The Major Evolutionary Split of Protostome Animals was Into

Question

The major evolutionary split of protostome animals was into
A) diploblasts and triploblasts.
B) lophotrochozoans and ecdysozoans.
C) coelomates and acoelomates.
D) arthropods and molluscs.
E) segmented and nonsegmented animals.

Accepted Answer

The major evolutionary split of protostome animals was into lophotrochozoans and ecdysozoans, which are two major clades distinguished by different patterns of development and body structure. Diploblasts and triploblasts refer to the number of embryonic tissue layers, whereas coelomates and acoelomates refer to the presence or absence of a body cavity. Arthropods and molluscs are two major phyla within the protostomes, but they do not represent the major evolutionary split. Segmentation is a characteristic found in both protostomes and deuterostomes and is not a defining feature of either group.