Blue ring octopuss

Phasianus colchicus

Ring species complicate classification because they show a gradual change in characteristics among neighboring populations that can lead to challenges in defining clear species boundaries. The continuous variation in traits can make it difficult to determine where one species ends and another begins, blurring traditional classification criteria. This phenomenon highlights the complexity of species concepts and the limitations of traditional classification systems.

Any octopus, as a species, do not have a spine, so all are invertebrates.

The ring-tailed lemur is listed as Near Threatened by the IUCN, although it was originally listed as Vulnerable in 1990.