Which term refers to animals without backbones, including insects, spiders, and earthworms?

The term that describes animals without backbones, such as insects, spiders, and earthworms, is "invertebrate." Invertebrates encompass a vast range of animal species and are characterized by the absence of a vertebral column or spine. This group makes up the majority of animal life on Earth, including various classes such as arthropods (which include insects and spiders) and mollusks (like snails and octopuses).

Understanding invertebrates is crucial for pesticide certification, as many invertebrates play essential roles in ecosystems, like pollination and pest control. Recognizing this category of animals is fundamental in distinguishing them from vertebrates, which have spinal columns.

The other terms, while related, refer to specific subsets or characteristics of animals. For instance, "arthropod" and "mollusk" are specific types of invertebrates but do not encompass the entire group. "Vertebrate," on the other hand, specifically refers to animals with backbones, making it an entirely different classification.