Which of these familiar animals are all protostomes?


a. clams, shrimp, goldfish, leeches
b. butterflies, spiders, snakes, crabs
c. earthworms, snails, beetles, squid

Verified step by step guidance

1. Identify the key characteristic of protostomes, which is that during embryonic development, the mouth develops before the anus.
2. Review each group of animals listed in the options to determine if they all exhibit this characteristic of protostomes.
3. Exclude any groups that contain deuterostomes, where the anus develops before the mouth. For example, vertebrates like fish and snakes are deuterostomes.
4. Focus on invertebrate groups, as most protostomes are invertebrates, including mollusks, annelids, and arthropods.
5. Confirm that the correct option only includes animals that are classified as protostomes, such as earthworms (annelids), snails (mollusks), beetles (arthropods), and squid (mollusks).

Key Concepts

Protostomes

Protostomes are a major group of animals characterized by their embryonic development. In protostomes, the mouth develops from the first opening in the embryo, known as the blastopore, while the anus forms later. This group includes diverse organisms such as mollusks, annelids, and arthropods, which exhibit a wide range of body plans and adaptations.

Animal Classification

Animal classification is the systematic categorization of animals based on shared characteristics and evolutionary relationships. It involves grouping animals into taxa such as phyla, classes, and orders. Understanding the classification helps in identifying which animals belong to the protostome group and differentiating them from deuterostomes, where the anus develops first.

Examples of Protostomes

Common examples of protostomes include clams, shrimp, and earthworms. These animals exhibit key features such as a coelom (body cavity) and segmented bodies in some cases. Recognizing these examples is crucial for answering questions about which animals belong to the protostome category, as it helps in distinguishing them from deuterostomes like vertebrates.