DNA, RNA, Ribosomal, 28S - genetics, Ribosomal - genetics, Ribosomal - chemistry, Ribosomal Spacer - genetics, 18S - genetics, Helminth - chemistry, Cetacea - parasitology, Trematoda - classification, Helminth - genetics, Trematoda - isolation & purification, Trematoda - genetics, Ribosomal Spacer - chemistry