Fusiform

Definition

Tapering toward both ends from a central swelling; spindle-shaped. In arthropod morphology, describes body regions, eggs, cocoons, or other structures that are widest at the middle and narrow progressively toward anterior and posterior poles. Distinguished from ellipsoid (uniformly curved) and lemon-shaped (bluntly rounded ends with a single broadest point).

Etymology

From Latin fusus (spindle) + -form (shaped like)

Example

The fusiform eggs of many praying mantids (Mantodea) are laid in hardened oothecae, with the tapered ends oriented to fit efficiently within the frothy matrix; similarly, the abdomen of some adult dragonflies appears fusiform when at rest, though it broadens during respiratory pumping.

Synonyms

• spindle-shaped

Related Terms

• ellipsoid
• cylindrical
• Lanceolate
• Clavate
• ovoid
• tapered

Usage Notes

Specialists use fusiform with precision: the tapering must be gradual and bilateral, not abrupt or unilateral. Contrast with 'clavate' (club-shaped, swollen at one end only) and 'lanceolate' (lance-head shaped, typically widest below midpoint and tapering to a point). In insect eggs, fusiform shape often correlates with insertion into plant tissue or soil, where streamlined ends reduce mechanical resistance.