What is the name of the second pair of appendages found on arachnids, used for sensory reception?

The second pair of appendages found on arachnids, which are primarily used for sensory reception, are called pedipalps. These structures are significant because they aid in various functions such as feeling, tasting, and mating. Unlike the walking legs, which are primarily used for locomotion, pedipalps serve a more specialized role in handling prey and sensory perception within the arachnid's environment. They can also be dimensional in sexual dimorphism; in males, pedipalps are often adapted to transfer sperm to the female during mating, highlighting their important role in reproductive strategies.

The other options are not correct due to their specific functions: walking legs are used for movement, swimmerets are primarily found in crustaceans for swimming, and antennules are sensory appendages found in some aquatic organisms, not arachnids.