Arthropoda - "Jointed Legs"
When male and female crabs reproduce, they position themselves in which the male carries the female. Mating can last up to about five hours, but the crabs can stay in the same position for up to three days. After the male transfers the sperm, she stores the sperm on the underside of her abdomen, where she will be use it for two more times of spawning that occur within her three-year lifespan. The females migrate to saltier waters after mating and attach between 100,000 to two million eggs to the sperm stored under the abdomen. The incubation period lasts about two weeks, until the larvae hatch and released into the ocean to fend for themselves.
Centipede reproduction begins when the male produces a small amount of sperm. Some centipede males perform a courtship ritual to attract the females. In other species, males simply set the mass down for the female to find. The female centipede takes the sperm and will then use it to fertilizes the eggs. Female centipedes deposit the eggs into the soil. The stone centipedes deposit their eggs in holes and cover them up. House centipedes also deposit their eggs in holes and cover them up.
The spider, like every other animal has a very difficult time trying to find a female to reproduce with. Since Spiders usually live solitary, it can be challenging to find a female in your area before another male gets there first. Both the male and female reproductive organs are at the rear of the abdomen, but spiders don't mate by coupling these organs. Instead, the male deposits some sperm onto a small web and picks it up on the end of his pedipalps. When the female is in position, the male deposits the sperm in the female's genital opening. The female stores the sperm in receptacles near the ovaries. When she is ready to lay her eggs, months down the road in some species, she uses the sperm to fertilize them. Some spiders may lay hundreds, even thousands of eggs in one shot.
Reproduction in Scorpions start off when a male and female scorpion successfully find a mate through courtship dances and other rituals. Once they have a mate, the male will find a suitable place for him to release his sperm. He will then lead the female over to the sperm so that it can enter through her genital opercula. This process triggers the sperm which fertilizes the female. This mating process can last up to a day depending on the location of the sperm.