In: Biology
Which phyla are protostomes and which phyla are deuterostomes?
Protostomes: An animal in which the blastopore becomes the mouth
The coelomate protostomes include two lineages—one group includes echiurans, annelids, pogonophorans, onychophorans and arthropods which are characterised by segmentation and spiral cleavage, and another group which is non-segmented includes sipunculans and molluscs which have evolved from non-segmented ancestor.
The absence of segmentation in echiurans, sipunculans and molluscs is a secondary loss
Based on current molecular data, it has been suggested that the coelomate protostome animals can be divided into 2 groups:
1. Ecdysozoa, e.g., Arthropods and Nematodes (pseudocoelomates)
2. Lophotrochozoa, e.g., Molluscs and Annelids.
Deuterostomes: An animal in which the blastopore does not become the mouth
The deuterostomes include Echinodermata, Hemichordata, and Chordata.
The echinoderms, hemichordates, and chordates share some common features such as gill slits (absent in living echinoderms but are found in fossil carpoids), protocoelic nephridium (present in echinoderms and hemichordates but in chordates, it has secondarily lost).