Scorpion feeding is a more interesting subject than it may seem at first glance. The list of what they eat is short, but how they obtain it and how long they can make do with it sums up the whole design of a predator living in the arid belt.
What is on the menu?
Scorpions are non-selective predators. Arthropods make up most of their diet: various insects, spiders, centipedes and occasionally members of their own species. Some large-bodied species have been reported to take small vertebrates, but this is exceptional. What matters is not the type of prey but its size and whether it can be caught at that moment.
Finding prey does not rely on sight. Scorpions' eyes detect changes in light intensity; the main senses that let them find their way in the dark are vibrations in the ground and the slightest movements of the air. Slit-shaped receptors at the tips of the legs detect ground vibrations, while long sensory hairs on the pedipalps detect air currents. The structural details of this equipment were covered in the article on body structure.
This sensory equipment spares the animal from having to come out during the day. In a hot, arid region, moving about in daylight means both water loss and exposure to predators; a predator that can hunt by vibration in the dark avoids both costs. It is therefore no coincidence that hunting activity is concentrated at night.
Hunting is mostly done by ambush. The animal waits motionless at the entrance to its shelter and seizes prey with its pincers when it comes close. The sting is not used automatically: small, weak prey is simply held and processed with the pincers, while the sting comes into play against large or struggling prey. Because producing venom is costly for the animal, it is not wasted.
Digestion begins outside the body
Scorpions do not swallow solid food. As the captured prey is torn apart by the chelicerae at the mouth, digestive fluid is released onto it and the tissue begins to dissolve. The animal sucks up only the resulting liquid, and the hard parts left behind are not swallowed. The narrow space in front of the mouth works like a sieve, keeping large particles out.
A meal therefore takes a long time; the process can go on for hours. When it is over, the container holds a prey husk that looks intact from the outside but has been emptied. Spotting this remnant during husbandry is the most practical sign that the animal has actually fed.
Digestion that begins outside the body has another practical consequence: the animal can also process prey that is large relative to its own size. If it were limited by its swallowing capacity, the prey it could take would be much smaller. Liquid feeding lets the animal make full use of every opportunity in an environment where prey is hard to find.
The ingested liquid is processed in a large secretory and storage organ connected to the midgut. This organ both produces digestive enzymes and stores surplus energy as fat. This reserve plays a direct role in scorpions' ability to survive long periods of starvation.
Why can they go without food for months?
Scorpions use very little energy compared with many arthropods of similar size. Several reasons combine to explain this.
- Low resting metabolism: Energy consumption during long hours of inactivity is exceptionally low.
- Efficient respiration: Book lungs maintain gas exchange at low activity levels with little water loss.
- Body temperature set by the environment: No food is spent on keeping warm; in cooler periods, metabolism slows down by itself.
- Storage capacity: Surplus intake from times of plenty is stored as fat.
- Sit-and-wait hunting: Lying in ambush instead of roaming in search of prey eliminates the energy cost of searching.
Taken together, these features mean that many species can survive periods of starvation lasting months; laboratory observations have reportedly recorded periods of up to a year. The duration varies greatly with species, the individual's condition and environmental conditions, so it would be wrong to give a single figure. Access to water has a separate place in this picture; the subject is covered in the article on water requirements.
Feeding regime in the colony
In a closed facility, feeding becomes a recorded schedule rather than an imitation of the irregularity of nature. The aim is not to keep the animal constantly full but to ensure steady development and good health.
| Subject | In practice |
|---|---|
| Prey source | Insects reared under controlled conditions are preferred; prey collected outdoors carries a risk of residues and parasites |
| Prey size | Chosen so as not to overwhelm the animal; large, aggressive prey can cause injury |
| Timing | Feeding is postponed during moulting and for females carrying young |
| Leftovers | Uneaten prey is removed from the container; if left, it compromises hygiene |
| Records | The date and observations are recorded; a drop in appetite is often the first warning sign |
Another purpose of the feeding regime is to reduce aggression between conspecifics. This behaviour increases in groups that are underfed or kept too crowded; housing principles are described in the article on closed-cycle breeding. It is also established practice not to offer prey after a moult until the new exoskeleton has hardened; the stages of the process are covered in the article on moulting.
Feeding also affects the material itself. Venom composition is known to shift with the individual's condition, the season and its feeding history; this is one of the causes of the natural variability seen between batches. That is why measurements are repeated for every batch and the results are reported as batch-specific. Keeping feeding records in the colony logbook is the simplest way to be able to answer a question that may come up later.
