Which of the following groupings includes the largest number of species? (Explain your answer.)
a. Invertebrates
b. Arthropods
c. Insects
d. Vertebrates

Verified step by step guidance

1. Understand the hierarchy of biological classification: In this question, the groups listed (invertebrates, arthropods, insects, vertebrates) are not taxonomic ranks but rather descriptive categories of organisms. The goal is to determine which group encompasses the largest number of species.
2. Define each term: - Invertebrates: Animals without a backbone, which include a wide variety of phyla such as arthropods, mollusks, annelids, cnidarians, and more. - Arthropods: A phylum within invertebrates that includes insects, arachnids, crustaceans, and myriapods. - Insects: A class within arthropods, characterized by three body segments, six legs, and often wings. - Vertebrates: Animals with a backbone, which include fish, amphibians, reptiles, birds, and mammals.
3. Compare the inclusiveness of each group: - Invertebrates are the most inclusive group because they encompass all animals without a backbone, including arthropods, mollusks, and others. - Arthropods are a subset of invertebrates, so they include fewer species than invertebrates. - Insects are a subset of arthropods, so they include fewer species than arthropods. - Vertebrates are a completely separate group from invertebrates and include far fewer species than invertebrates.
4. Analyze the relationships: Since invertebrates include arthropods, and arthropods include insects, the group 'invertebrates' must have the largest number of species overall. Vertebrates, being a separate and smaller group, cannot surpass invertebrates in species count.
5. Conclude: The group that includes the largest number of species is 'invertebrates' because it is the most inclusive category, encompassing a vast diversity of animal phyla, including arthropods and insects.

Key Concepts

Biodiversity

Biodiversity refers to the variety of life forms within a given ecosystem, biome, or on the entire planet. It encompasses the diversity of species, genetic variations, and ecological complexes. Understanding biodiversity is crucial for recognizing the vast number of species that exist and their roles in ecosystems.

Arthropods

Arthropods are a phylum of invertebrate animals characterized by their exoskeleton, segmented bodies, and jointed appendages. This group includes insects, arachnids, crustaceans, and more, making it the largest phylum in the animal kingdom. Their immense diversity contributes significantly to global species counts.

Insects

Insects are a class within the phylum Arthropoda and are the most diverse group of animals on Earth, with millions of described species. They play vital roles in ecosystems as pollinators, decomposers, and as part of the food web. Their sheer number and variety make them a key focus in studies of biodiversity.