Water scorpions

Definition

Aquatic true bugs (family Nepidae) characterized by long, slender respiratory siphons extending from the abdomen tip, raptorial forelegs adapted for seizing prey, and a dorsoventrally flattened body. Despite the common name, they are not scorpions; the siphon resembles a scorpion's tail but lacks a stinger. They breathe atmospheric air through the siphon while submerged and are ambush predators in lentic and slow-flowing waters.

Etymology

From English 'water' (habitat) + 'scorpions' (resemblance of caudal siphon to scorpion tail)

Example

Ranatra fusca, the brown water scorpion, uses its needle-like siphon to pierce the water surface film while remaining fully submerged, waiting to strike at tadpoles or small fish with its grasping forelegs.

Synonyms

• Nepidae

Related Terms

• true bugs
• Hemiptera
• Nepa
• Ranatra
• respiratory siphon
• raptorial forelegs
• aquatic insects
• ambush predator

Usage Notes

Strictly refers to family Nepidae, not scorpions (order Scorpiones). The two genera most frequently encountered are Nepa (broad, oval body, short siphon) and Ranatra (elongate, stick-like body, very long siphon). The siphon is a respiratory structure, not a defensive weapon—confusion with scorpion morphology is a common lay misconception.