Deuterostomes differ from protostomes in several ways. Animals from both groups possess a complete digestive tract. However, in protostomes, the first opening of the gut to appear in embryological development (the archenteron) develops into the mouth, with the anus forming secondarily. In deuterostomes the anus forms first, with the mouth developing secondarily. In most protostomes, cells simply fill in the interior of the gastrula to form the mesoderm, called schizocoelous development, but in deuterostomes, it forms through invagination of the endoderm, called enterocoelic pouching. Deuterostome embryos undergo radial cleavage during cell division, while protostomes undergo spiral cleavage. COUNT 5
QSN1 What do deuterostomes and protostomes have in common? ANS1 both groups possess a complete digestive tract QSN2 In which group does the anus form first, with the mouth developing secondarily? ANS2 deuterostomes QSN3 What is the process in which cells fill in the interior of the gastrula to form the mesoderm called? ANS3 schizocoelous development QSN4 What is the process in which the mesoderm is formed through invagination of the endoderm called? ANS4 enterocoelic pouching QSN5 What do deuterostome embryos undergo during cell division? ANS5 radial cleavage