Exam 33: An Introduction to Invertebrates

All insects ________.

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 ________.

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

Which of the following statements is correct with respect to the evolutionary relationship between chordates and 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 most likely reach the skin of sea slugs through branches of the ________.

Sponges ________.

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. If the dinoflagellate-containing sea slug P. ianthina preys on coral animals, then it would be most surprising to find that ________.

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 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 antennae of insects have a function most similar to that of ________.

The water vascular system of echinoderms

Which one of these mollusc groups can be classified as suspension feeders?

Which of the following can be found in the mesohyl of a sponge?

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. The feeding stage of cycliophorans ________.

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. How would a terrestrial centipede most likely benefit from the ability to close its spiracles? Closing spiracles would ________.

Against which hard structure do the circular and longitudinal muscles of annelids work?

In a tide pool, a student encounters an organism with a hard outer covering that contains much 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 certain identification of the organism?

If a lung were to be found in a mollusc, where would it be located?

The sea slug Elysia chorotica has no nematocysts or dinoflagellates but, rather, has "naked" chloroplasts in its skin. The chloroplasts are all that remain of the seaweed (Vaucheria sp.) that Elysia feeds upon. The chloroplasts are transferred to the skin; consequently, this slug is green. It spends most of its time basking in shallow water on the surface of seaweeds. How should we expect its chloroplasts to benefit the Elysia sea slug?

Whiteflies are common pest insects found on cotton, tomato, poinsettia, and many other plants. Nymphs are translucent and mostly sessile, feeding on their host plant's phloem (sap) from the undersides of leaves. They undergo incomplete metamorphosis into winged adults. Because whitefly nymphs cannot escape predation by moving, you hypothesize that their translucent bodies make them hard to spot by predators. How could you directly test this hypothesis?