The Correct Answer and Explanation is:
Based on the standard classification of animal phyla in biology, the correct matching is as follows:
- Lophotrochozoa: Matches the description for animals that possess a lophophore feeding structure or a trochophore larval stage.
- Ecdysozoa: Matches the description for animals that grow by molting or shedding their external cuticle, a process known as ecdysis.
- Deuterostomia: Matches the description for animals in which the blastopore, the first opening in the embryo, develops into the anus.
- Basal Animals (or a similar term like Non-Bilateria): Matches the description for early diverging phyla that lack bilateral symmetry, such as those with radial symmetry or asymmetrical body plans.
Explanation
This matching exercise categorizes the major groups within the animal kingdom based on their distinct evolutionary and developmental characteristics. These groupings reflect the modern understanding of animal phylogeny, which is largely based on molecular data.
The Lophotrochozoa is a major superphylum of protostome animals. Its name highlights two key features found within the group, though not all members possess both. The lophophore is a specialized crown of ciliated tentacles used for filter feeding, present in phyla like Bryozoa and Brachiopoda. The trochophore larva is a unique, free swimming larval stage common to animals like mollusks and annelids.
The Ecdysozoa is the other major superphylum of protostomes. Their defining shared characteristic is the process of ecdysis, or molting. These animals possess a tough outer layer, called a cuticle or exoskeleton, which they must periodically shed in order to grow. This clade includes the two most successful animal phyla: Nematoda (roundworms) and Arthropoda (insects, spiders, crustaceans).
The Deuterostomia represents a distinct lineage where embryonic development follows a different path from protostomes. During gastrulation, the initial opening, the blastopore, becomes the anus, while the mouth forms secondarily. This is the origin of the name, which means “second mouth.” This group also typically exhibits radial cleavage in the early embryo. The primary phyla in this clade are the Echinodermata (starfish, sea urchins) and the Chordata (vertebrates and their relatives).
Finally, Basal Animals refers to the phyla that diverged from the main animal lineage before the evolution of bilateral symmetry. This group includes Porifera (sponges), which are asymmetrical and lack true tissues, and Cnidaria (jellyfish, corals), which exhibit radial symmetry. These organisms have simpler body plans compared to the vast majority of animals, which are bilaterians.
