Which group of organisms includes species that do not possess a backbone?

The correct answer is invertebrates, as this group specifically comprises organisms that lack a backbone or vertebral column. Invertebrates include a diverse range of species such as insects, mollusks, and crustaceans, which collectively account for a significant majority of animal life on Earth. Their anatomical structure allows them to thrive in various environments and contribute to ecosystem functions in unique ways.

Carnivores refer to organisms that primarily consume other animals, which can include both vertebrates and invertebrates. Producers are organisms that can create their own food through processes like photosynthesis, such as plants and some algae, but this classification does not address whether or not they have backbones. Autotrophs, like producers, are organisms that produce their own nutrients but include both plants and some microorganisms. Again, this classification is independent of whether they possess a backbone.

Focusing on invertebrates helps highlight their importance in ecological systems, as they play critical roles in food webs, nutrient cycling, and as indicators of environmental health.