Facts about scorpions

Scorpion facts

After mating, the smaller scorpion, normally the male, is often in danger of being eaten.

The male and female find each other through pheromones, using their pectines. The male usually makes the first move, although some females do so. He usually has a complex courtship display to ensure the female knows he is one of her kind and not lunch. Some males “judder” (rapid rocking, shaking movements) to advertise his species (Vejovoides, Nebo). Some sting the female, possibly with pheromones, sedatives or other species identificators. Others club the female with their tails. Some males (Hadogenes) have ridiculously longer tails than females, suggesting that the length is important more for mating than hunting.

Despite having six to twelve eyes – an obvious pair at the centre of the carapace and two to five smaller eyes on each side – scorpions do not have good eyesight. However, they can readily distinguish light from dark and appear to have excellent low light sensitivity, which helps them to both avoid harsh sunlight and to navigate by starlight or moonlight. They sense their way around using sensory hairs and slit organs on the legs, pedipalps and body that pick up vibrations and scents (mechanoreceptors and chemoreceptors). They also have special organs on the underside of the body called pectines, which pick up ground textures and scents.

Scorpions also fluoresce under ultraviolet light, which is a good way for scientists to find them in the field. The fluorescence is thought to serve as an ultraviolet sensitivity mechanism, perhaps allowing the scorpion to avoid damaging light levels.

The fluorescence is caused by an unidentified substance in a very thin layer in the cuticle of the scorpion called the hyaline layer. Newly molted scorpions do not fluoresce. As the new cuticle hardens, the fluorescent quality increases. This indicates that the fluorescent factor is either secreted by the scorpion shortly after molting or that the fluorescence is a by-product of the tanning process.

The hyaline layer of the cuticle is very tough stuff. It is often found in scorpion fossils. Even after hundreds of millions of years, while all the other layers of the cuticle have been lost, this hyaline layer remains embedded in fossil rocks. And yes, it still fluoresces.

The female gives birth to live young. She carries the pale young scorpions on her back for the first few days or weeks, until they are strong enough to become independent. The young then disperse to find food and shelter. Scorpions take a long time to reach maturity, moulting frequently (up to five or six times over two to six years) in order to grow, and may live for two to ten years. Some have been recorded as living up to 25 years.