Chapter 24 Introduction to Animals

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Chapter 24 Introduction to Animals

Section 1: Animal Characteristics

Section 2: Animal Body Plans

Section 3: Sponges and Cnidarians

24.1 Animal Characteristics

General Animal Features

Introduction to AnimalsChapter 24

The ancestral animals at the beginning of the evolutionary tree are eukaryotic and multicellular.

They developed adaptations in structure that enabled them to function in numerous habitats.

Feeding and Digestion

Introduction to Animals

Animals are heterotrophic.

The structure or form of an animal’s mouth parts determines how its mouth functions.

24.1 Animal Characteristics

Chapter 24

Support

Introduction to Animals

Invertebrates

Exoskeletons

Hard or tough outer coverings that provide a framework of support

Protect soft body tissues

Provide protection from predators

24.1 Animal Characteristics

Chapter 24

Support

Introduction to Animals

Vertebrates

Endoskeletons

Protect internal organs

Provide support for the body

Provide an internal brace for muscles to pull against

24.1 Animal Characteristics

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Movement

Introduction to Animals

The evolution of nerve and muscle tissues enables animals to move in ways that are more complex and faster than organisms in other kingdoms.

24.1 Animal Characteristics

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Reproduction

Introduction to Animals

Fertilization occurs when the sperm penetrates the egg to form a fertilized egg cell called the zygote.

Internal fertilization

External fertilization

24.1 Animal Characteristics

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Introduction to Animals

Asexual reproduction means that a single parent produces offspring that are genetically identical to itself.

Budding

Fragmentation

Regeneration

Parthenogenesis

24.1 Animal Characteristics

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Early Development

Introduction to Animals

The zygote undergoes mitosis and a series of cell divisions to form new cells.

The cells continue to divide, forming a fluid-filled ball of cells called the blastula.

The blastula continues to undergo cell division as some cells move inward to form a gastrula.

24.1 Animal Characteristics

Chapter 24

Introduction to Animals

24.1 Animal Characteristics

Chapter 24

Introduction to AnimalsChapter 24

Introduction to Animals

Tissue Development

Endoderm inner layer of cells in the gastrula

Ectoderm outer layer of cells in the gastrula

Mesoderm layer of cells between the endoderm

and ectoderm

24.1 Animal Characteristics

Chapter 24

Introduction to Animals

24.1 Animal Characteristics

Chapter 24

24.2 Animal Body Plans

Introduction to Animals

Evolution of Animal Body Plans

Anatomical features in animals’ body plans mark the branching points on the evolutionary tree.

Relationships on this tree are inferred by studying similarities in embryological development and shared anatomical features.

Chapter 24

Introduction to Animals

24.2 Animal Body Plans

Chapter 24

Introduction to Animals

Symmetry Similarity or balance among body structures of organisms Asymmetry Radial symmetry Bilateral symmetry

24.2 Animal Body Plans

Chapter 24

Introduction to Animals

Cephalization

The tendency to concentrate nervous tissue and sensory organs at the anterior end of the animal

24.2 Animal Body Plans

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Introduction to Animals

Body Cavities

Coelomates

Have a fluid-filled cavity with tissue formed from mesodermthat lines and encloses the organs in the coelom

24.2 Animal Body Plans

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Introduction to Animals

Body Cavities

Pseudocoelomates

Have a fluid-filled body cavity that develops between the mesoderm andthe endoderm rather than developing entirely within the mesoderm

24.2 Animal Body Plans

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Introduction to Animals

Body Cavities

Acoelomates

Have solid bodies without a fluid-filled body cavity between the gut and the body wall

24.2 Animal Body Plans

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The mouth develops from the first opening in the gastrula.

Introduction to Animals

Development in Coelomate Animals

Protostomes

Deuterostomes

The anus develops from the first opening in the gastrula.

24.2 Animal Body Plans

Chapter 24

Visualizing Protostome and Deuterostome Development

Introduction to Animals

Segmentation

Segmented animals can be “put together” from a succession of similar parts.

Can survive damage to one segment

Movement is more effective

24.2 Animal Body Plans

Chapter 24

24.3 Sponges and Cnidarians

Introduction to Animals

Sponges

Sponges do not develop tissues.

Collar cells with flagella line the inside of the sponge and whip back and forth drawing water into the body of the sponge.

Water and waste materials are expelled from the sponge through the osculum.

Chapter 24

Introduction to Animals

24.3 Sponges and Cnidarians

Chapter 24

Introduction to AnimalsChapter 24

Introduction to Animals

Filter Feeder

Food particles cling to the cells.

Digestion of nutrients takes place within each cell.

24.3 Sponges and Cnidarians

Chapter 24

Introduction to Animals

Archaeocytes

Specialized cells that secrete spicules, which are the support structures of sponges

Spicules are small, needlelike structures made of calcium carbonate, silica, or a tough fibrous protein called spongin

24.3 Sponges and Cnidarians

Chapter 24

Introduction to Animals

Sponge Diversity

Demospongiae

Calcarea

Hexactinellida

24.3 Sponges and Cnidarians

Chapter 24

Introduction to Animals

Reproduction Reproduce asexually

Fragmentation Budding Gemmules

Reproduce sexually Eggs remain within a sponge. Sperm are released into the water.

24.3 Sponges and Cnidarians

Chapter 24

Introduction to Animals

Cnidarians

Have one body opening and two layers of cells

Outer layer functions in protecting the internal body

Inner layer functions mainly in digestion

24.3 Sponges and Cnidarians

Chapter 24

Introduction to Animals

Feeding and Digestion

Tentacles are armed with stinging cells called cnidocytes.

A nematocyst is a capsule that holds a coiled tube containing poison and barbs.

Water inside an undischarged nematocyst is under an osmotic pressure of more than 150 atmospheres.

24.3 Sponges and Cnidarians

Chapter 24

Introduction to Animals

As the osmotic pressure increases, the nematocyst discharges forcefully.

A barb is capable of penetrating a crab shell.

24.3 Sponges and Cnidarians

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Introduction to Animals

Cells lining the gastrovascular cavity release digestive enzymes over captured prey.

Undigested materials are ejected though the mouth.

24.3 Sponges and Cnidarians

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Introduction to Animals

Response to Stimuli

A nerve net conducts impulses to and from all parts of the body.

The impulses cause contractions of musclelike cells in the two cell layers.

24.3 Sponges and Cnidarians

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Introduction to Animals

Reproduction

Two body forms

Polyp

Medusa

24.3 Sponges and Cnidarians

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Introduction to Animals

The two body forms of cnidarians can be observed in the life cycle of jellyfishes.

24.3 Sponges and Cnidarians

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Introduction to AnimalsChapter 24

Introduction to Animals

Cnidarian Diversity

Hydroids

Jellyfishes

Sea anemones and corals

24.3 Sponges and Cnidarians

Chapter 24

Introduction to Animals

Chapter Resource Menu

Chapter Diagnostic Questions

Formative Test Questions

Chapter Assessment Questions

Standardized Test Practice

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Chapter 24

Which animal is not an invertebrate?

A. lobster

B. shark

C. cicada

D. earthworm

Introduction to Animals

Chapter Diagnostic Questions

Chapter 24

What is the tough outer covering of most invertebrates called?

A. exoskeleton

B. endoskeleton

C. endoderm

D. mesoderm

Introduction to Animals

Chapter Diagnostic Questions

Chapter 24

Which statement is not true of animals?

Introduction to Animals

A. Animal cells have cell walls.

B. Animals are heterotrophic.

D. Animal cells become tissues.

C. Animals probably evolved from earlyprotists.

Chapter Diagnostic Questions

Chapter 24

From which organisms might animals have evolved?

Introduction to Animals

A. animal-like bacteria

B. autotrophic invertebrates

C. colonial protists

D. multicellular fungi

24.1 Formative Questions

Chapter 24

What is a group of cells that performs a specific function?

Introduction to Animals

A. organ

B. tissue

C. gastrula

D. mesoderm

24.1 Formative Questions

Chapter 24

What is one of the most unique characteristics of the animal kingdom?

Introduction to Animals

A. advanced cell structure

B. complex movement

C. sexual reproduction

D. organ development

24.1 Formative Questions

Chapter 24

What is the term for an individual animal that produces both eggs and sperm?

Introduction to Animals

A. acoelomate

B. hermaphrodite

C. heterosexual

D. invertebrate

24.1 Formative Questions

Chapter 24

What form of reproduction produces a new organism from the lost body part of another organism?

Introduction to Animals

A. budding

B. fertilization

C. parthenogenesis

D. regeneration

24.1 Formative Questions

Chapter 24

Which provides the strongest evidence for the relationship between arthropods and roundworms?

Introduction to Animals

A. shared anatomical features

B. shared functional characteristics

C. similar protein structure

D. similar embryological development

24.2 Formative Questions

Chapter 24

Which is the dorsal surface of a hummingbird?

Introduction to Animals

24.2 Formative Questions

Chapter 24

Which organism exhibits cephalization?

Introduction to Animals

A. jellyfish

B. snail

C. sponge

D. starfish

24.2 Formative Questions

Chapter 24

How is deuterostome development different from protostome development shown here?

Introduction to Animals

24.2 Formative Questions

Chapter 24

Introduction to Animals

A. A blastula does not form.

B. The coelom is less advanced.

C. The gut is lined with mesoderm.

D. The blastopore becomes the anus.

24.2 Formative Questions

Chapter 24

Why are sponges most distantly related to the rest of the animals?

Introduction to Animals

A. They are not multicellular.

B. They do not have true tissues.

C. Their embryos have a mesoderm.

24.3 Formative Questions

D. They arose from a different protistancestor.

Chapter 24

What is the term for organisms that remain attached to one place?

Introduction to Animals

A. sessile

B. tactile

C. axiallary

D. sedentary

24.3 Formative Questions

Chapter 24

What provides the energy for the discharge of a cnidarian’s nematocysts?

Introduction to Animals

A. muscle fibers

B. hydraulic forces

C. osmotic pressure

D. protein springs

24.3 Formative Questions

Chapter 24

Which is the dominant stage in the life cycle of a sea anemone?

Introduction to Animals

A. bud

B. hydroid

C. medusa

D. polyp

24.3 Formative Questions

Chapter 24

Identify the term that is used to describe the evolutionary history of a particular species.

Introduction to Animals

A. genealogy

B. biology

C. phylogeny

D. paleontology

Chapter Assessment Questions

Chapter 24

Distinguish between asymmetry, radial symmetry and bilateral symmetry and givean example of each.

Introduction to Animals

Chapter Assessment Questions

Chapter 24

Introduction to Animals

Answer: Asymmetry – There is no symmetry orbalance in body structure and no shape. Example: sponge

Radial symmetry – The animal’s body can be divided along any plane through a central axis into equal halves. Example: jellyfish

Bilateral symmetry – The animal can bedivided into mirror image halves alongone plane. Example: dog

Chapter Assessment Questions

Chapter 24

Explain why it would be beneficial for a fish to lay many eggs when fertilization is external.

Introduction to Animals

Answer: Some of the eggs will float away, beeaten or destroyed, so laying a large number of eggs makes it more likely that some will be fertilized and hatch.

Chapter Assessment Questions

Chapter 24

Which is not a characteristic that definesall animals?

Introduction to Animals

A. carnivorous

B. eukaryotic

C. heterotrophic

D. multicellular

Standardized Test Practice

Chapter 24

At which stage is the developing animal an embryo?

Introduction to Animals

Standardized Test Practice

Chapter 24

Which reproduces by internal fertilization?

Introduction to Animals

A. bear

B. clam

C. fish

D. frog

Standardized Test Practice

Chapter 24

What is the most recent evolutionary development exhibited by both arthropods and echinoderms?

Introduction to Animals

A. a body cavity

B. a coelom

C. segmentation

D. protostome development

Standardized Test Practice

Chapter 24

Which organisms are most closely related to roundworms?

Introduction to Animals

A. sponges

B. cnidarians

C. flatworms

D. arthropods

Standardized Test Practice

Chapter 24

What characteristic do sponges and cnidarians have in common?

Introduction to Animals

A. body symmetry

B. single body opening

C. cell layers organized into tissues

D. sessile attachment to surfaces

Standardized Test Practice

Chapter 24

Introduction to Animals

Glencoe Biology Transparencies

Chapter 24

Introduction to Animals

Image Bank

Chapter 24

invertebrate

exoskeleton

endoskeleton

vertebrate

hermaphrodite

zygote

internal fertilization

external fertilization

blastula

gastrula

endoderm

ectoderm

mesoderm

Introduction to Animals

Vocabulary

Section 1

Chapter 24

symmetry

radial symmetry

bilateral symmetry

anterior

posterior

cephalization

dorsal

ventral

coelom

pseudocoelom

acoelomate

protostome

deuterostome

Introduction to Animals

Vocabulary

Section 2

Chapter 24

filter feeder

sessile

cnidocyte

nematocyst

gastrovascular cavity

nerve net

polyp

medusa

Introduction to Animals

Vocabulary

Section 3

Chapter 24

Introduction to Animals

Animation

Chapter 24

Cell Differentiation in Animal Development

A Sponge

A Cnidarian

Visualizing Protostome and Deuterostome Development