Exam 30: An Introduction to Animals

What was an early selective advantage of a coelom in animals? A coelom ________.

All sponges ________.

A radula is a specialized feeding organ used to scrape material off of a substrate for ingestion, much like a cheese grater scrapes shreds off of a block of cheese. Snails, which have this structure, are thus which kind of feeder?

Suppose a researcher for a pest-control company developed a chemical that inhibited the development of an embryonic mosquito's endodermal cells. Which of the following would be a likely mechanism by which this pesticide works?

An adult animal that possesses bilateral symmetry would most likely be ________.

Which of the following would you classify as something other than an animal?

Which of the following is a feature of the tube-within-a-tube body plan in most animal phyla?

Which morphological trait evolved more than once in animals, according to the phylogeny based on DNA sequence data found in the accompanying figure?

Following the fusion of gametes in Obelia, the resulting cell divides via mitosis to become a ________.

Both animals and fungi are heterotrophic. What distinguishes animal heterotrophy from fungal heterotrophy is that most animals derive their nutrition by ________.

You have before you a living organism, which you examine carefully. Which of the following should convince you that the organism is acoelomate?

If in the future the current molecular evidence regarding animal origins is further substantiated, what will be TRUE of any contrary evidence regarding the origin of animals derived from the fossil record?

Use the following information to answer the question below. 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 parrotfish and a clownfish. She arranged for daily feedings of copepods and feeder fish. The clownfish readily swims among the tentacles of the sea anemones; the parrotfish avoids them. One hypothesis for the clownfish's apparent immunity is that they slowly build a tolerance to the sea anemone's toxin. A second hypothesis is that a chemical in the mucus that coats the clownfish prevents the nematocysts from being triggered. Which of the following graphs supports the second, but not the first, of these hypotheses?

According to the evidence collected so far, the animal kingdom is ________.

As you are on the way to Tahiti for a vacation, your plane crash-lands on a previously undiscovered island. You soon find that the island is teeming with unfamiliar organisms, and you, as a student of biology, decide to survey them (with the aid of the Insta-Lab Portable Laboratory you brought along in your suitcase). You select three organisms and observe them in detail, making the notations found in the accompanying table. Which organism would you classify as an animal?

Which of the following is (are) unique to animals?

An organism that exhibits cephalization probably also ________.

In examining an unknown animal species during its embryonic development, how can you be sure what you are looking at is a protostome and not a deuterostome?

Which tissue type, or organ, is NOT correctly matched with its germ layer tissue?

Use the following information to answer the question below. Trichoplax adhaerens (Tp) is the only living species in the phylum Placozoa. Individuals are about 1 mm wide and only 27 μm high, are irregularly shaped, and consist of a total of about 2000 cells, which are diploid (2n = 12). There are four types of cells, none of which are nerve or muscle cells, and none of which have cell walls. They move using cilia, and any "edge" can lead. Tp feeds on marine microbes, mostly unicellular green algae, by crawling atop the algae and trapping it between its ventral surface and the substrate. Enzymes are then secreted onto the algae, and the resulting nutrients are absorbed. Tp sperm cells have never been observed, nor have embryos past the 64-cell (blastula) stage. Which of the following Tp traits is different from those of most other animals?