Based on embryonic development, metazoans are divided into protostomes and deuterostomes. Protostomes are primitive invertebrates and deuterostomes include chordates and echinoderms. This dichotomy is helpful to understand the different relationships between groups of animals.
The main difference between protostome and deuterostome is that in protostomes blastopore develops as a mouth and in deuterostomes blastopore is formed at anal opening. Differences between protostome and deuterostome are given in table column below.
What is Protostomes?
During embryonic development, a mouth with invertebrate species forms before the snout forms. These animals also have a decidedly spherical break and the differentiation of the mesoderm gives them the appearance of a coelom.
Some Examples of protostomes include octopuses, squids, snails, centipedes, millipedes, spiders, beetles, flies, turtles, caterpillars, clams and oysters.
Thus, the main difference between protostome and deuterostome animals is the modification of the mouth or in the blastopore.
What is Deuterostomes?
Embryonic development in the deuterostome proceeds through radial cleavage. When the blastula is formed by embryonic rupture, the process of cell division occurs radially.
In this group of animals, the first cavity formed by the blastopore develops in the cortex of the organism. Also after the formation of the nostrils, the mouth of the corresponding organism is formed on the other side.
Difference Between Protostomes and Deuterostomes
|
Protostomes |
Deuterostomes |
| In protostomes, the blastopore develops into a mouth | In deuterostomes, the blastopores develop into an anal opening |
| It exhibits determinate cleavage | It exhibits indeterminate cleavage |
| The gut forms the anus by tunnelling itself into the embryo | The gut forms the mouth by tunnelling itself into the embryo |
| It comprises of a solid ventral cord | It comprises of a hollow nerve cord |
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