The story behind Pandinus imperator

Pandinus imperator

Species name: Pandinus imperator (1841, C.L. Koch)

Common name: Emperor scorpion
Family: Scorpionidae
Distribution: Guinea, Liberia, Sierra Leone, Ivory Coast, Ghana, Benin, Togo, Nigeria
Habitat: Typically found in hot, humid tropical forests and savannas of West Africa.
Venom strength: Mild venom. Not dangerous to humans.

Temperament and behaviour
One of the largest scorpion species in the world, reaching lengths up to 20 cm (8-inches).
Although they are big and built like tanks, they can also be really sensitive.
Pandinus imperator is one of the most inoffensive scorpions found in the hobby. However, wild-caught specimens tend to be more aggressive than captive-bred specimens. This species will use its strong chelae for defence and capturing prey. The stinger is rarely used in defense and prey capture. Instead, emperors rely on their large and powerful chelae to hold and crush prey and discourage attacks from predators.

Defencive posture.

Pandinus imperator is a communal scorpion, easy to keep and maintain in groups. Sometimes a fight will break out between group members but lasts only a few minutes. However, emperors have been known to kill and eat cage mates. Fights usually break out when multiple scorpions in a group want to use the same common shelter. To avoid such problems always make sure that there is one shelter per specimen in group enclosures. I have seen at least 15 emperors of mixed instars (instar 5 to adult) making use of the same piece of shelter.

Sexing
It’s relatively easy to sex these animals.
First of all, males are more slender in build and generally a bit smaller than females. If only a single emperor is present, take a look at the pectines and the genital operculum. The pectines of a males are larger and have 14 to 17 teeth. The pectines of females will have 14 to 16 teeth. Because the pectine tooth count of males and females overlap in numbers, a pectine count won’t do any good for sexing purposes.
The most accurate method to determine sex is by looking at the genital opperculum; the operculum of the male is oval and that of the female more heart-shaped. Take a look at the pictures below to see the differences.

Male:

Female:

Breeding
At the moment I have one female that gave birth to 21 scorplings (30-April-2007). The female ate one scorpling that probably wouldn’t have survived on its own for long. The birth took a total of 3 hours.

On 17-May-2007 the scorplings molted to instar 2 (see picture above) and a few left the mothers back at 20-May-2007.

These scorpions are relatively easy to breed; make sure that the male and female are mature. Both of them must have been well fed. Courtship and mating can be initiated by the male or female. The promenade a deux or “dance” will include male juddering, pedipalp gripping, sexual stinging, cheliceral “kissing”, pectines of the male moving rapidly over the substrate surface, female swaying and last but not least, at the end of mating, females may attack, kill and consume the male (especially in wild-caught specimens). The male usually tries to make a get away, if the enclosure is large enough he will probably succeed.

The gestation period is relatively long and can take 9 to 11 months. Depending on environmental conditions. See the “housing” section for more details.

Pandinus imperator on average gives birth to about 11 scorplings, with a range from 1 to 20.
The scorplings are relatively easy to raise, the key is keeping them warm and humid. Always make sure that there is a water dish in the cage. I have raised Pandinus imperator scorplings in a group. The group consisted of 4 scorplings; I raised them in a large round deli-cup (diameter of 20 cm/8 inches). The substrate was coco peat, with to a depth of 10 cm (4-inches). I made ventilation holes in the top and sides of the cup in order to provide high ventilation to prevent the growth of molds and mite infestations.

These scorpions are slow growers; it can take up to 2 years (or even longer) before an emperor reaches adulthood. While in the wild there are specimens reported to reach adulthood within a year.
Mother emperors are known for taking good care for their young. They will crush food for them so they can have an easy meal. Even if you keep the scorplings with their mother for a longer period than typically recommended, there shouldn’t be any problems. Just make sure to keep them well fed.
I prefer to separate the young to make sure they are all healthy and getting enough food to grow.

Housing
These scorpions come from humid and warm tropical forests and savannas of western Africa, therefore, keep them in a humid (80 %) and warm (30 *C/86 *F during the day; 20 *C/ 68 *F during the night) environment. Keep one adult specimen in an enclosure of about 50x30x30 cm (20x12x12 inches). If housing an adult pair, the enclosure should be at least 60x40x30 cm (24x16x12 inches). Floor space is more important than height.

The substrate I use is coco peat because it can be easily moistened and retains humidity levels in the enclosure. If needed, you can always make use of the false bottom method (see below). Give these scorpions a moist layer of substrate at least 10 cm (4-inches) in depth. They love to dig and should be given the opportunity to do so in captivity. Another very important thing to place in their enclosure is a water dish; they like to drink a lot. Furthermore, in group enclosures, always provide 1 shelter per specimen. These scorpions do not like sunlight and other forms of bright light and should always be provided with retreats that will allow them to get away from bright lights. Shelters can be made out of wood or stones. Make sure the shelter is securely placed in a way that it cannot fall down upon the scorpion.

False bottom setup
This is a very handy method to make sure the humidity stays at the high end.
To start, fill the bottom of the enclosure with a good layer of gravel. Place a hollow tube on the gravel-layer and fill the enclosure with the desired substrate. Through the fill tube; add water to the gravel-layer. Make sure to fill until half the gravel-layer is submerged. The water will seep down and through the substrate, insuring that the substrate remains moist at all times. The only thing to take care of is to check the water level weekly and add more as necessary to keep it at the recommended level.

Feeding
Like all scorpions, emperors will eat almost anything they can capture, from crickets to lizards.
I’ve even seen them scavenging: taking a dead grasshopper from the substrate and simply eating it. Younger emperors can be fed crickets and mealworms, while the larger animals seem to like large grasshoppers more than crickets and other types of prey.

Feed younger animals a single prey item twice weekly. Larger animals and adults can be fed once every week. Adults may even refuse food for short periods of time.

Understanding Pandinus imperator
Sometimes I get a lot of questions about this species, I will hereby try to explain the most frequently asked questions. The questions I receive about housing, temperature and other related subjects will not be explained here, since these topics are covered under “housing” above.

Q: My P. imperator seems to be dragging its tail all over the place; he/she seems to have lost function in it. What could it be?
A: This could be caused by old age, as I have seen in a few of my older scorpions. Not long after this the scorpions died. However it also seems to be caused by a too dry of an environment, especially in younger scorpions. You can try placing your scorpion in a moister environment with a lower temperature for a day or two to see whether the scorpion returns to its normal behaviour.

Q: I have always heard that P. imperator is a calm scorpion; mine is always trying to attack me. Why is this?
A: There is a big difference between individual specimens and one scorpion won’t act like another. Furthermore, I have seen a big difference between wild-caught specimens and captive-bred specimens. The wild-caught specimens seem more aggressive compared to the captive-bred. If your scorpion is a female, it may be gravid? Gravid females tend to be more aggressive than non-gravid females.

Q: Do these scorpions climb? My emperor was in its enclosure but now it seems to be gone!
A: First of all, despite their large size and cumbersome weight, emperors are very good climbers. Don’t let their size fool you on that point. Secondly, these animals can lift themselves up by standing upright on their tails. Make sure that the lid of your enclosure can lock securely to prevent escapes. If your enclosure is properly sealed and locked, try searching in the substrate. It could have dug a new burrow or may have closed an existing burrow with substrate.

Q: I have an adult imperator, but I’ve not seen it eat for a few weeks now. The housing and environmental conditions are good. Is my scorpion sick?
A: Adult imperators (especially males) are known for not eating for a long time. Just keep the temperature and humidity at the levels recommended above and wait. Try to offer prey once per week and see if your scorpion feeds. If not, remove the prey and retry in another week. It can take awhile but eventually your emperor will start eating again.

References:
-   The scorpion files, Gary A. Polis and others.
-   Lucian K. Ross, paper about Pandinus imperator.
-   Raising Pandinus/Heterometrus Babies, www.venomlist.com by BrianS

- www.pandinus.net, by Dr. Boris F. Striffler

Thanks to:
- The people of venomlist.com for providing extra info on Pandinus imperator
- Lucian K. Ross for his outstanding paper about Pandinus imperator and for giving advice on writing the article.

- Dr. Boris F. Striffler for his advice on the distribution of Pandinus imperator.

- Rien Groeneweg, for providing a few pictures of the burrow.