Scaphopoda

Scaphopoda are marine molluscs specialized for an infaunal lifestyle, defined by their tusk-shaped, tubular shell open at both ends. The body lacks a discrete head and eyes, and the elongate mantle cavity channels water from the posterior opening toward the anterior. A conical, muscular foot anchors the animal vertically within soft sediment.

The clade is uniquely characterized by captacula, numerous slender, contractile filaments used to capture small benthic prey, especially foraminifera, which are then processed with a radula. This feeding system has no analogue in other molluscan groups and is the most diagnostic feature of scaphopods.

Scaphopods have a fossil record extending to the early Paleozoic, dominated by isolated shells. Fossil and extant forms show little change in overall morphology, indicating long-term stability of the scaphopod body plan and ecology.