Question 1

Arthropods have a unique exoskeleton made of chitin. This shows that arthropods are more closely related to fungi (which also produce chitin) than they are to either cnidarians or lophotrochozoans.

Accepted Answer

The presence of chitin in both arthropods and fungi is an example of convergent evolution, not a direct indicator of close evolutionary relationship. Arthropods are more closely related to other animals, including cnidarians and lophotrochozoans, than they are to fungi, as they share a more recent common ancestor with these animals.

Question 2

What structure would you expect to find in every type of mollusk (i.e., gastropods, cephalopods, and bivalves)?

Accepted Answer

Every type of mollusk is characterized by the presence of a mantle, which is a thin fleshy layer that covers and protects the soft body of the animal. The mantle secretes the shell in bivalves and some gastropods, and also assists in locomotion and respiration. Tentacles and single-lens eyes are present only in some groups of mollusks, while valves and hinges are exclusive to bivalves.

Question 3

Insects exchange gases through pores called _____, which connect to an internal system of tubes called _____, which are in turn connected to respiring tissues.

Accepted Answer

Insects exchange gases through pores called spiracles, which connect to an internal system of tubes called tracheae, which are in turn connected to respiring tissues.

Question 4

Which of the following relationships between groups is CORRECT?

Accepted Answer

B) Crustaceans, such as crabs and lobsters, are indeed a group within the arthropods, which also include insects and spiders. D) Sea stars (starfish) belong to the echinoderms, a group characterized by radial symmetry and a water vascular system. E) Tunicates, or sea squirts, are marine organisms that belong to the phylum Chordata, which includes all animals with a notochord at some stage of their development.

Question 5

Which of the following statements is true of BOTH mollusks and annelids?

Accepted Answer

Both annelids and mollusks have a trochophore larval stage during their development.

Question 6

Which of the following statements is TRUE of chelicerates?

Accepted Answer

Chelicerates, which include spiders, ticks, and scorpions, have two main body segments and do not possess antennae, which are characteristics found in insects and crustaceans.

Question 7

The myriapods include the _____, which are fast-moving predators with front legs modified into venomous fanglike organs, and _____, which are slow-moving herbivores.

Accepted Answer

Centipedes are fast-moving predators with front legs modified into venomous fanglike organs, while millipedes are slow-moving herbivores.

Question 8

Insects are likely so successful because of which adaptations that allow them to live in a wide range of habitats?

Accepted Answer

The answer of Insects are likely so successful because of...

Question 9

Examine Figure 44.25 below.  According to this phylogeny, the sister group to the hemichordates is the:

Accepted Answer

The answer of Examine Figure 44.25 below.  According to...

Question 10

_____, which include lobsters and crabs, have _____ legs and, in the ocean, fill many of the ecological roles filled by insects on land.

Accepted Answer

Crustaceans, such as lobsters and crabs, have branched legs and occupy many ecological roles in the ocean similar to those of insects on land.

Question 11

Within insects, the main evolutionary dividing line is between those that

Accepted Answer

The main evolutionary dividing line within insects is between those that undergo metamorphosis and those that do not. Insects that undergo metamorphosis, such as butterflies and beetles, undergo a dramatic change in form and often ecological niche as they progress through their life stages from egg to larva to pupa to adult. In contrast, insects that do not undergo metamorphosis, such as grasshoppers and crickets, generally hatch from eggs into nymphs that resemble miniature adults and undergo a series of molts until they reach their full size and reproductive potential. The presence or absence of wings is not a reliable indicator of evolutionary relationships among insects, as some groups have evolved to lose or reduce their wings over time. Similarly, while the presence of an eggshell is a defining feature of insect eggs, it is not a major factor in the overall evolutionary diversity of the group.

Question 12

All lophotrochozoans have:

Accepted Answer

Lophotrochozoans are a group of animals that include mollusks, annelids, and flatworms. They all possess bilateral symmetry, which means their bodies can be divided into two symmetrical halves. They also have complex organs, such as a digestive system, circulatory system, and nervous system. The other options are incorrect, as lophotrochozoans do not exhibit radial symmetry or primitive organs.

Question 13

Imagine that scientists have discovered annelid life on a new planet. Remarkably, these worms are large in size, lack mouths, and appear to form symbioses with certain bacterial species. These worms MOST resemble _____ on Earth.

Accepted Answer

The description matches with vestimentiferan worms, which are found near deep-sea hydrothermal vents and lack a digestive system, obtaining nutrition from their bacterial symbionts. They can grow up to several meters in length. None of the other options have a similar match to the description given.

Question 14

A close evolutionary relationship between annelids and mollusks is suggested by the presence of a _____ larva in both phyla as well as by molecular sequence comparisons.

Accepted Answer

The trochophore larva is a distinctive larval form found in both annelids and mollusks, providing evidence for a close evolutionary relationship between the two phyla. Molecular sequence comparisons have also supported this relationship. The other answer choices are not as directly linked to the evolutionary relationship between annelids and mollusks.

Question 15

The group mollusks includes:

Accepted Answer

Mollusks include gastropods (snails, slugs) and cephalopods (octopuses, squids), as well as bivalves (clams, oysters) and other groups. Sponges and placozoans are not mollusks, and crustaceans and starfish belong to other phyla.

Question 16

Both vertebrates and echinoderms (sea urchins and sea stars) are deuterostomes.

Accepted Answer

Both vertebrates and echinoderms share the characteristic of deuterostomy. During embryonic development, their blastopore becomes the anus and the mouth forms separately. This is in contrast to protostomes, where the blastopore becomes the mouth and the anus forms separately.

Question 17

The majority of all known animal species are:

Accepted Answer

Insects make up the majority of all known animal species, with over one million species identified so far. Other groups, such as vertebrates and cnidarians, have far fewer identified species in comparison.

Question 18

_____, such as sea squirts, share features of the chordate body plan during early development.

Accepted Answer

Tunicates, also known as sea squirts, share features of the chordate body plan during early development but have a more simplified body plan as adults. Therefore, the best choice is A) Tunicates.

Question 19

Ecdysozoans include insects and make up more than half of all known animal species.

Accepted Answer

Ecdysozoans are a group of animals that are characterized by their ability to shed their outer layer, or cuticle, through a process called ecdysis. This group includes insects, as well as other arthropods such as spiders and crustaceans, as well as a number of other invertebrate species. Ecdysozoans are some of the most diverse and abundant animals on the planet, making up more than half of all known animal species.

Question 20

Bilaterians develop specialized organs because they have:

Accepted Answer

Bilaterians develop specialized organs because they have three germ layers (ectoderm, mesoderm, and endoderm), which allow for more complex tissue and organ development.

Quiz 44: Animal Diversity