Which statement is correct about protostomes?

Which statement is correct about protostomes?

• A. They are usually schizocoelomates
• B. They are usually enterocoelomates
• C. They lack a coelom
• D. They form a coelom by out-pocketing of gut

Answer: (A)

Protostomes mainly differ from other animals by how their body cavity forms during development. In most protostomes, the coelom arises when solid blocks of mesoderm split open to create the cavity—this is schizocoely. That pattern is what the phrase “schizocoelomates” captures, so it’s the best description for how protostomes typically develop their coelom. By contrast, forming the coelom by out-pocketing of the gut is enterocoely, a feature more associated with deuterostomes. So saying protostomes form a coelom this way doesn’t fit the usual pattern. And while some protostomes can lack a true coelom or have a pseudocoelom, that isn’t the general rule for the group.

Protostomes mainly differ from other animals by how their body cavity forms during development. In most protostomes, the coelom arises when solid blocks of mesoderm split open to create the cavity—this is schizocoely. That pattern is what the phrase “schizocoelomates” captures, so it’s the best description for how protostomes typically develop their coelom.

By contrast, forming the coelom by out-pocketing of the gut is enterocoely, a feature more associated with deuterostomes. So saying protostomes form a coelom this way doesn’t fit the usual pattern. And while some protostomes can lack a true coelom or have a pseudocoelom, that isn’t the general rule for the group.