This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: commonly found as fossils. One genus, Turetella , occurs in such quantities in a type of rock that the rock is known as " Turetella agate". However, not all gastropods have shells, the nudibranchs (sea slugs) and terrestrial slugs lack shells. In aquatic gastropods, gills are found in the mantle cavity; in terrestrial gastropods, the mantle is richly supplied with blood vessels and functions as a lung when air is moved in and out through respiratory pores. Terrestrial gastropod embryonic development does not go through a swimming larval stage, as is the case in aquatic gastropods. For terrestrial snails, their shell not only offers protection but also prevents desiccation (drying out). The muscular foot contracts in peristaltic waves from anterior to posterior causing secretion of a lubricating mucus....
View Full Document
- Fall '10
- Biology, Gastropod shell, gastropods, Gastropoda, chitons