Exam 33: An Introduction to Invertebrates

Use the information to answer the following question. The nontaxonomic term sea slug encompasses a wide variety of marine gastropods. One feature they share as adults is the lack of a shell. One might think, therefore, that they represent defenseless morsels for predators. In fact, sea slugs have multiple defenses. Some sea slugs prey on sponges and concentrate sponge toxins in their tissues. Others feed on cnidarians, digesting everything except the nematocysts, which they then transfer to their own skins. Whereas the most brightly colored sea slugs are often highly toxic, others are nontoxic and mimic the coloration of the toxic species. Their colors are mostly derived from pigments in their prey. There are also sea slugs that use their coloration to blend into their environments. This nudibranch, a type of sea slug, has many reddish cerata on its dorsal surface, as well as two white-tipped rhinophores located on the head. The nematocysts of sea slugs should be most effective at protecting individual sea slugs from predation if the predators ________.

Use the following information to answer the question. A farm pond, usually dry during winter, has plenty of water and aquatic pond life during the summer. One summer, Sarah returns to the family farm from college. Observing the pond, she is fascinated by some six-legged organisms that can crawl about on submerged surfaces or, when disturbed, seemingly "jet" through the water. Watching further, she is able to conclude that the "mystery organisms" are ambush predators, and their prey includes everything from insects to small fish and tadpoles. Sarah observed that the mystery pond organisms never come up to the pond's surface. If she catches one of these organisms and observes closely, perhaps dissecting the organism, she should find ________.

Use the graph to answer the following question. Which of the following factors, when used to label the horizontal axis of the graph, would account most directly for the shape of the plot?

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. One day, Tommy, a student in an undersupervised class of 40 fifth graders, got the urge to pet Nemo (the clown fish), who was swimming among the waving petals of a pretty underwater "flower" that had a big hole in the midst of the petals. Tommy giggled upon finding that these petals felt sticky. A few hours later, Tommy was in the nurse's office with nausea and cramps. Microscopic examination of his fingers would probably have revealed the presence of ________.

Which of the following changes would lead to an increase in surface-area-to-volume ratios?

Use the following information to answer the question. The phylum Cycliophora was discovered in 1995. They are tiny organisms that live in large numbers on the outsides of the mouthparts and appendages of lobsters. The feeding stage permanently attaches to the lobster via an adhesive disk and collects scraps of food from its host's feeding by capturing the scraps in a current created by a ring of cilia. The body is saclike and has a U-shaped intestine that brings the anus close to the mouth. Cycliophorans are coelomates, do not molt (though their host does), and their embryos undergo spiral cleavage. Which of these, if discovered among cycliophorans, would cause the most confusion concerning our current understanding of cycliophoran taxonomy?

One should expect to find cilia associated with the feeding apparatus of ________.

Without genetic variation, evolution cannot occur. Sexual reproduction leads to increased genetic variation, but male bdelloid rotifers have never been observed. Which of the following are correct statements with regard to evolution in bdelloid rotifers?

You find what you believe is a new species of animal. Which of the following characteristics would enable you to argue that it is more closely related to a flatworm than it is to a roundworm?

Use the following information to answer the question. Nudibranchs, a type of predatory sea slug, can have various protuberances (that is, extensions)on their dorsal surfaces. Rhinophores are paired structures, located close to the head, which bear many chemoreceptors. Dorsal plumules, usually located posteriorly, perform respiratory gas exchange. Cerata usually cover much of the dorsal surface and contain nematocysts at their tips. The claws on the foremost trunk segment of centipedes have a function most similar to that of ________.

Which phylum is characterized by animals that have a segmented body?

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. The teacher and class were especially saddened when the colonial hydrozoan died. They had watched it carefully, and the unfortunate creature never even got to produce offspring by budding. Yet, everyone was elated when one of the students noticed a small colonial hydrozoan growing in a part of the tank far from the location of the original colony. The teacher was apparently unaware that these hydrozoans exhibit ________.

A land snail, a clam, and an octopus all share

As you are walking along a beach, you find an animal and believe that it belongs to the class Asteroidea. Which of the following characteristics would support your hypothesis that the animal is a sea star and not another type of echinoderm?

Which of the following combinations of phylum and description is incorrect?

Use the following information and figure to answer the question. Aphids are Hemiptera that suck phloem liquid from plants. Ants are often seen tapping the posterior end of the aphid and collecting the liquid that is released from the aphid's digestive system. In an effort to understand this interaction, several researchers measure the survival rates of aphid populations when ants were present and when they were excluded. Their results are shown. Which of the following conclusions is most likely correct?

The heartworms that can accumulate within the hearts of dogs and other mammals have a pseudocoelom, an alimentary canal, and an outer covering that is occasionally shed. To which phylum does the heartworm belong?

Use the following information and figures to answer the question. Many terrestrial arthropods exchange gases with their environments by using tracheae, tubes that lead from openings (called spiracles)in the animal's exoskeleton or cuticle directly to the animal's tissues. Some arthropods can control whether their spiracles are opened or closed; opening the spiracles allows the carbon dioxide produced in the tissues to travel down the tracheae and be released outside the animal. Klok et al. measured the carbon dioxide emitted over time (represented by ⱽCO₂)by several species of centipedes. The figures present graphs of their results for two species, Cormocephalus morsitans and Scutigerina weberi. Look at the graph for Cormocephalus morsitans in the figure. What is the best interpretation of these results?

Echinoderms show enormous diversity in which of the following traits?

What would be the most effective method of reducing the incidence of blood flukes in a human population?