eurypterid ...

it is considered likely that the first animals on land were eurypterids (largest known arthropods - "jointed feet" and with "external skeletons". over 80% of animal species living today are arthropods). fossil evidence indicates that they emerged from swamps about 440 million years ago, approximately 200 million years before dinosaurs first appeared. some were as large as 2.3 meters (7 feet). plants had only made it to land a short while before, and hadn't evolved much beyond mosses and other simple plants. today's scorpions are direct descendants of the ancient eurypterids, and have a very similar anatomy.

the first person to make a serious attempt to study scorpion was aristotle. geographical distribution shows in many particulars a close and interesting correspondence with that of the mammals, including their entire absence from new zealand.

they are easily distinguished from the insects by the fact that they have eight legs like their cousin, the spiders. all scorpions are predators, in general have three sets of eyes, all possess venom, do glow in the dark when exposed to ultraviolet light. many can go without food for a long time, up to a year. they can eat a huge amount in one sitting and also have the lowest metabolic rates among "cold blooded" creatures. many can go without water indefinitely.

scorpion mating is a dance, dangerous for both parties. most scorpions are loners because of their cannibalistic tendencies. when two scorpions meet, they usually fight until one is killed and eaten by the winner. after mating, the smaller scorpion is often in danger of being eaten. as females are usually bigger, it is the male which usually gets eaten.

scorpions don't lay eggs. the fertilised eggs develop into embryos in brood chambers within the mother's body. gestation is quite long, it can take several months to more than a year. the mother keeps her babies on her back for about a week. most mothers can recognise their own babies by smell and pick up fallen babies.

scorpions live 3-5 years on average, but some species can live for 10-25 years.

scorpions are threatened by habitat destruction. some have become popular pets and are endangered by over-collection for the pet trade. scorpions are vulnerable because they have the lowest rate of reproduction among arthropods.