Clades and Developmental Patterns in Animals

The tutorial explores Nephrozoa, focusing on Protostomia and Deuterostomia. It delves into Spiralia, a clade within Protostomia, highlighting its major phyla like Mollusca and Annelida. The concept of spiral cleavage is explained, including its types and significance. The tutorial discusses the major clades within Spiralia: Gnathifera, Rouphozoa, and Lophotrochozoa, and addresses classification challenges. The session concludes with an introduction to Platyhelminthes, setting the stage for future tutorials.

What are the two main divisions of Nephrozoa?

• Gnathifera and Rouphozoa

• Spiralia and Ecdysozoa

• Mollusca and Annelida

• Protostomia and Deuterostomia

Which pattern of development is characteristic of Spiralia?

• Radial cleavage

• Asymmetrical division

• Spiral cleavage

• Bilateral symmetry

In unequal cleavage, which blastomere is larger?

• D blastomere

• C blastomere

• A blastomere

• B blastomere

Which clade includes animals with chitinous jaws?

• Lophotrochozoa

• Ecdysozoa

• Gnathifera

• Rouphozoa

Which clade includes segmented worms and mollusks?

• Gnathifera

• Rouphozoa

• Lophotrochozoa

• Ecdysozoa

What is the relationship between Lophotrochozoa and Spiralia?

• Lophotrochozoa is a sister group to Ecdysozoa

• Lophotrochozoa is a sister group to Spiralia

• Lophotrochozoa is a subgroup within Spiralia

• Lophotrochozoa is unrelated to Spiralia

What is a synapomorphy of the clade Spiralia?

• Bilateral symmetry

• Spiral cleavage

• Asymmetrical division

• Radial symmetry

Which animals are considered tetrapods despite losing limbs?

• Rotifers and jaw worms

• Snakes and whales

• Earthworms and leeches

• Flatworms and ribbon worms

What is the significance of spiral cleavage in evolutionary terms?

• It is unique to all animal clades

• It is a feature of deuterostomes

• It is a derived characteristic of Spiralia

• It is found in all protostomes

Which phylum will be covered next in the series?

• Platyhelminthes

• Rotifera

• Mollusca

• Annelida