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Which larval features help scientists classify odonates?

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Male jewelwing damselfly (Calopteryx splendens). — Odonata Male jewelwing damselfly (*Calopteryx splendens*).

To classify larvae within the order Odonata, scientists examine several specific anatomical features that reflect the insects' adaptations to their aquatic environments. These key features include:12

Respiratory organs: The type and form of the gills are primary diagnostic tools. For instance, Zygoptera (damselflies) typically possess three external, leaflike plates at the tip of the abdomen, whereas Anisoptera (dragonflies) utilize internal gills located within the hindgut.12
Labial structure: Taxonomists analyze the structure of the labium, which includes the specialized, foldable "mask" used for capturing prey.32
Abdominal characteristics: The overall shape of the abdomen and the number and arrangement of body spines are significant for identification.12

These structural variations often correlate with the specific microhabitat a larva occupies, such as whether it is a burrower in sediment, a sprawler on the surface, or a climber among aquatic plants.13