Phylogeny

Of 34 major snake lineages 20 (59%) contain freshwater species,while only 8 (24%) contain species that have invaded brackish or marine waters. Again, supporting the idea that snakes do indeed have difficulty adapting to the physical environment of the oceans. Note that the natricids, homalopsids, and dipsadids have the largest number of species using coastal habitats. Codes in first column refer to major lineages (A) acrochordids (Bo) booids (C) colubroids (E) elapoids (H) homalopsids (L) lamprophids (P) pareatids (Py) pythonids (U) uropeltoids  (V) viperids (X) amerophids; (By) bolyeriids.