This class of fishes is characterized by cartilaginous skeletons and includes sharks, skates, rays, and chimaeras.

Transcription factors that control gene expression to make specific regions of the body are called:

All chordates have four derived characters that appear in the embryo. Which of these structures develops into gills, filter feeding structures, and/or parts of the ear and neck?

Which adaptation helps bony fishes control their buoyancy?

This classification refers to all chordates with hinged jaws.

Complete this sentence. In protostomes, cleavage is _____ and _____.

Match the animal phylum to its description. Next to each descriptive phrase, you will see a drop-down menu. Use this menu to select the number that corresponds to the correct animal phylum. Each phylum only has one correct answer, and each answer is only used once. 

Which kind of reproduction occurs when an embryo develops within the uterus and receives nourishment from the mother’s blood via a placenta?

Bilateral animals are divided into three clades. Which clade includes invertebrates with a lophophore feeding structure and/or a trochophore larva?

Animals that develop the mouth before the anus during embryonic development are classified as: