ZOL 353 Lecture Notes - Lecture 33: Tusk Shell, Lithophaga, Phoronid
Document Summary
Polychaetes, phylum annelida: highly diverse with many marine members. Distinctly segmented: each segment has a pair of parapodia, have setae (bristles, many have complex heads, some have eversible proboscis for seizing prey, some have feathery external gills, some have feathery, ciliated extensions for suspension feeding. Oligochaetes, phylum annelida: many species, some freshwater or terrestrial, no parapodia, small setae, small heads, marine species are typically deposit feeders, ingesting organic matter in sediment. Peanut worms: phylum sipuncula: about 300 species, all marine. An unusual deep-sea gastropod, the scaly-foot gastropod chrysomalion squamiferum: lives in indian ocean hydrothermal vents 2,400-2,800m deep, shell three-layered, with iron sulfide outer layer, middle layer as in other gastropods. Inner layer aragonite: sides of foot armored with iron and pyrite scales, use of iron sulfide is unique among animals to this genus, obtains nutrients solely from symbiotic bacteria in esophagus, huge heart, 4% of body volume.
