30. Overview of Animals

Overview of Animals

Introduction to Zoology: What are Animals?

 No. Metamorphosis produces juveniles, which are sexually immature. 

 No. Larvae are usually the first stage that undergoes metamorphosis. In addition, metamorphosis produces juveniles, which are sexually immature. 

 No. Larvae are usually the first stage that undergoes metamorphosis. Gastrulation is an embryonic process that helps establish the basic body plan. In addition, metamorphosis produces juveniles, which are sexually immature. 

 No. Gastrulation is an embryonic process that helps establish the basic body plan. 

Frogs have all of these stages.

Many young animals are __________, a sexually immature form that is morphologically distinct from the adult stage. These young animals undergo __________ to become __________, which resemble adults but are not yet sexually mature.

One of the characteristics unique to animals is
a. gastrulation.
b. multicellularity.
c. sexual reproduction.
d. flagellated sperm.

Bilateral symmetry in animals is best correlated with
a. an ability to see equally in all directions.
b. the presence of a skeleton.
c. motility and active predation and escape.
d. adaptation to terrestrial environments.

 No. Both animals and protists are eukaryotic. 

 No. The protists from which animals evolved were heterotrophic. 

 No. Reproduction is one of the characteristics common to all life. 

 Animals have more cells than their protist ancestors, and their cells show greater specialization. 

Consider how a colony might differ from a true multicellular organism.

Animals probably evolved from colonial protists. How do animals differ from these protist ancestors?

 No. Only sponges, which lack true tissues, have no germ layers. 

 No. All animals with true tissues have more than one germ layer. 

 No. Animals with radial symmetry have two germ layers. 

 No. There are no animals with four germ layers. 

These animals are triploblastic.

All animals with bilateral symmetry have __________ germ layer(s).

 No. Zygotes undergo either spiral or radial cleavage, but not both. 

 No. Protostomes frequently show spiral cleavage, but the cleavage is not indeterminate. 

 No. This pattern is characteristic of deuterostomes. 

 No. Protostome development is generally determinate, but radial cleavage is less common. 

Snails, with their twisted shells, are protostomes.

The zygotes of many protostomes undergo __________ cleavage and __________ cleavage.

Animal Classification | Evolution | Biology | FuseSchool

 muscle; the outer covering of the animal; the central nervous system 

 No. None of these is correctly associated with the germ layer that gives rise to it. Muscle derives from mesoderm, the outer covering of the animal and the central nervous system derive from ectoderm, and the lining of the gut derives from endoderm. 

 the lining of the digestive tract; muscle; the outer covering of the animal 

 No. Mesoderm does give rise to muscle tissue; however, the other two are not correctly associated with the germ layers that give rise to them. The lining of the digestive tract is derived from endoderm, and the outer covering of the animal derives from ectoderm. 

 the central nervous system; the outer covering of the animal; the lining of the digestive tube 

 No. The outer covering of the animal derives from ectoderm, not mesoderm. 

 muscle; the outer covering of the animal; the lining of the digestive tube 

 No. Muscle derives from mesoderm and the outer covering of the animal derives from ectoderm. 

 the central nervous system; muscle; the lining of the digestive tube 

Ectoderm is the outermost tissue layer of an embryo.

In the embryo of a shark, ectoderm gives rise to __________; mesoderm gives rise to __________; endoderm gives rise to __________.

 No. Spiral cleavage is characteristic of protostomes but not deuterostomes. 

 No. Bilateral animals are triploblastic. 

 No. An anus that develops from the blastopore is characteristic of deuterostomes but not protostomes. 

 No. Indeterminate cleavage is characteristic of deuterostomes but not protostomes. 

This is something that they both produce, but in a different way.

Which of the following is a trait shared by protostomes and deuterostomes?

Based on the tree in Figure 32.11, which statement is false?
a. The animal kingdom is monophyletic.
b. Acoelomate flatworms are more closely related to echinoderms than to annelids.
c. Sponges are basal animals.
d. Bilaterians form a clade

Name two phyla of animals that are radially symmetric and two that are bilaterally symmetric. How do the general lifestyles of radial and bilateral animals differ?

True or false? New major animal body plans have continued to evolve since the Cambrian about 550 million years ago.

Which of the following combinations of phylum and description is correct? 
(A) Echinodermata—radial symmetry as a larva, coelom 
(B) Nematoda—roundworms, internal skeleton 
(C) Platyhelminthes—flatworms, gastrovascular cavity, no body cavity 
(D) Porifera—gastrovascular cavity, coelom

Animals

 No. Arthropods exhibit bilateral symmetry. 

 No. Chordates exhibit bilateral symmetry. 

 No. Molluscs exhibit bilateral symmetry. 

 No. Annelids exhibit bilateral symmetry. 

What type of symmetry do you have?

Which of the following groups does not exhibit bilateral symmetry?

 No. Sponges, like all other animals, are multicellular. 

 No. Sponge cells do not have cell walls. 

 No. Sponges, like many other animals, do not exhibit bilateral symmetry. 

 No. Although sponges lack a true coelom, this does not set them apart from other animals. Several animal phyla contain organisms without true coeloms. 

Recall how sponge cells are organized.

Unlike other animals, sponges __________.

Introduction To Animal Diversity | Iken Edu

Evaluate this statement: Animals evolved from simple to complex.

 No. Protostomes exhibit spiral cleavage. 

 No. Deuterostomes exhibit radial cleavage. 

 No. Endostome is not an appropriate name. 

 All of the listed responses are correct. 

 No. One of the other choices is correct. 

What are the cleavage patterns of protostomes and deuterostomes?

An animal with a true coelom that has __________ cleavage must be a(n) __________.

Overview of Animals - 2

 No. Such a body cavity is characteristic of a coelomate animal. 

No. Then there would be no cavity; animals that lack a body cavity are said to be acoelomate.

 No. This condition does not exist in the animal kingdom. The food tube is not, technically speaking, a body cavity. 

 No. Ectoderm gives rise to the central nervous system. 

 lined on one side by mesoderm and on the other side by endoderm 

A true coelom is lined entirely by mesoderm.

One of the primary developmental/anatomical characteristics distinguishing the major animal phyla is the condition of the body cavity. A pseudocoelomate animal is one in which the body cavity is __________.

Which of the following was probably the least important factor in bringing about the Cambrian explosion?
a. the emergence of predator-prey relationships
b. an increase in the concentration of atmospheric oxygen
c. the movement of animals onto land
d. the origin of Hox genes

Identify the pattern of embryonic development shown in each drawing below and name the phylum (or phyla) that exhibit this pattern. <img class="fr-dib" src="https://lightcat-files.s3.amazonaws.com/problem_images/9d41496beeaff6ea-1677717544267.jpg" style="width: 300px;">

The table below lists the common names of the nine animal phyla surveyed in this chapter. For each phylum, list the key characteristics and some representatives. <img src="https://lightcat-files.s3.amazonaws.com/problem_images/ff4046a9e59ef17d-1672314752583.jpg" alt="" /><img class="fr-dib" src="https://lightcat-files.s3.amazonaws.com/problem_images/fb522c1710ab9b81-1677717460789.jpg" style="width: 300px;">

Overview of Animals - 5

Which of the following animal groups does not have tissues derived from mesoderm? 
a. annelids 
b. echinoderms 
c. cnidarians 
d. flatworms

 No. Protostomes generally have a complete digestive tract. 

 No. Mesoderm does not form all parts of appendages. Besides, many protostomes do not have appendages. 

 Cell fate is determined early during embryonic development. 

Identical twins are not likely to form in protostomes because of this.

Which of the following is characteristic of protostomes?

Which synapomorphy (shared, derived trait) distinguishes animals as a monophyletic group, distinct from choanoflagellates?
a. multicellularity
b. coloniality
c. heterotrophy
d. movement

Overview of Animals - 3

 it allows for a third embryonic germ layer 

 No. Some triploblastic phyla lack a body cavity. 

 it permits the development of an open circulatory system 

 No. Many animals with a true coelom have closed circulatory systems. 

 it is a requirement for a complete digestive tract 

 No. Animals that do not have a true coelom may still have a complete digestive tract. 

 No. Only one of the other choices is correct. 

 it allows room for the development and movement of internal organs 

The coelom forms a space between the internal body organs and the outer body wall.

The presence of a coelom is advantageous because __________.

 a body cavity lined with tissues derived from the endoderm 

 No. A true coelom is a body cavity lined with tissues derived from the mesoderm. 

 a body cavity lined with endoderm and mesoderm 

 No. This does not describe a true coelom but rather a pseudocoelom. 

 No. A true coelom is a fluid-filled body cavity lined with tissue derived from mesoderm. 

A pseudocoelom is a space lined by mesoderm on one side and endoderm on the other.

A true coelom is __________.

Overview of Animals - 4

 No. Eggs and sperm are made by meiosis, whereas cleavage involves mitotic divisions. 

 do not divide according to any recognizable pattern 

No. This is not what indeterminate means. Embryos generally develop along well-controlled pathways.

 form ectoderm but not endoderm or mesoderm 

 No. Embryonic cells produced by indeterminate cleavage can develop into a complete embryo. 

 form mesoderm but not endoderm or ectoderm 

 retain the capacity to develop into a complete embryo 

This process makes identical twins possible.

Indeterminate cleavage produces embryonic cells that __________.

Why is it ecologically significant that animals are heterotrophic and multicellular?

The distinction between sponges and other animal phyla is based mainly on the absence versus the presence of
a. a body cavity.
b. a complete digestive tract.
c. mesoderm.
d. tissues.

 A horseshoe-shaped crown of ciliated tentacles 

 No. This is a characteristic of Lophotrochozoa. 

 No. Segmented bodies are found in many other clades. 

 No. Sponges are the only animal group that lacks true tissues. 

 The secretion of stiff external skeletons that must be shed to permit growth 

The clade Ecdysozoa includes insects.

Which of the following is the defining characteristic of the clade Ecdysozoa for which this group is named?

 Their cells are supported and connected to one another by structural proteins. 

 No. This is true of animals, which lack cell walls. 

 They release enzymes to the outside of the body to aid in digestion. 

 No. This is generally true of fungi but not most animals and plants. 

Think about the structure of their cells.

Which of the listed characteristics is shared by plants, fungi, and animals?

Which of the following was probably an important factor in bringing about the Cambrian explosion? 
(A) the movement of animals onto land 
(B) an increase in the concentration of atmospheric nitrogen 
(C) the emergence of predator-prey relationships 
(D) the origin of bilaterian animals

 No. Cnidarians do not typically have a mesoderm layer. 

 No. Cnidarians exhibit radial symmetry. 

Jellies and sea anemones are cnidarians.

Which of the following is a characteristic of cnidarians?

In a tube-within-a-tube body plan, what is the interior tube derived from?
a. ectoderm
b. mesoderm
c. the coelom
d. endoderm

Introduction to animals

Overview of Animals - 1

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