Question 1

Which characteristic is not associated with a parasitic lifestyle as seen in tapeworms and flukes?

Accepted Answer

A complex digestive system is not associated with a parasitic lifestyle as tapeworms and flukes rely on their host's digestive system for nutrients and do not have one of their own.

Question 2

Which feature is an adaptation found in flatworms that is associated with a parasitic lifestyle?

Accepted Answer

Flatworms, particularly parasitic ones like tapeworms, absorb nutrients directly through their body surface, which is an adaptation to living inside a host where they are surrounded by pre-digested nutrients.

Question 3

You discover a new organism with the following characteristics: a wormlike body with a fluid-filled cavity,a feeding organ that looks like a proboscis,and a complete digestive tract.The organism is most likely a(n)

Accepted Answer

The characteristics of a wormlike body with a fluid-filled cavity, a feeding organ that looks like a proboscis, and a complete digestive tract are all present in ribbon worms, also known as nemertea. Annelids also have a segmented wormlike body and a complete digestive tract, but they do not have a feeding organ that looks like a proboscis. Flatworms and nematodes have different body shapes and do not have a fluid-filled cavity. Horsehair worms have a thread-like body and do not have a complete digestive tract.

Question 4

Wormlike organisms are very common,but some phyla,such as _______,contain only other kinds of body plans.

Accepted Answer

Bryozoans are a phylum of aquatic invertebrates that do not have wormlike bodies. They are colonial animals with unique body plans consisting of tiny individual organisms called zooids that work together to form a larger structure. Nematodes, nemerteans, annelids, and polychaetes all have wormlike bodies.

Question 5

The type of symmetry possessed by the cnidarians is known as _______ symmetry.

Accepted Answer

Cnidarians, such as jellyfish and sea anemones, have radial symmetry, meaning their body parts are arranged around a central axis. They have no distinct front or back, and can be divided into two identical halves by multiple planes passing through the central axis.

Question 6

Which statement about bryozoans is true?

Accepted Answer

Bryozoans are mainly marine animals found in both shallow and deep waters. They are colonial organisms made up of individuals called zooids that live together in a common exoskeleton. Each zooid has a lophophore, a ciliated feeding structure.

Question 7

Which organisms are members of the lophotrochozoan lineage?

Accepted Answer

Lophotrochozoan lineage is a group of animals that share certain characteristics in embryonic development and molecular biology. Organisms belonging to this lineage include mollusks, annelids, flatworms, and brachiopods. Sponges, vertebrates, and cnidarians are not members of the lophotrochozoan lineage, while insects may or may not be depending on the classification system being used.

Question 8

Which feature is not associated with the rotifers?

Accepted Answer

Rotifers have bilateral symmetry, not radial symmetry.

Question 9

Which trait unites the deuterostomes but not the protostomes?

Accepted Answer

Deuterostomes all have a dorsal nervous system, while protostomes have a ventral nervous system.

Question 10

Which feature is not associated with the annelids?

Accepted Answer

Trichinosis is a parasitic disease caused by a worm, but it is not associated with annelids. Annelids are characterized by their segmentation, closed circulatory system, coelom, and hydrostatic skeleton.

Question 11

Which group includes the fewest species?

Accepted Answer

Bryozoans only have around 4,000 species, whereas mollusks have over 100,000 species, arthropods have over 1 million species, nematodes have over 1 million species, and lophotrochozoans have over 130,000 species.

Question 12

The cnidarians are considered to be the sister group to which taxon?

Accepted Answer

Cnidarians are considered to be the sister group to bilaterians, which includes most of the animals we commonly think of (such as insects, mammals, and reptiles). This means that cnidarians and bilaterians share a common ancestor that was more recent than the common ancestor of cnidarians and any other animal group, including sponges and placozoans.

Question 13

Many lineages of lophotrochozoans have a free-living larva known as a

Accepted Answer

Lophotrochozoans have a characteristic ciliated larval stage called a trochophore, which is free-living and commonly found in species like mollusks and annelids.

Question 14

Which statement about nematocysts is true?

Accepted Answer

Nematocysts are specialized organelles found in the cnidocytes of cnidarians (such as jellyfish, sea anemones, and corals) that are used in the capture of prey. They contain a coiled, thread-like tube called a cnida that can be discharged to immobilize or kill prey, or for defense.

Question 15

In the history of animals,which characteristic arose after the evolution of the cnidarians?

Accepted Answer

The evolution of three distinct body layers (ectoderm, mesoderm, and endoderm) occurred after the evolution of cnidarians. Cnidarians have only two distinct tissue layers.

Question 16

Which is a cnidarian group of geological importance because of its contributions to the formation of coral islands and atolls?

Accepted Answer

Anthozoans, specifically the reef-building corals, play a vital role in the formation of coral islands and atolls by secreting calcium carbonate skeletons that accumulate over time and contribute to the growth of the structures.

Question 17

Which characteristic is not a feature of the sponges?

Accepted Answer

Sponges do not have a true gastrovascular cavity like other animals such as cnidarians. Instead, they rely on the movement of water through their body to obtain nutrients and oxygen.

Question 18

Which feature is not a characteristic of the phoronids?

Accepted Answer

Phoronids are filter feeders, not active foragers or carnivores. They use their lophophore to filter plankton and other small particles from the water.

Question 19

Which taxon has the largest number of described species?

Accepted Answer

Cnidarians have the largest number of described species, with approximately 11,000 species recognized.

Question 20

Which characteristic is not a feature of the ctenophores?

Accepted Answer

The characteristic of having a notochord is not a feature of ctenophores. While ctenophores are early diverging animals, they do not possess a notochord as seen in chordates. Ctenophores have diploblastic development with the presence of mesoglea and use beating cilia for locomotion.

Quiz 23: Animal Origins and Diversity