What term describes the specialized head structures of spiders used for grasping prey?

The specialized head structures of spiders that are used for grasping prey are called chelicerae. These are a pair of appendages located near the mouth and are adapted to help spiders capture and immobilize their prey. Chelicerae are often equipped with fangs that can inject venom, allowing spiders to subdue their prey efficiently. This ability is crucial for their feeding strategy, as many spiders rely on immobilizing their prey before consuming it.

In the context of other options, spinnerets are structures used by spiders to produce silk, primarily for web building. Mandibles are jaw-like structures found in other arthropods, such as insects, used for chewing, but they are not a feature of spiders. Pedipalps, although also appendages responsible for various functions including sensory perception and mating, are not specifically adapted for grasping prey like the chelicerae are. Therefore, the term that accurately describes the prey-grasping structures in spiders is indeed chelicerae.