| Heterobranchia | |
|---|---|
 | |
| Four examples of Heterobranchia | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Subclass: | Heterobranchia J.E. Gray, 1840 |
| Taxonomic subcategories | |
|
informal group Lower Heterobranchia | |
The Heterobranchs are a large group of snails and slugs. The group includes marine, aquatic and terrestrial gastropod molluscs.
Heterobranchia is one of the main clades of gastropods. It has three informal groups: The details are extremely complicated, and not yet quite worked out. Experts say they have "poorly resolved phylogenetic relationships".
- Lower Heterobranchia: a group of rather specialized, highly evolved sea slugs and sea snails.
- Opisthobranchia: almost all are marine species, some shelled and some not. They are a group of slugs and snails with grinding gizzard plates.
- Pulmonata. This is a group which is familiar to most people. It includes most land snails and slugs, many freshwater snails and a few marine species. They breathe air, are hermaphrodite, and usually have no operculum.