Bottger, A. ., Doxey, A. ., Hess, M. ., Pfaller, K. ., Salvenmoser, W. ., Deutzmann, R. ., Geissner, A. ., Pauly, B. ., Altstatter, J. ., Munder, S. ., Heim, A. ., Gabius, H. ., McConkey, B. ., & David, C. . (2012). Horizontal gene transfer contributed to the evolution of extracellular surface structures, the freshwater polyp Hydra is covered by a complex fibrous cuticle containing glycosaminoglycans and proteins of the PPOD and SWT (sweet tooth) families. PLoS One,7:E52278.