Cimoidea

The Cimoidea is a superfamily of sea snails, marine gastropod mollusks in the clade Littorinimorpha. These snails are primarily known for their heterostrophic protoconch (larval shell) and their mostly planktotrophic larval stage.

Characteristics:

Cimoidea are characterized by a number of features, including:

• Heterostrophic Protoconch: The protoconch, or larval shell, is coiled in a different direction from the later whorls of the adult shell. This is a key diagnostic feature of the group.

• Planktotrophic Larvae: Most Cimoidea have planktotrophic larvae, meaning the larvae feed on plankton in the water column during their development.

• Shell Morphology: Adult shells are typically small to medium-sized, and vary in shape depending on the specific family and species.

• Habitat: Cimoidea are found in a variety of marine habitats, ranging from shallow intertidal zones to deeper waters.

Taxonomy:

The taxonomy of the Cimoidea has been revised several times. Traditionally, it included families now classified elsewhere. The precise composition of the superfamily and its constituent families can vary depending on the source and ongoing phylogenetic research. Some families historically associated with the Cimoidea include:

• Mathildidae (now often placed in Architectonicoidea or a separate superfamily)
• Triphoridae (now in Triphoroidea)

It is essential to consult current taxonomic databases and scientific literature for the most up-to-date classification of families within the Cimoidea.

Significance:

Cimoidea contribute to the biodiversity of marine ecosystems and play a role in marine food webs. Studying their larval development and shell morphology provides insights into gastropod evolution and biogeography. Their heterostrophic protoconch is particularly significant for understanding evolutionary relationships within the Heterobranchia.