Water boatmen are common aquatic insects often observed gliding through freshwater environments. They possess unique characteristics and behaviors that allow them to thrive underwater. This article explores their defining traits, appearance, aquatic life, and how they differ from other water insects.
Defining the Water Boatman
Water boatmen are true bugs belonging to the family Corixidae within the order Hemiptera. Over 500 species are known globally, with about 125 to 132 found in North America. Unlike most other true bugs, water boatmen are largely non-predatory. They are found worldwide in diverse freshwater habitats. Their name originates from their flattened, boat-like body shape, well-suited for their aquatic lifestyle.
Appearance and Identification
Water boatmen typically have a slender, oval, and streamlined body, ranging from 3 to 16 millimeters in length. Their bodies are often dull-colored, appearing brownish-green, gray, or dark brown, and frequently feature fine, dark, parallel crosslines on their flattened backs. Their head is broad with large, prominent eyes and a short, conical rostrum.
Their leg structures are distinctive and adapted for aquatic movements. They possess short, scoop-shaped front legs for gathering food. Their long, oar-like hind legs are covered with fine hairs, acting as paddles to propel them through the water. The middle legs are slender and assist in clinging to submerged objects.
Habitat and Behavior
Water boatmen are commonly found in still or slow-moving freshwater bodies, often preferring areas with abundant aquatic vegetation. They navigate the water using their powerful hind legs in a rowing motion, typically swimming right-side up. When not actively swimming, they may cling to plants or rest on the bottom.
Lacking gills, water boatmen breathe by carrying a thin, silvery bubble of air trapped under their wings and around their body, functioning like a diving bell. They periodically surface to replenish this air supply. Water boatmen undergo incomplete metamorphosis, progressing from eggs to nymphs that resemble miniature adults before molting into their adult form. Adult water boatmen are strong fliers and can move between water bodies, often attracted to artificial lights at night.
Diet and Ecological Role
Water boatmen primarily function as detritivores and herbivores within their ecosystems. They consume a diet mainly consisting of algae, decaying plant matter, and various microorganisms. Their mouthparts are adapted to suck juices from plants and algae. Certain species may also feed on small aquatic creatures like mosquito larvae, helping to control their populations.
Water boatmen play a significant role in aquatic food webs. They serve as a food source for a variety of aquatic animals, including fish, amphibians, birds, and larger invertebrates like dragonflies. By consuming algae and detritus, they contribute to nutrient cycling, transforming plant matter into animal tissue and maintaining ecological balance in their habitats.
Water Boatman vs. Backswimmer
Water boatmen are frequently confused with backswimmers due to their similar appearance and shared habitats. While both belong to the order Hemiptera, they are from different families: Corixidae for water boatmen and Notonectidae for backswimmers. A primary distinction lies in their swimming position: water boatmen swim right-side up, while backswimmers swim upside down.
Their leg structures also differ significantly. Water boatmen use their short, scoop-like front legs for feeding, whereas backswimmers possess grasping front legs designed for catching prey. Their diets also contrast: water boatmen are typically herbivores and detritivores, feeding on plant material, while backswimmers are predatory, consuming other aquatic insects, tadpoles, and small fish. Water boatmen are harmless and do not bite people. In contrast, backswimmers can deliver a painful bite.