Idotea balthica
Idotea balthica is a marine isopod which lives on seaweed and seagrass in the subtidal zone of rocky shores and sandy lagoons. Distribution. "Idotea balthica" has a broad geographical distribution, having been recorded from the Belgian Exclusive Economic Zone, The British Isles, Cobscook Bay, Dutch Exclusive Economic Zone, European waters, Greek Exclusive Economic Zone, Gulf of Maine, Knokke, North West Atlantic, Red Sea, Voordelta, West Coast of Norway, Wimereux and the Black Sea. Characteristics. The male is larger than female, and can reach long. The color of the body is extremely variable, ranging from muted greens to striking  black-and-silver patternings; the female is usually darker. The species can be distinguished from other idoteids by the shape of the telson, which is dorsally keeled with straight sides in "I. balthica", and has a distinct protrusion at the end. Foraging. Adults are potentially omnivorous, but mainly feed on different types of vegetation. In the Baltic, these include brown algae ("Fucus" spp., "Elachista fucicola, Pylaiella littoralis"), green algae ("Cladophora glomerata", "Ulva" spp.), and Phanerogams ("Stuckenia pectinata", "Ruppia" spp., "Zostera marina")"." In the Baltic, "I. balthica" prefers "Fucus vesiculosus", an algal seaweed, as host plant over other algae and vascular  plants. The apical and basal parts of "F. vesiculosus" differ as food and as shelter, and males grow faster when fed with the apical parts, but females grow equally well with both.