Spiders are among the most abundant and important of all insect predators, whose numbers often exceed 100 per square meter, or one million spiders per hectare (10,000 m²). The ecological success of spiders has been attributed to key innovations in how spiders use silk to capture insects, mainly with different kinds of webs. Spider webs have diverse, intricate architecture resulting from complex adaptations that evolved under various selection pressures. Primitive orb-weavers of the Deinopoidea, for example, produce dry cribellar threads made of thousands of silks (cribellar threads are produced from the cribellum, a specialized, flattened spinning organ), while modern Araneoidea orb-weavers produce viscous adhesive threads with droplets. Both kinds of threads are very elastic and have among the greatest tensile strength of any substance in nature. The stickiness of adhesive thread is more effective, though, which may have contributed among other factors to the dominance in modern environments of araneoids with respect to the deinopoids.