Antenna

Definition

A paired, segmented, sensory appendage on the head of insects and other arthropods, primarily involved in detecting chemical signals (olfaction), mechanical stimuli (touch), and—in some groups—sound or humidity. Antennae vary enormously in form and are taxonomically diagnostic: filiform (thread-like, e.g., many beetles), setaceous (bristle-like, e.g., cockroaches), moniliform (bead-like, e.g., some beetles), serrate (saw-edged, e.g., click beetles), pectinate (comb-like, e.g., male sawflies), clavate (clubbed, e.g., butterflies), lamellate (plate-like, e.g., scarab beetles), geniculate (elbowed, e.g., ants), and plumose (feathery, e.g., male mosquitoes).

Etymology

From Latin antenna, originally a sail yard (the term was applied to insect appendages by analogy to their projecting form).

Example

The lamellate antennae of a June beetle (Phyllophaga) can fold its terminal plates together to detect pheromone concentrations, while the plumose antennae of a male mosquito amplify its capacity to locate females by sound.

Synonyms

• feelers (informal)

Related Terms

• Arista
• Johnston's organ
• Flagellum
• scape
• Pedicel
• Sensillum
• olfaction
• Pheromone
• Filiform
• Clavate
• geniculate

Usage Notes

Specialists reserve 'antenna' strictly for arthropod structures; vertebrate homologs do not exist. The term is sometimes misapplied to tentacles or palps—true antennae are always cephalic, paired, and primitively segmented. Crustaceans bear two pairs (antennules and antennae), while insects and myriapods have one pair; arachnids lack antennae entirely, a key distinction from insects. Form descriptors (filiform, clavate, etc.) are standard in keys and taxonomic descriptions.