Novel cadmium-inducible peptides were purified from the barnacle, Megabalanus volcano. They lacked cysteine and contained high amounts of acidic residues. Their molecular weights were much smaller than those of other cadmium-inducible/binding proteins. These peptides, megabalanein A (CdIP1) and megabalanein B (CdIP2) may be the smallest metal-inducible peptides that have been found in vertebrates and invertebrates.