Whirligig beetle  (Gyrinus substriatus)

Description

This small aquatic beetle is a metallic black colour with orange legs (4). They earn their common name from their habit of swimming in circles on the surface of the water, often very quickly (2). The name of this family of beetles, Gyrinidae, derives from the Latin for 'circle' (5). The middle and hind legs are modified for swimming; they are broad, flattened and oar-like, with a fringe of hairs (6). The compound eyes are unusual as they are divided into two, one pair is above the surface of the water, and one pair is below; this allows them to see above and below the waterline at the same time (3). The larvae have an elongated body shape, a narrow head and filamentous appendages on each segment (4).

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