17 lecture presentation

© 2010 Pearson Education, Inc.

Chapter 17


What Is an Animal?• Animals are:

– Eukaryotic

– Multicellular

– Heterotrophic organisms that obtain nutrients by ingestion

– Able to digest their food within their bodies

• Animal cells lack the cell walls that provide strong support in the bodies of plants and fungi.


• Most animals have:

– Muscle cells

– Nerve cells that control the muscles


• Most animals:

– Are diploid

– Reproduce sexually

– Proceed through a series of typically similar developmental stages

MEIOSIS

Sperm

Egg

Adult

Key

FERTILIZATION

MITOSIS

Eight-cell stage

Internal sac

Digestive tract

Larva

METAMORPHOSIS

Haploid (n)

Diploid (2n)

Outer cell layer(ectoderm)

Later gastrula(cross section)

Future middlelayer of cells(mesoderm)

Inner cell layer(endoderm)

Early gastrula(cross section)

Blastula(cross section)

Zygote(fertilized egg)

Figure 17.2-8


Animal Phylogeny• Biologists categorize animals by:

– General features of body structure

– More recently, using genetic data

Ancestralprotist

No true tissues

Radial symmetry

Tissues

Bilateral symmetry

Sponges

Cnidarians

Molluscs

Flatworms

Annelids

Roundworms

Arthropods

Echinoderms

Chordates

Figure 17.5


• A second major evolutionary split is based on body symmetry.

– Radial symmetry refers to animals that are identical all around a central axis.

– Bilateral symmetry exists where there is only one way to split the animal into equal halves.

Radial symmetry. Parts radiate from the center, so any slicethrough the central axis divides into mirror images.

Bilateral symmetry. Only one slice can divide left and rightsides into mirror-image halves.

Figure 17.6


• Animals also vary according to the presence and type of body cavity, a fluid-filled space separating the digestive tract from the outer body wall.


• There are differences in how the body cavity forms.

– If the body cavity is not completely lined by tissue derived from mesoderm, it is a pseudocoelom.

– A true coelom is completely lined by tissue derived from mesoderm.

(a) No body cavity

(b) Pseudocoelom

(c) True coelom

Body covering(from ectoderm)

Tissue-filledregion (frommesoderm)



Musclelayer (frommesoderm)

Tissue layer liningcoelom andsuspendinginternal organs(from mesoderm)

Digestive tract(from endoderm)



Pseudocoelom

Coelom

Figure 17.7

(a) No body cavity: for example, flatworm


Tissue-filledregion (frommesoderm)


Figure 17.7a

(b) Pseudocoelom: a body cavity only partiallylined by the mesoderm, the middle tissue layer;for example, roundworm


Musclelayer (frommesoderm)


Pseudocoelom

Figure 17.7b

(c) True coelom: a fluid-filled body cavity completelylined by mesoderm, for example, annelid


Tissue layer liningcoelom andsuspendinginternal organs(from mesoderm)Digestive tract

(from endoderm)

Coelom

Figure 17.7c


MAJOR INVERTEBRATE PHYLA• Invertebrates:

– Are animals without backbones

– Represent 95% of the animal kingdom


Sponges• Sponges

• Sponges include sessile animals that lack true tissues and that were once believed to be plants.


• The body of a sponge resembles a sac perforated with holes.

• Choanocyte cells draw water through the walls of the sponge where food is collected.

Choanocyte(feeding cell)

Waterflow

Skeletalfiber

Centralcavity

Choanocytein contactwith anamoebocyte

Amoebocyte

Flagella

Pores

Figure 17.8

Waterflow

Skeletalfiber

Centralcavity

Choanocytein contactwith anamoebocyte

Amoebocyte

Flagella

Pores

Choanocyte(feeding cell)

Figure 17.8a


Cnidarians• Cnidarians (phylum Cnidaria) are characterized by:

– The presence of body tissues

– Radial symmetry

– Tentacles with stinging cells


• The basic body plan of a cnidarian is a sac with a gastrovascular cavity, a central digestive compartment with only one opening.

• The body plan has two variations:

– The sessile polyp

– The floating medusa

Mouth/anus

Tentacle

Polyp form

Gastrovascularcavity

Coral Hydra

Sea anemone


Mouth/anusTentacle

Medusa form

JellyFigure 17.9

Mouth/anus

Tentacle

Polyp form


Coral Hydra

Sea anemone

Figure 17.9a

Mouth/anus

Tentacle

Polyp form


Figure 17.9aa

CoralFigure 17.9ab

Sea anemoneFigure 17.9ac

HydraFigure 17.9ad


Mouth/anusTentacle

Medusa form

Jelly

Figure 17.9b


Mouth/anus

Tentacle

Medusa formFigure 17.9ba

Jelly

Figure 17.9bb


• Cnidarians are carnivores that use tentacles, armed with cnidocytes (“stinging cells”), to capture prey.

Tentacle

Trigger

Capsule

Cnidocyte

Dischargeof thread

Prey

Coiledthread

Figure 17.10


Molluscs• Molluscs (phylum Mollusca) are represented by soft-bodied

animals, usually protected by a hard shell.

• Many molluscs feed by using a file-like organ called a radula to scrape up food.


• The body of a mollusc has three main parts:

– A muscular foot used for movement

– A visceral mass housing most of the internal organs

– A mantle, which secretes the shell if present

Visceral mass

Reproductiveorgans

Digestivetract

Mantlecavity

Nervecords

Digestivetract

Coelom

Radula

Radula

Kidney Heart

Shell

Mouth

Mouth

Anus

Gill

Foot

Mantle

Figure 17.11


• The three major groups of molluscs are:

– Gastropods, protected by a single, spiraled shell

Snail (spiraled shell)

Figure 17.12aa

Sea slug (no shell)

Figure 17.12ab


– Bivalves, with a shell divided into two halves hinged together

Bivalves(hinged shell)

ScallopFigure 17.12b

Octopus

Figure 17.12ca

Squid

Figure 17.12cb

Gastropods Bivalves(hinged shell)

Cephalopods(large brain and tentacles)

Snail (spiraled shell)

Sea slug (no shell)

Scallop Octopus Squid

MAJOR GROUPS OF MOLLUSCS

Figure 17.12


Flatworms• Flatworms (phylum Platyhelminthes) are the simplest bilateral

animals.

• Flatworms include forms that are:

– Parasites or

– Free-living in marine, freshwater, or damp habitats

Head

Sucker

Reproductive unitwith skin removed

Tapeworm

Figure 17.13ba

Blood fluke

Figure 17.13c


• The gastrovascular cavity of flatworms

– Is highly branched

– Provides an extensive surface area for absorption of nutrients

Digestive tract(gastrovascularcavity)

Nerve cords

Mouth

Eyespots (detect light)

Nervous tissue clusters(simple brain)

Planarian

Bilateral symmetry

Figure 17.13a

Digestive tract(gastrovascularcavity) Nerve cords

Mouth

Eyespots(detect light)

Nervous tissueclusters(simple brain)

Planarian Bilateral symmetry

Blood fluke

Head Hooks

Suckers

Reproductive unitwith skin removed

Tapeworm

Figure 17.13


Annelids• Annelids (phylum Annelida) have:

– Body segmentation, a subdivision of the body along its length into a series of repeated parts

– A coelom

– A complete digestive tract with

– Two openings, a mouth and anus

– One-way movement of food

Mouth

Brain

Coelom

Nerve cord

Blood vesselsWaste disposal organ

Anus

Accessoryhearts

Mainheart

Digestivetract

Segmentwalls

Figure 17.15


• The three main groups of annelids are:

– Earthworms, which eat their way through soil

– Polychaetes, marine worms with segmental appendages for movement and gas exchange

– Leeches, typically free-living carnivores but with some bloodsucking forms

Video: Earthworm Locomotion

Earthworms

Giant Australian earthwormFigure 17.14a

Polychaetes

Christmas tree worm

Figure 17.14b

Leeches

European freshwater leechFigure 17.14c


Roundworms• Roundworms (phylum Nematoda) are:

– Cylindrical in shape, tapered at both ends

– The most diverse and widespread of all animals

• Roundworms (also called nematodes) are:

– Important decomposers

– Dangerous parasites in plants, humans, and other animals

Video: C. elegans Embryo Development (time lapse)

Video: C. elegans Crawling

(a) A free-living roundwormFigure 17.16a

(b) Parasitic roundworms in porkFigure 17.16b

(c) Canine heart infected withparasitic roundworms

Figure 17.16c


Arthropods• Arthropods (phylum Arthropoda) are named for their jointed

appendages.

• There are about one million arthropod species identified, mostly insects.

• Arthropods are a very diverse and successful group, occurring in nearly all habitats in the biosphere.

• There are four main groups of arthropods.

MAJOR GROUPS OF ARTHROPODS

Arachnids

Crustaceans

Millipedes and Centipedes

Insects

Figure 17.17


General Characteristics of Arthropods

• Arthropods are segmented animals with specialized segments and appendages for an efficient division of labor among body regions.


• The body of arthropods is completely covered by an exoskeleton, an external skeleton that provides:

– Protection

– Points of attachment for the muscles that move appendages

Video: Lobster Mouth Parts


• Arachnids:

– Live on land

– Usually have four pairs of walking legs and a specialized pair of feeding appendages

– Include spiders, scorpions, ticks, and mites

Arachnids

Two feedingappendages

Leg (four pairs)

Black widow spider Wood tick

Dust miteScorpion

Figure 17.19


Leg (four pairs)

Tarantula spider (an arachnid)Figure 17.19a

ScorpionFigure 17.19b

Black widow spider

Figure 17.19c

Dust miteFigure 17.19d

Wood tick

Figure 17.19e


• Crustaceans:

– Are nearly all aquatic

– Have multiple pairs of specialized appendages

– Include crabs, lobsters, crayfish, shrimps, and barnacles

Crustaceans

AbdomenCephalothorax

(head and thorax)

Swimmingappendage

Antenna(sensory reception)

Eyes onmovable stalks

Mouthparts (feeding)

Walking leg

Walking legs

Figure 17.18

Two feedingappendages Leg (three or more pairs)

Antennae

BarnaclesCrayfish

Pill bugShrimp

Crab

Figure 17.20


Leg (three or more pairs)

Antennae

Crab (a crustacean)

Figure 17.20a

Crab

Figure 17.20b

Shrimp

Figure 17.20c

Pill bug

Figure 17.20d

Crayfish

Figure 17.20e

Barnacles

Figure 17.20f


• Millipedes and centipedes have similar segments over most of the body.

• Millipedes:

– Eat decaying plant matter

– Have two pairs of short legs per body segment

• Centipedes:

– Are terrestrial carnivores with poison claws

– Have one pair of short legs per body segment

Millipedes and Centipedes

One pair of legs per segment

Two pairs of legsper segment

Millipede Centipede

Figure 17.21

Two pairs of legsper segment

MillipedeFigure 17.21a

One pair of legs per segment

CentipedeFigure 17.21b


• Insects typically have a three-part body:

– Head

– Thorax

– Abdomen

Insect Anatomy


• The insect head usually bears:

– A pair of sensory antennae

– A pair of eyes

• The mouthparts are adapted for particular kinds of eating.

• Flight is one key to the great success of insects.

Antenna

Head Thorax Abdomen

Eye

Mouthparts

Figure 17.22


• Insects outnumber all other forms of life combined.

• Insects live in:

– Almost every terrestrial habitat

– Freshwater

– The air

Insect Diversity

Banded OrangeHeliconian

PrayingmantisGiraffe weevil

Yellow jacket wasp Leaf beetle

Leaf roller

Peacock katydid

Longhorn beetleFigure 17.23

Peacock katydidFigure 17.23a

Banded Orange HeliconianFigure 17.23b

Giraffe weevilFigure 17.23c

Yellow jacket waspFigure 17.23d

Leaf beetle

Figure 17.23e

Longhorn beetleFigure 17.23f

Praying mantisFigure 17.23g

Leaf rollerFigure 17.23h


• Many insects undergo metamorphosis in their development.

• Young insects may:

– Appear to be smaller forms of the adult or

– Change from a larval form to something much different as an adult

Video: Butterfly Emerging

The larva (caterpillar) spendsits time eating and growing,molting as it grows.

After several molts, thelarva becomes a pupaencased in a cocoon.

Within the pupa, the larval organs breakdown and adult organs develop fromcells that were dormant in the larva.

Finally, the adult emergesfrom the cocoon.

The butterfly flies off and reproduces, nourished mainlyby calories stored when it was a caterpillar.

Figure 17.24-5

Monarch butterflies

Figure 17.24a


Echinoderms• Echinoderms (phylum Echinodermata):

– Lack body segments

– Typically show radial symmetry as adults but bilateral symmetry as larvae

– Have an endoskeleton

– Have a water vascular system that facilitates movement and gas exchange

• Echinoderms are a very diverse group.

Video: Echinoderm Tube Feet

Sea star

Sea urchin

Sea cucumber Sand dollar

Tube feet

Figure 17.25

Sea star

Figure 17.25a

Sea star Figure 17.25aa

Sea star Figure 17.25ab

Sea starsFigure 17.25ac

Sea urchin

Tube feet

Figure 17.25b

Sea cucumber

Figure 17.25c

Sand dollarFigure 17.25d


VERTEBRATE EVOLUTION AND DIVERSITY

• Vertebrates have unique endoskeletons composed of:

– A cranium (skull)

– A backbone made of a series of bones called vertebrae

Vertebra

Cranium(protects brain)

Figure 17.26


Characteristics of Chordates• Chordates (phylum Chordata) all share four key features that

appear in the embryo and sometimes the adult:

– A dorsal, hollow nerve cord

– A notochord

– Pharyngeal slits

– A post-anal tail

Muscle segments

Notochord

Dorsal,

hollow

nerve cord

Pharyngeal

slits

Brain

Mouth

Anus

Post-anal

tail

Figure 17.27


• Another chordate characteristic is body segmentation, apparent in the:

– Backbone of vertebrates

– Segmental muscles of all chordates


• Chordates consists of three groups of invertebrates:

– Lancelets are bladelike animals without a cranium.

– Tunicates, or sea squirts, also lack a cranium.

– Hagfishes are eel-like forms that have a cranium.

• All other chordates are vertebrates.

Mouth

Tail

Lancelet Tunicates

Figure 17.28

Mouth

Tail

LanceletFigure 17.28a

Tunicates Figure 17.28b


THE HUMAN ANCESTRY• Humans are primates, the mammalian group that also includes:

– Lorises

– Pottos

– Lemurs

– Tarsiers

– Monkeys

– Apes

Ancestralprimate

Lemurs, lorises,and pottos

Tarsiers

New World monkeys

Old World monkeys

Gibbons

Orangutans

Gorillas

Chimpanzees

Humans

An

thro

po

ids

Mo

nk

ey

sA

pe

s

Figure 17.36


• Primates evolved from insect-eating mammals during the late Cretaceous period.

The Evolution of Primates


• Primates are distinguished by characteristics that were shaped by the demands of living in trees. These characteristics include:

– Limber shoulder joints

– Eyes in front of the face

– Excellent eye-hand coordination

– Extensive parental care


• Taxonomists divide the primates into three main groups.


• The first group of primates includes:

– Lorises

– Pottos

– Lemurs

Ring-tailed lemurFigure 17.37a


• Tarsiers form the second group.

TarsierFigure 17.37b


• The third group, anthropoids, includes:

– Monkeys

Patas monkey (Old World monkey)Figure 17.37d

Black spider monkey(New World monkey)

Figure 17.37c


– Hominoids, the ape relatives of humans

Video: Gibbons Brachiating

Video: Chimp Cracking Nut

Video: Chimp Agonistic Behavior

Gibbon (ape)Figure 17.37e

Gorilla (ape)Figure 17.37g

Orangutan (ape)Figure 17.37f

Chimpanzee (ape)Figure 17.37h


– And humans

HumanFigure 17.37i

Ring-tailedlemur

Tarsier

Black spider monkey(New World monkey)

Patas monkey (Old World monkey)

Gorilla (ape)

Gibbon (ape)

Chimpanzee (ape)

Orangutan (ape)

HumanFigure 17.37


The Emergence of Humankind• Humans and chimpanzees have shared a common African

ancestry for all but the last 5–7 million years.


Some Common Misconceptions

• Chimpanzees and humans represent two divergent branches of the anthropoid tree that each evolved from a common, less specialized ancestor.

• Our ancestors were not chimpanzees or any other modern apes.


• Human evolution is not a ladder with a parade of fossil hominids (members of the human family) leading directly to modern humans.

• Instead, human evolution is more like a multibranched bush than a ladder.

• At times in hominid history, several different human species coexisted.

Ardipithecusramidus

Australopithecusafarensis

Australopithecusafricanus

Paranthropusrobustus

Paranthropusboisei

Homoneanderthalensis

Homosapiens

Homohabilis

Homo erectus

?M

illi

on

s o

f y

ea

rs a

go

6.0

5.0

5.5

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

Figure 17.38


• Upright posture and an enlarged brain appeared at separate times during human evolution.

• Different human features evolved at different rates.


Australopithecus and the Antiquity of Bipedalism

• Before there was the genus Homo, several hominid species of the genus Australopithecus walked the African savanna.

• Fossil evidence pushes bipedalism in A. afarensis back to at least 4 million years ago.

(a) Australopithecusafarensis skeleton

(b) Ancient footprints (c) Model of anAustralopithecusafarensis male

Figure 17.39

(a) Australopithecusafarensis skeleton

Figure 17.39a

(b) Ancient footprintsFigure 17.39b


Homo Habilis and the Evolution of Inventive Minds

• Homo habilis, “handy-man”:

– Had a larger brain, intermediate in size between Australopithecus and modern humans

– Walked upright

– Made stone tools that enhanced hunting, gathering, and scavenging on the African savanna

Homo Erectus and the Global Dispersal of Humanity

• Homo erectus was the first species to extend humanity’s range from Africa to other continents.

• The global dispersal began about 1.8 million years ago.



• Homo erectus:

– Was taller than H. habilis

– Had a larger brain

– Gave rise to Neanderthals


The Origin and Dispersal of Homo Sapiens

• The oldest known fossils of our own species, Homo sapiens:

– Were discovered in Ethiopia

– Date from 160,000 to 195,000 years ago


• DNA studies strongly suggest that all living humans can trace their ancestry back to a single African Homo sapiens woman who lived 160,000 to 200,000 years ago.


• Fossil evidence suggests that our species emerged from Africa in one or more waves.

• The oldest fossils of H. sapiens outside of Africa are 50,000 years old.

• The oldest fossils of humans in the New World are uncertain, but are at least 15,000 years old.


Cultural Evolution

• Culture is the social transmission of accumulated knowledge, customs, beliefs, and art over generations.

• Culture is primarily transmitted by language.


• Cultural evolution has had three major stages.

– First, nomads who were hunter-gatherers:

– Made tools

– Organized communal activities

– Divided labor

– Created art

Figure 17.41

Figure 17.41a

Figure 17.41b

Figure 17.41c


– The second main stage of cultural evolution was the development of agriculture in Africa, Eurasia, and the Americas, about 10,000 to 15,000 years ago.

– The third stage was the Industrial Revolution, which began in the 1700s.


• The global consequences of human evolution have been enormous. Humans can:

– Defy our physical limitation

– Shortcut biological evolution

– Change the environment to meet our needs

Figure 17.42

Figure 17.43

Ancestralprotist

True tissues

Bilateral symmetry

Sponges

Cnidarians

Molluscs

Flatworms

Annelids

Roundworms

Arthropods

Echinoderms

Chordates

Figure 17.UN15

Radial symmetry Bilateral symmetry

Figure 17.UN18

Gastropods Bivalves Cephalopods

MOLLUSCS

Figure 17.UN19

Arachnids

ARTHROPODS

Crustaceans InsectsMillipedesand Centipedes

Figure 17.UN20

Monotremes

MAMMALS

Marsupials Eutherians

Figure 17.UN21

Science

17 lecture presentation