heterobranch
Heterobranchia is a major clade within the class Gastropoda, encompassing a highly diverse collection of snails and slugs that inhabit marine, freshwater, and terrestrial environments. The group includes many lineages formerly treated as separate orders, such as the opisthobranchs (sea slugs, sea hares, bubble snails) and the pulmonates (land and freshwater snails and slugs). Molecular phylogenetics supports Heterobranchia as a monophyletic lineage, though the internal relationships among its subgroups are still refined. The name derives from Greek roots meaning “different gills,” reflecting historical variation in gill arrangement among its members.
A characteristic feature of heterobranchs is their tendency toward anatomical reorganization compared with other gastropods, including
Diversity and examples: heterobranchs include well-known forms such as nudibranchs (colorful sea slugs), sea hares, and