Question

In examining an unknown animal species during its embryonic development, how can you be sure what you are looking at exhibits protostome or deuterostome development?

O the animal's coelom develops from the archenteron.
O there is evidence of cephalization.
O the animal is triploblastic.
O the animal is clearly bilaterally symmetrical.

Answer 1

To differentiate protostome from deuterostome development in an embryonic animal, study the coelom formation method; protostomes show schizocoely and spiral cleavage, while deuterostomes show enterocoely, radial cleavage, and the blastopore becomes the anus.

Step-by-step explanation:

In determining whether an unknown animal species exhibits protostome or deuterostome development during embryogenesis, the key characteristic to observe is the method by which the animal's coelom develops from the archenteron. Protostomes typically undergo a process called schizocoely, where the coelom forms by the splitting of the mesodermal mass. In contrast, deuterostomes exhibit enterocoely, where the coelom forms from pouches off the endodermal tissue. These pouches, known as coelomic pouches, fuse and expand to fill the space between the gut and the body wall, resulting in an enterocoelom.

Additionally, the cleavage pattern in protostomes is spiral and mosaic, whereas in deuterostomes it is radial and regulative. Another distinctive feature is the fate of the blastopore; in protostomes, the blastopore develops into the mouth, whereas in deuterostomes, it becomes the anus, with the mouth forming on the opposite end of the embryo.