornamental

The Indian Ornamental (Poecilotheria regalis)

FEEDING

All Poecilotheria species can feed solely upon crickets. Spiderlings and adults alike can feed weekly, with the size of the food item ranging from small to large crickets, as is appropriate. Care should be taken to provide enough food if a communal vivarium is what you have in mind. Although Ornamentals have been successfully kept together (same species, same size only), they have also been known to cannibalize. If you set up a communal vivarium, it is essential that you provide enough food for your spiders. Several appropriately sized crickets should be fed to each spider weekly, with uneaten food items being removed from the cage with tweezers. Other food items including cockroaches, locusts, meal-, super-, and wax-worms can be fed as well, but in the vivarium these have a tendency to hide or dig if not captured immediately.

CLOSING COMMENTS

In closing, I would like to note that species of Poecilotheria are not the only spiders that do well in vivaria.Brachypelma species are another excellent addition to the tropical vivarium. These terrestrial counterparts are very hardy and less aggressive than the Ornamentals, and are readily available in the pet trade. Brightly colored and not as reclusive as some other tarantulas, these fascinating animals are a subtler main feature than brightly colored frogs or geckos, but if you take the time to set up and care for these eight-legged wonders I think that you will be pleasantly surprised.