Exam 33: An Introduction to Invertebrates

Use the information and figure to answer the following question. The sea slug Pteraeolidia ianthina can harbor living dinoflagellates (photosynthetic protists)in its skin. These endosymbiotic dinoflagellates reproduce quickly enough to maintain their populations. Low populations do not affect the sea slugs very much, but high populations (> 5 × 10⁵ cells/mg of sea slug protein)can promote sea slug survival. Percent of sea slug respiratory carbon demand provided by indwelling dinoflagellates. According to the graph, during which season(s)of the year is the relationship between the sea slug and its dinoflagellates closest to being commensal?

Use the following information to answer the question. An elementary school science teacher decided to liven up the classroom with a saltwater aquarium. Knowing that saltwater aquaria can be quite a hassle, the teacher proceeded stepwise. First, the teacher conditioned the water. Next, the teacher decided to stock the tank with various marine invertebrates, including a polychaete, a siliceous sponge, several bivalves, a shrimp, several sea anemones of different types, a colonial hydra, a few coral species, an ectoproct, a sea star, and several herbivorous gastropod varieties. Lastly, she added some vertebrates-a parrot fish and a clown fish. She arranged for daily feedings of copepods and feeder fish. If the teacher wanted to show the students what a lophophore is and how it works, the teacher would point out a feeding ________.

Large animals need specialized organs for gas exchange because ________.