The lesser water boatman is a master of aquatic navigation and liquid digestion

Nature · Published 3 October 2026 Swipe more like this →

In short: Commonly found in ponds and slow-moving rivers, the Corixidae family of insects are expert swimmers that navigate right-side up. These aquatic creatures, known as lesser water boatmen, possess specialized oar-like legs and a unique method of feeding that involves liquefying their prey before consumption through straw-like mouthparts.

The Corixidae family encompasses approximately 500 species distributed across 55 genera. These insects are characterized by flattened bodies measuring between 2.5 and 15 millimeters. Their physical structure is highly adapted for an aquatic lifestyle, featuring four rear legs equipped with oar-shaped tarsi and two shorter front legs covered in hair. Unlike their relatives, the Notonectidae or greater water boatmen, which swim inverted, Corixidae maintain an upright orientation while navigating freshwater habitats.

Feeding strategies among these insects are remarkably diverse. While many species forage in the benthic zone for algae, protozoa, and small organisms like brine shrimp, others exhibit specialized behaviors. Members of the subfamily Cymatiainae, for instance, are strictly carnivorous. To feed, they utilize triangular mouthparts to inject digestive enzymes into their food source, effectively turning the material into a liquid that can be ingested. This process allows them to exploit various food sources ranging from detritus to living larvae.

The life cycle of these insects is tied to the seasons, with an annual reproductive period. Females deposit eggs on diverse underwater surfaces, including rocks, vegetation, and occasionally even on the shells of crayfish. These eggs typically hatch within a fortnight. As adults, they demonstrate impressive resilience, capable of surviving beneath ice during winter months. Furthermore, many species engage in dispersal flights, reaching altitudes of up to 5,000 feet, and utilize complex stridulation to communicate and attract potential mates.

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