Tergites

Tergites are the dorsal sclerotized plates that form the exoskeleton of arthropod body segments. In most arthropods the body is segmented, and each segment bears a dorsal plate (the tergite) on the top, a ventral plate (the sternite) on the underside, and lateral elements called pleurites. The tergite typically represents the dorsal portion of a segment and is aligned with the underlying segmentation, though in many groups the plates may be fused or reduced.

In insects, the thoracic tergites encompass the dorsal plates known as the pronotum, mesonotum, and metanotum, while the abdominal tergites are numbered (often T1 to T8). Tergites may be elaborated with sutures, ridges, or other modifiers, and they provide attachment surfaces for muscles and, in some lineages, for wings or their bases. In crustaceans, tergites can be incorporated into larger dorsal shields or carapaces.

Developmentally, tergites arise from the ectoderm and become hardened through sclerotization of the cuticle as the animal molts and grows. Their configuration can influence the overall body plan, locomotive capabilities, and protection. Variability across arthropods is common: some groups show highly fused dorsal plates forming a continuous shield, while others retain clearly delineated, movable tergites.

Etymology-wise, the term derives from Latin tergum, meaning back. See also sternite and pleurite for related dorsal, ventral, and lateral components of the arthropod exoskeleton.