BLG 144 Lecture Notes - Lecture 33: Lophophore, Hydrostatic Skeleton, Trochophore
29 Sep 2017
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Document Summary
Protostomes are a monophyletic group, which means the protostome developmental sequence arose just once. The group"s name was inspired by the morphological traits that are found in some, but not all, of the phyla in the lineage: a feeding structure called a lophophore, a type of larva called a trochophore. A lophophore is a specialized structure that rings the mouth and functions in suspension feeding. A trochophore larva has a ring of cilia around its middle. These cilia allow swimming and, in some species, sweep food particles into the mouth. Neither lophophores nor trochophores qualify as a synapomorphy in lophotrochozoa. All ecdysozoans grow by moulting by shedding an exoskeleton or external covering. All protostomes are bilaterally symmetric, and all protostomes undergo embryonic development in a similar way. The coelom is absent in flatworms, and in most species-rich and morphologically complex protostome phyla. Arthropods have segmented bodies that are organized into prominent regions called tagmata.
