While unable to form sharp images, the central eyes of scorpions are amongst the most light sensitive in the animal kingdom, especially in dim light, which makes it possible for nocturnal species to use starlight to navigate at night.

Scorpions can also detect light through sensors in their tail.

Scorpion claws and tails are reinforced with iron and nickel.

Scorpion courtship involves a “dance” where the male and female grasp each other’s chelae (“pinchers”). This is called promenade à deux (French for "a walk for two"). In this dance, the male and female move around while facing each other, as the male searches for a suitable place to deposit his spermatophore. The courtship ritual can involve several other behaviors such as a cheliceral kiss, in which the male and female grasp each other's mouthparts, arbre droit ("upright tree") where the partners elevate their posteriors and rub their tails together, and sexual stinging, in which the male stings the female to calm her. The dance may take minutes to hours long. When the male has located a suitably stable surface, he deposits the spermatophore and guides the female over it. This allows the spermatophore to enter the female's genital opercula, which triggers release of the sperm, thus fertilizing the female.

All known species of scorpion give live birth, a rare trait among arachnids, and the female cares for the young as their exoskeletons harden, transporting them on her back for safety.

Like many other arachnids, scorpion exoskeletons contains fluorescent chemicals that glow under ultraviolet light, but scorpions are known for being especially vibrant (see gif above)

Hadrurus species dig burrows over 2 m (6 ft 7 in) deep.

While most scorpions are solitary, only coming together to mate, some species are more social. Species of the family Buthidae are often found in the same shelter and Bark Scorpions (genus Centruroides) may gather in groups of up to 30 individuals. In some species, families of females and her young sometimes live together even after the young have “weaned”.

Though scorpions prefer areas where the temperature remains in the range of 11–40 °C (52–104 °F), they may survive temperatures from well below freezing to desert heat. The Deathstalker (Leiurus quinquestriatus), Large-clawed Scorpion (Scorpio maurus), and Giant Desert Hairy Scorpion (Hadrurus arizonensis) can live in temperatures of 45 – 50 °C (113 – 122 °F) if they are sufficiently hydrated. Desert species must deal with the extreme changes in temperature from sunrise to sunset or between seasons: Pectinibuthus birulai lives in a temperature range of −30 – 50 °C (−22 – 122 °F).

Scorpions have immunity to ionizing radiation and have survived nuclear tests in Algeria and Nevada.

The immune system of scorpions is strong enough to resist several types of bacterial infections.

The vast majority of scorpion species are not a threat to humans, and healthy adults usually do not need medical treatment after a sting. People with allergies are especially at risk, but otherwise symptoms typically last no more than two days for non-deadly species. About 25 species (fewer than 1%) have venom capable of killing a human. Unfortunately, these species live where access to medical treatment is unlikely.

Venom takes a lot of energy to make, and is necessary for hunting, so scorpions will usually use it as a last resort defense. When threatened, they will raise their claws and tail in a defensive posture first. Some species stridulate to warn off predators by rubbing certain hairs, their stinger, or the pectines. Some species prefer to use their pinchers as their next line of defense before resorting to their sting, depending on the size of the appendages.

Scorpion venom is a mixture of neurotoxins. Many of them interfere with membrane channels that transport sodium, potassium, calcium, or chloride ions. These channels are essential for nerve conduction, muscle contraction and many other biological processes. Some of these molecules may be useful in medical research and might lead to the development of new disease treatments. Among their potential therapeutic uses are as analgesic, anti-cancer, antibacterial, antifungal, antiviral, antiparasitic, bradykinin-potentiating, and immunosuppressive drugs. As of 2020, no scorpion toxin-based drug is for sale, though chlorotoxin is being trialled for use against glioma, a brain cancer.

The pet trade has threatened wild populations of some scorpion species, particularly the Yellow Fat-tailed Scorpion (Androctonus australis) and the Emperor Scorpion (Pandinus imperator).