Which small arthropod has eight legs and no antennae?

The correct answer is the mite. Mites are small arachnids classified under the class Arachnida, which means they have eight legs, characteristic of arachnids, and they typically do not possess antennae. This distinguishes them from various other arthropods like insects, which do have antennae.

Mites play significant roles in different ecosystems, including both beneficial functions such as decomposition and soil aeration, as well as being known pests for plants and animals. Their small size can make them hard to spot, and there are many species, some of which can cause damage to crops in turf and ornamental settings.

In contrast, spiders and ticks are also arachnids with eight legs, but spiders possess distinct features such as multiple body segments and fangs, while ticks are more recognizable for their blood-feeding behavior and often larger size. Scorpions, while also part of the arachnid family, are known for their pincers and segmented tails, making them easily identifiable. Each of these alternatives has unique morphological traits, but the defining characteristic of lacking antennae and being part of a broader group of arachnids makes the mite the most fitting answer to this question.