flatbacked

Flatbacked is an adjective used in biology to describe organisms or objects that have a dorsally flattened back or a dorsal surface that is flat rather than arched. It is a descriptive term rather than a formal taxonomic rank, and it can apply to a range of organisms and occasionally to man-made items with a flat posterior surface.

In zoology, flatbacked forms occur in several lineages. The most widely cited example is the flatback sea turtle, Natator depressus, whose carapace is notably flattened relative to other sea turtles, a feature reflected in its common name. This morphology is thought to relate to its specific habitat and swimming style, though the trait itself remains descriptive.

In invertebrates, flat-backed forms are noted in various groups. For example, many millipedes in the order Polydesmida are commonly described as flat-backed, with dorsoventrally flattened bodies adapted to life in leaf litter and under bark. Some isopods also display a flattened dorsum, aiding concealment and movement in tight spaces.

Outside of biology, flatbacked is sometimes used to describe man-made objects with flat backs, such as certain shells or hardware components, indicating a flat dorsal surface for assembly or aesthetics. The term emphasizes form and morphology rather than a specific lineage, and its usage can vary by field and context.