Water Stripers

Gerridae. Spanish: Zapateros (Argentina). Pond skaters.

These are oval to elongate bugs with four-segmented antennae and large, globular eyes. Their other distinctive features are slender spiderlike legs, with tarsal claws inserted before the tip of the last segment. The body is covered with a velvety pile of hairs that are hygrophobic and make the insect resistant to wetting should it submerge. Their colors range from black to brown with occasional silvery markings. Wings may be absent, abbreviated, or fully developed.

Water striders (Andersen and Polhemus 1976) all are "semiaquatic bugs," spending their entire lives moving jerkily to and fro on the surface film. They feed on the blood of insects and invertebrates that fall onto the surface film or reside on it. A common species is Gerris remigis (fig. 8.5d).

One group of striders has colonized the open ocean. The best known of these, the "sea skaters," belong to the genera Halo-bates (Herring 1961, Cheng 1985) and Rheumatobates (Cheng and Lewin 1971), which generally resemble freshwater striders except for a grossly reduced abdomen and complete absence of wings. Just a few species live on the waters of the ocean off both coasts of America and among associated oceanic islands. Halobates micans (fig. 8.5e) and H. robustus are common inhabitants of small bays in the Galápagos Islands. Little is known of their biology. Coastal species lay their eggs on rocks; pelagic species may oviposit on floating objects (wood, feathers) and are even known to attach eggs to birds that have been resting on the waves. Their food consists of pelagic, surface-dwelling animals like jellyfish.

Refer to Bachmann (1977), Nieser (1981), and Polhemus (1982) for bibliographies on the regional fauna.

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