In a tide pool, a student encounters an organism with a hard outer covering that contains a large amount calcium carbonate, an open circulatory system, and gills. The organism could potentially be a crab, a shrimp, a barnacle, or a bivalve. The presence of which of the following structures would allow for the most definitive identification of the organism?

Suppose, while out camping in a forest, you found a chordate with a long, slender, limbless body slithering across the ground near your tent. The organism is most likely ________.

Which of the following structures do vertebrates and tunicates both possess?

Which of the following characteristics is exhibited by the water vascular system of echinoderms?

Which of the following combinations correctly matches a phylum to its description?

Which of the following senses would be most directly affected by removing or damaging an insect’s antennae?

Which of the following characteristics is exhibited by both monotremes and marsupials?

Which of the following characteristics is shared by both cnidarians and flatworms?

Unlike eutherians, both monotremes and marsupials ________.

The evolution of similar insulating skin coverings such as fur, hair, and feathers in mammals and birds is a result of which of the following evolutionary processes?