reece •urry• cain • wasserman •minorsky• jackson 32...campbell biology reece •urry•...

CAMPBELL

BIOLOGY Reece • Urry • Cain • Wasserman • Minorsky • Jackson

© 2014 Pearson Education, Inc.

TENTH EDITION

32 An Overview of Animal Diversity

Lecture Presentation by Nicole Tunbridge and Kathleen Fitzpatrick


A Kingdom of Consumers

!  Most animals are mobile and use traits such as strength, speed, toxins, or camouflage to detect, capture, and eat other organisms

!  For example, the chameleon captures insect prey with its long, sticky, quick-moving tongue

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Figure 32.1

3


Figure 32.1a

4


Concept 32.1: Animals are multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers !  There are exceptions to nearly every criterion for

distinguishing animals from other life-forms

!  Several characteristics, taken together, sufficiently define the group

5


Nutritional Mode

!  Animals are heterotrophs that ingest their food

6


Cell Structure and Specialization

!  Animals are multicellular eukaryotes

!  Their cells lack cell walls

!  Their bodies are held together by structural proteins such as collagen

!  Nervous tissue and muscle tissue are unique, defining characteristics of animals

!  Tissues are groups of similar cells that act as a functional unit

7


Reproduction and Development

!  Most animals reproduce sexually, with the diploid stage usually dominating the life cycle

!  After a sperm fertilizes an egg, the zygote undergoes rapid cell division called cleavage

!  Cleavage leads to formation of a multicellular, hollow blastula

!  The blastula undergoes gastrulation, forming a gastrula with different layers of embryonic tissues

8


Figure 32.2-1 Zygote

Cleavage Eight-cell

stage

9



Cleavage Eight-cell

stage

Cleavage Blastocoel

Cross section of blastula

Blastula

10



Cleavage Eight-cell

stage

Cleavage Blastocoel

Cross section of blastula

Blastula

Gastrulation

Blastocoel Endoderm Ectoderm Archenteron

Cross section of gastrula

Blastopore 11


Video: Sea Urchin Embryonic Development (Time Lapse)

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!  Most animals have at least one larval stage

!  A larva is sexually immature and morphologically distinct from the adult; it eventually undergoes metamorphosis to become a juvenile

!  A juvenile resembles an adult, but is not yet sexually mature

13


!  Most animals, and only animals, have Hox genes that regulate the development of body form

!  Although the Hox family of genes has been highly conserved, it can produce a wide diversity of animal morphology

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Concept 32.2: The history of animals spans more than half a billion years !  More than 1.3 million animal species have been

named to date; far more are estimated to exist

!  The common ancestor of all living animals likely lived between 700 and 770 million years ago

15


Steps in the Origin of Multicellular Animals

!  Morphological and molecular evidence points to a group of protists called choanoflagellates as the closest living relatives to animals

!  The common ancestor may have resembled modern choanoflagellates

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Figure 32.3

Individual choanoflagellate

Choano- flagellates

OTHER EUKARYOTES Sponges

Other animals

Collar cell (choanocyte)

Anim

als

17


!  The origin of multicellularity requires the evolution of new ways for cells to adhere (attach) and signal (communicate) to each other

!  Molecular analysis has revealed similarities between genes coding for proteins involved in adherence and attachment in choanoflagellates and animals

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Figure 32.4

Choano- flagellate

Hydra

Fruit fly

Mouse

“CCD” domain (only found in animals)

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Neoproterozoic Era (1 Billion–542 Million Years Ago) !  Early members of the animal fossil record include

the Ediacaran biota, which dates back to about 560 million years ago

!  Early animal embryos and evidence of predation have also been found in Neoproterozoic rocks

20


Figure 32.5

1.5 cm

(a) Mawsonites spriggi

0.4 cm

(b) Spriggina floundersi

21


Figure 32.5a

1.5 cm

(a) Mawsonites spriggi

22


Figure 32.5b

0.4 cm

(b) Spriggina floundersi

23


Figure 32.6

Bore hole

0.1 mm

24


Paleozoic Era (542–251 Million Years Ago)

!  The Cambrian explosion (535 to 525 million years ago) marks the earliest fossil appearance of many major groups of living animals

!  Most of the fossils from the Cambrian explosion are of bilaterians, organisms that have the following traits:

!  Bilaterally symmetric form

!  Complete digestive tract

!  One-way digestive system 25


Figure 32.7

Hallucigenia fossil (530 mya)

1 cm

26


Figure 32.7a

27


Figure 32.7b

Hallucigenia fossil (530 mya) 1 cm

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!  There are several hypotheses regarding the cause of the Cambrian explosion and decline of Ediacaran biota

!  New predator-prey relationships

!  A rise in atmospheric oxygen

!  The evolution of the Hox gene complex

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!  Animal diversity continued to increase through the Paleozoic, but was punctuated by mass extinctions

!  Animals began to make an impact on land by 450 million years ago

!  Vertebrates made the transition to land around 365 million years ago

30


Mesozoic Era (251–65.5 Million Years Ago)

!  Coral reefs emerged, becoming important marine ecological niches for other organisms

!  The ancestors of plesiosaurs were reptiles that returned to the water

!  During the Mesozoic era, dinosaurs were the dominant terrestrial vertebrates

!  The first mammals emerged

!  Flowering plants and insects diversified

31


Cenozoic Era (65.5 Million Years Ago to the Present) !  The beginning of the Cenozoic era followed mass

extinctions of both terrestrial and marine animals

!  These extinctions included the large, nonflying dinosaurs and the marine reptiles

!  Mammals increased in size and exploited vacated ecological niches

!  The global climate cooled

32


Concept 32.3: Animals can be characterized by “body plans” !  Zoologists sometimes categorize animals

according to a body plan, a set of morphological and developmental traits

!  Some body plans have been conserved, while others have changed multiple times over the course of evolution

33


Symmetry

!  Animals can be categorized according to the symmetry of their bodies, or lack of it

!  Some animals have radial symmetry, with no front and back, or left and right

34


Figure 32.8

(a) Radial symmetry

Bilateral symmetry (b) 35


!  Two-sided symmetry is called bilateral symmetry

!  Bilaterally symmetrical animals have

!  A dorsal (top) side and a ventral (bottom) side

!  A right and left side

!  Anterior (front) and posterior (back) ends

!  Many also have sensory equipment, such as a brain, concentrated in their anterior end

36


!  Radial animals are often sessile or planktonic (drifting or weakly swimming)

!  Bilateral animals often move actively and have a central nervous system

37


Tissues

!  Animal body plans also vary according to the organization of the animal’s tissues

!  Tissues are collections of specialized cells isolated from other tissues by membranous layers

!  During development, three germ layers give rise to the tissues and organs of the animal embryo

38


!  Ectoderm is the germ layer covering the embryo’s surface

!  Endoderm is the innermost germ layer and lines the developing digestive tube, called the archenteron

39


!  Sponges and a few other groups lack true tissues

!  Diploblastic animals have ectoderm and endoderm

!  These include cnidarians and a few other groups

!  Triploblastic animals also have an intervening mesoderm layer; these include all bilaterians

!  These include flatworms, arthropods, vertebrates, and others

40


Body Cavities

!  Most triploblastic animals possess a body cavity

!  A true body cavity is called a coelom and is derived from mesoderm

!  Coelomates are animals that possess a true coelom

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Figure 32.9

(a) Coelomate

Key Ectoderm

Mesoderm

Endoderm

Coelom Body covering (from ectoderm)

Tissue layer lining coelom and suspending internal organs (from mesoderm) Digestive tract

(from endoderm)

Body covering (from ectoderm)

Muscle layer (from mesoderm)

Pseudo- coelom

Digestive tract (from endoderm)

(c) Acoelomate Body covering (from ectoderm)

Tissue- filled region (from mesoderm)

Wall of digestive cavity (from endoderm)

(b) Psuedocoelomate

42


Figure 32.9a

(a) Coelomate

Key Ectoderm Mesoderm Endoderm

Coelom Body covering (from ectoderm)

Tissue layer lining coelom and suspending internal organs (from mesoderm)


43


Figure 32.9b

(b) Pseudocoelomate


Body covering (from ectoderm)

Muscle layer (from mesoderm)

Pseudo- coelom


44


Figure 32.9c

(c) Acoelomate

Body covering (from ectoderm) Tissue-

filled region (from mesoderm)

Wall of digestive cavity (from endoderm)


45


!  A pseudocoelom is a body cavity derived from the mesoderm and endoderm

!  Triploblastic animals that possess a pseudocoelom are called pseudocoelomates

46


!  Triploblastic animals that lack a body cavity are called acoelomates

47


!  Terms such as coelomates and pseudocoelomates refer to organisms that have a similar body plan and belong to the same grade

!  A grade is a group whose members share key biological features

!  A grade is not necessarily a clade, an ancestor and all of its descendants

48


Protostome and Deuterostome Development

!  Based on early development, many animals can be categorized as having protostome development or deuterostome development

49


Cleavage

!  In protostome development, cleavage is spiral and determinate

!  In deuterostome development, cleavage is radial and indeterminate

!  With indeterminate cleavage, each cell in the early stages of cleavage retains the capacity to develop into a complete embryo

!  Indeterminate cleavage makes possible identical twins, and embryonic stem cells

50


Figure 32.10 Protostome development

(examples: molluscs, annelids)

Deuterostome development (examples: echinoderms,

chordates) (a) Cleavage


(b) Coelom formation

(c) Fate of the blastopore

Eight-cell stage Eight-cell stage

Spiral and determinate Radial and indeterminate

Coelom

Archenteron

Coelom Mesoderm Blastopore

Solid masses of mesoderm split and form coelom.

Folds of archenteron form coelom.

Blastopore Mesoderm

Anus

Digestive tube

Mouth Anus

Mouth

Mouth develops from blastopore. Anus develops from blastopore. 51


Figure 32.10a

Protostome development (examples: molluscs,

annelids)


chordates) (a) Cleavage Eight-cell stage

Spiral and determinate

Eight-cell stage

Radial and indeterminate

52


Figure 32.10b


annelids)


chordates) (b) Coelom

formation


Coelom

Archenteron

Coelom Blastopore Mesoderm Blastopore Mesoderm

Solid masses of mesoderm split and form coelom.

Folds of archenteron form coelom.

53


Figure 32.10c


annelids)


chordates) (c) Fate of the

blastopore


Anus

Mouth Mouth develops from blastopore.

Digestive tube

Anus

Mouth

Anus develops from blastopore.

54


Coelom Formation

!  In protostome development, the splitting of solid masses of mesoderm forms the coelom

!  In deuterostome development, the mesoderm buds from the wall of the archenteron to form the coelom

55


Fate of the Blastopore

!  The blastopore forms during gastrulation and connects the archenteron to the exterior of the gastrula

!  In protostome development, the blastopore becomes the mouth

!  In deuterostome development, the blastopore becomes the anus

56


Concept 32.4: Views of animal phylogeny continue to be shaped by new molecular and morphological data !  By 500 million years ago, most animal phyla with

members alive today were established

57


The Diversification of Animals

!  Zoologists recognize about three dozen animal phyla

!  Phylogenies now combine morphological, molecular, and fossil data

58


!  Five important points about the relationships among living animals are reflected in their phylogeny

1. All animals share a common ancestor

2. Sponges are basal animals

3. Eumetazoa (“true animals”) is a clade of animals with true tissues

4. Most animal phyla belong to the clade Bilateria

5. There are three major clades of bilaterian animals, all of which are invertebrates, animals that lack a backbone, except Chordata, which are classified as vertebrates because they have a backbone

59


Figure 32.11

ANCESTRAL PROTIST

Porifera

Ctenophora

Cnidaria

Acoela 770 million years ago

680 million years ago


Metazoa

Eumetazoa

Bilateria

Hemichordata

Echinodermata

Chordata

Platyhelminthes

Rotifera

Ectoprocta

Brachiopoda

Mollusca

Annelida

Nematoda

Arthropoda

Deuterostom

ia

Lophotrochozoa Ecdysozoa

60


Figure 32.11a

Porifera

Ctenophora

Cnidaria

Acoela

ANCESTRAL PROTIST




Metazoa

Eumetazoa

Bilateria

61


Figure 32.11b

Hemichordata

Echinodermata

Chordata

Platyhelminthes

Rotifera

Ectoprocta

Brachiopoda

Mollusca

Annelida

Nematoda

Arthropoda

Deuterostom

ia

Lophotrochozoa Ecdysozoa 62


!  The bilaterians are divided into three clades: Deuterostomia, Ecdysozoa, and Lophotrochozoa

!  Deuterostomia includes hemichordates (acorn worms), echinoderms (sea stars and relatives), and chordates

!  This clade includes both vertebrates and invertebrates

63


!  Ecdysozoa is a clade of invertebrates that shed their exoskeletons through a process called ecdysis

64


!  Lophotrochozoa is another clade of bilaterian invertebrates

!  Some lophotrochozoans have a feeding structure called a lophophore

!  Others go through a distinct developmental stage called the trochophore larva

65


Figure 32.12

Lophophore feeding structures of an ectoproct

(a)

Lophophore

Structure of a trochophore larva

(b)

Anus

Mouth

Apical tuft of cilia

66


Figure 32.12a

Lophophore feeding structures of an ectoproct

(a)

Lophophore

67


Future Directions in Animal Systematics

!  Systematics, like all fields of scientific research, is an ongoing, dynamic process of inquiry

!  Three outstanding questions are the focus of current research

1. Are sponges monophyletic?

2. Are ctenophores basal metazoans?

3. Are acoelomate flatworms basal bilaterians?

68


Figure 32.UN01

Animal Phylum Porifera

Platyhelminthes Cnidaria

Nematoda Echinodermata

Cephalochordata Arthropoda Urochordata

Mollusca Annelida

Vertebrata

i

1 2 3 4 5

7 6

8 9

10 11

5.8 35 2.5

26 38.6 33 59.1 25 50.8 58

147.5

No. of miRNAs (xi)

Sy �

Σ �

No. of Cell Types (yi)

25 30 34 38 45 68 73 77 83 94

172.5

Sx �

Σ � Σ �

69


Figure 32.UN02

535−525 mya: Cambrian explosion

560 mya: Ediacaran animals

365 mya: Early land

animals

Origin and diversification

of dinosaurs Diversification

of mammals Era

Neoproterozoic Paleozoic Mesozoic Ceno- zoic

1,000 542 251 65.5 0 Millions of years ago (mya)

70


Figure 32.UN03

Porifera (basal animals)

Ctenophora

Cnidaria

Acoela (basal bilaterians)

Deuterostomia

Lophotrochozoa

Ecdysozoa

True tissues

Bilateral symmetry

Three germ layers

Metazoa Eum

etazoa

Bilateria (m

ost animals)

71


Figure 32.UN04

Blastopore Fate Phyla

Protostomy (P)

Deuterostomy (D)

Neither (N)

Source: A. Hejnol and M. Martindale, The mouth, the anus, and the blastopore�open questions about questionable openings. In Animal Evolu- tion: Genomes, Fossils and Trees, eds. D. T. J. Littlewood and M. J. Telford, Oxford University Press, pp. 33–40 (2009).

Platyhelminthes, Rotifera, Nematoda; most Mollusca, most Annelida; few Arthropoda Echinodermata, Chordata; most Arthropoda; few Mollusca, few Annelida Acoela

72


Figure 32.UN05

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reece •urry• cain • wasserman •minorsky• jackson 32...campbell biology reece •urry•...

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