Egg laying by a female spider filmed by Alvaro Mendoza. Highly choreographed light use makes this short observation particularly striking.
Spiders reproduce sexually. Fertilization is internal but the sperm is not inserted into the female’s body by the male’s genitals. Unlike many land-living arthropods, male spiders do not produce ready-made spermatophores (packages of sperm). Males spin small sperm webs on to which they ejaculate and then transfer the sperm to syringe-like structures on the tips of their pedipalps.
Female spiders can lay up to 3,000 eggs in one or more silk egg sacs which maintain a constant humidity level. In some species the females die afterwards, but females of other species protect the sacs by attaching them to their webs, hiding them in nests, carrying them in the chelicerae or attaching them to the spinnerets and dragging them along.
The film beautifully shows the eggs coming out of the ovaries and their transition from larva into juvenile spiderlings. These individuals can often be seen in dense groups after they hatch. Some spiders provide parental care for their young. A wolf spider’s brood cling to rough bristles on the mother’s back and females of some species even respond to the “begging” behavior of their young by giving them a captured prey, or even regurgitate food.