Which of the following is true of members of the phylum Cnidaria?

They may use a gastrovascular cavity as a hydrostatic skeleton.

Which of the following is a diploblastic phylum of aquatic predators?

Cnidaria

Use the following information to answer the question(s) 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.

One day, Tommy, a student in an undersupervised class of forty fifth graders, got the urge to pet Nemo (the clownfish), 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 _____.

nematocysts

Use the following information to answer the question(s) 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 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 medusa stage

Which of the following is characteristic of the phylum Platyhelminthes?

They are dorsoventrally flattened.

Members of the phylum Mollusca _____.

are soft-bodied and often covered by a shell

A marine biologist dredges up a small animal from the bottom of the ocean. It is uniformly segmented, with short, stiff appendages and soft, flexible skin. It has a complete digestive system and a closed circulatory system, plus multiple true coeloms. Based on this, you determine that the animal must be a(n) _____.

annelid

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?

It has not coelom.

Which structure do sea slugs use to feed on their prey?

a radula

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

bivalves

Which characteristic is shared by cnidarians and flatworms?

a digestive system with a single opening

What structure is responsible for gas exchange in most spiders?

book lungs

You find a multi-legged animal in your garden and want to determine if it is a centipede or a millipede. You take the animal to a university where a myriapodologist quickly tells you that you have found a centipede. Which of the following may have allowed her to make this distinction?

poisonous fangs

All arthropods _____.
1) undergo complete metamorphose
2) have jointed appendages
3) molt
4) have segmented bodies
5) have an exoskeleton or cuticle

2, 3, 4, 5

What would be the most direct effect of removing or damaging an insect's antennae? The insect would have trouble _____.

smelling

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?

Nematoda

The water vascular system of echinoderms _____.

functions in locomotion and feeding

Which of the following combinations correctly matches a phylum to its description?

Echinodermata – bilateral symmetry as a larva, water vascular system

Sponges _____.

have larvae which are motile and move via the motion of cilia

What would be the best anatomical feature to look for to distinguish a gastropod from a chiton?

number of shell plates

Planarians lack dedicated respiratory and circulatory systems because _____.

none of their cells are far removed from the gastrovascular cavity or from the external environment

Which of the following are thought to be most closely related to humans?

sea stars

The bivalves started to die one by one; only the undamaged shells remained. To keep the remaining bivalves alive, the teacher would most likely need to remove the _____.

sea star

Nematodes and arthropods both _____.

grow by shedding their exoskeleton