Insects that are Surprisingly Not Insects

Insects that are Surprisingly Not Insects


Taxonomy is the scientific identification and classification of organisms through the use of hierarchical categories. All known creatures both alive and extinct have undergone taxonomic classification, from being members of a broad category, all the way down to their specific species. There are 8 taxonomic categories starting with the largest umbrella categories and becoming more specified with each following level. Each division is created based on a series of similarities or dissimilarities between creatures. In descending order, the categories are arranged as such: Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.

Due to this very detailed organization based on similar characteristics, some creatures that we consider insects or bugs are actually not technically insects or bugs at all. This taxonomical tree is the basis that will help explain how the following six creatures are not what you originally thought.


Worms, like every creature on this list are part of the kingdom Animalia. However, uniquely they are part of a phylum called Annelida. This phylum consists of over 22,000 species of bilaterally symmetrical ringed and segmented worms including: earthworms, leeches, ragworms, etc. This phylum completely separates worms from bugs, insects, and arachnids.

Roly Polys/Pill Bugs

Roly polys are part of the Arthropoda phylum, making them related to insects and arachnids, however, they are part of a different class altogether. They are members of the subphylum Crustacea, which range in size from microscopic plankton to the 4.3 m giant crab. Crustaceans include crabs, lobsters, krill, shrimp and, of course, roly polys.  Due to the extensive diverse nature of this subphylum, it is broken up into five different classes: Branchiopoda, Ostracoda, Remipedia, Maxillopoda, and Malacostraca. Roly polys are part of the largest of these classes, the Malacostracans which includes marine, freshwater and terrestrial invertebrates.

Spiders and Ticks

Often times, spiders and ticks are referred to or even believed to be insects, however, they are not part of the class Insecta. Rather, they belong to a separated class in the Arthropoda phylum called Arachnida. Arachnids have eight legs, simple eyes (instead of compound eyes), lack antennas and wings, and have segmented bodies broken down into two parts (unlike the three in insects). There are over 100,000 different species of arachnids including spiders, ticks, scorpions and mites to name a few.

Centipedes and Millipedes

Like roly polys, centipedes and millipedes belong to a subphylum of Arthropoda called Myriapoda. This subphylum consists of over 13,000 different terrestrial species. The name myriapoda is of Latin origin and means “having many legs.” These creatures have segmented body parts with between 10 to 750 legs depending on the specific species.


Bousfield, E. and Conlan, K. (no date) Malacostracan – CrustaceanEncyclopedia Britannica. Available at: (Accessed: November 2020).

The Difference Between an Insect and an Arachnid (2020) Allan’s Pet Center. Available at: (Accessed: October 2020).

Earthworm – Annelid (no date) Encyclopedia Brittanica. Available at: (Accessed: November 2020).

Phylum Arthropoda, Subphylum Crustacea (no date) Key to Australian Freshwater and Terrestrial Invertebrates. Available at: (Accessed: November 2020).

Taxonomy (2020) Basic Biology. Available at: (Accessed: November 2020).

Towne, J. (2019) Are Insects Animals?Medium. Available at: (Accessed: November 2020).