Exam 33: An Introduction to Invertebrates

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

A student observes a wormlike organism crawling about on dead organic matter. Later, the organism sheds its outer covering. One possibility is that the organism is a larval insect (like a maggot). However, it might be a member of the phylum ________, and one way to distinguish between the two possibilities is by looking for ________.

Corals are most closely related to which group?

A terrestrial animal species is discovered with the following larval characteristics: exoskeleton, system of tubes for gas exchange, and modified segmentation. A knowledgeable zoologist should predict that the adults of this species would also feature

The members of which clade in the phylum Cnidaria occur only as polyps?

A stalked, sessile marine organism has several feathery feeding structures surrounding an opening through which food enters. The organism could potentially be a cnidarian, a lophophorate, a tube-dwelling worm, a crustacean, or an echinoderm. Which of the following traits, if found in this organism, would allow the greatest certainty of identification?

Which clade in the phylum Cnidaria includes "jellies" with rounded (as opposed to boxlike)medusae?

Planarians lack dedicated respiratory and circulatory systems because

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

Among the invertebrate phyla, phylum Arthropoda is unique in possessing members that have

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 nontaxonomic term sea slug encompasses a wide variety of marine gastropods. One feature they share as adults is the lack of a shell. We 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. -Sea slugs can obtain nematocysts by preying on sea

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. -If the teacher wanted to show the students what a lophophore is and how it works, the teacher would point out a feeding

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 x 10⁵ cells/mg of sea slug protein) can promote sea slug survival. -If 100,000 sea slug cells together contain 1.0 mg of protein, then what is the minimum number of dinoflagellates per sea slug cell that constitutes a "high," and therefore beneficial, population?

The crown-of-thorns sea star, Acanthaster planci, preys on the flesh of live coral. At times, these sea stars undergo poorly understood population explosions. What impact should such explosions have on those sea slugs that bear cerata (cerata contain nematocysts)? Population explosions of this sea star should

How many of the following can be used to distinguish a nematode worm from an annelid worm? 1)type of body cavity 2)number of muscle layers in the body wall 3)presence of segmentation 4)number of embryonic tissue layers 5)shape of worm in cross-sectional view

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 noticed the presence of many empty exoskeletons attached to emergent vegetation. These exoskeletons looked exactly like those of the largest of the "mystery organisms" she had seen in the pond. They also looked similar to the bodies of the dragonflies that patrolled the surface of the pond. If Sarah had learned a lot from her college biology class, what should she have concluded about the mysterious pond organisms?

Nudibranchs, a type of predatory sea slug, can have various protuberances (i.e., extensions) on their dorsal surfaces. Rhinophores are paired structures, located close to the head, which bear many chemoreceptors. Dorsal plummules, 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

If nudibranch rhinophores are located at the anteriors of these sea slugs, then they contribute to the sea slugs'

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

Aside from the density of dinoflagellates in P. ianthina skin, how many of the following factors can affect whether or not the endosymbiotic dinoflagellates promote the sea slug's survival (assuming latitudes above or below Earth's equator)? 1)day length 2)height of sun above the horizon 3)cloud cover 4)depth at which P. ianthina lives 5)water clarity