Rust-colored bearded (Erignathus barbatus) and ringed (Phoca hispida) seals from Svalbard, Norway

Bearded and ringed seals from Svalbard, Norway, often have strongly rust-co lored faces; the fore-flippers also are rust-colored in some animals. Eleme nt analyses of fur from normally colored and rust-colored seals of both spe cies showed that high concentrations of iron were present in the colored fu r indicating that iron oxides are probably the main reason for the unnatura l coloration, High concentrations of vanadium and manganese also were found in samples of colored fur. Oxides of these elements also may contribute to the discoloration. We suggest that seals acquire elements responsible for the coloration while feeding in soft-bottom sediments. Their faces and flip pers make contact with rich deposits of iron monosulfide in a reducing envi ronment. When this sediment is brought up into the water column by the seal s, the iron monosulfide is oxidized to form iron oxides that precipitate on to the hair shafts of the seals. The higher incidence of rust-colored beard ed seals, compared with ringed seals, is explained by the greater dependenc e of the former species on benthic prey items.