Download Chapter 17 - Fullfrontalanatomy.com

The Evolution of Animals
The Origins of Animal Diversity
Major invertebrate Phyla
Vertebrate Evolution and Diversity
The Human Ancestry
© 2010 Pearson Education, Inc.
Figure 17.00
– Some scientists think that these bones represent
pygmies of a previously unknown human species,
named Homo floresiensis.
– Other scientists suggest that the bones are from
diseased Homo sapiens.
© 2010 Pearson Education, Inc.
THE ORIGINS OF ANIMAL
DIVERSITY
– Animal life began in Precambrian seas with the
evolution of multicellular creatures that ate other
organisms.
© 2010 Pearson Education, Inc.
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.
© 2010 Pearson Education, Inc.
© 2010 Pearson Education, Inc.
Figure 17.1
– Most animals have:
•
•
•
•
•
Muscle cells
Nerve cells that control the muscles
Are diploid
Reproduce sexually
Proceed through a series of typically similar
developmental stages
© 2010 Pearson Education, Inc.
Sperm
FERTILIZATION
MEIOSIS
Egg
MITOSIS
Zygote
(fertilized egg)
Eight-cell stage
Adult
METAMORPHOSIS
Blastula
(cross section)
Digestive tract
Outer cell layer
(ectoderm)
Larva
Inner cell layer
(endoderm)
Internal sac
Early gastrula
(cross section)
Later gastrula Future middle
(cross section) layer of cells
(mesoderm)
Key
Haploid (n)
Diploid (2n)
Figure 17.2-8
Early Animals and the Cambrian
Explosion
– Animals probably evolved from a colonial
flagellated protist that lived in Precambrian seas
about 600–700 million years ago.
© 2010 Pearson Education, Inc.
Digestive
cavity
Reproductive cells
Figure 17.3-5
– At the beginning of the Cambrian period, 542
million years ago, animals underwent a rapid
diversification.
– During a span of about 15 million years:
• All major animal body plans we see today evolved
• Many of these animals seem bizarre
© 2010 Pearson Education, Inc.
Figure 17.4
– What ignited the Cambrian explosion?
• One hypothesis emphasizes increasingly complex
predator-prey relationships that led to diverse
adaptations to feed, move, and provide protection.
• Another hypothesis, studying evolution and
development, called evo-devo, focuses on the
evolution of genes that control the development of
animal forms.
© 2010 Pearson Education, Inc.
Animal Phylogeny
– Biologists categorize animals by:
• General features of body structure
• More recently, using genetic data
– One major branch point distinguishes sponges
from all other animals because, unlike more
complex animals, sponges lack true tissues.
© 2010 Pearson Education, Inc.
Sponges
No true tissues
Cnidarians
Radial symmetry
Ancestral
protist
Molluscs
Flatworms
Tissues
Annelids
Roundworms
Arthropods
Bilateral symmetry
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.
© 2010 Pearson Education, Inc.
Radial symmetry. Parts radiate from the center, so any slice
through the central axis divides into mirror images.
Bilateral symmetry. Only one slice can divide left and right
sides 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.
© 2010 Pearson Education, Inc.
Body covering
(from ectoderm)
(a) No body cavity
Tissue-filled
region (from
mesoderm)
Digestive tract
(from endoderm)
Body covering
(from ectoderm)
(b) Pseudocoelom
Muscle
layer (from
mesoderm)
Pseudocoelom
Digestive tract
(from endoderm)
(c) True coelom
Coelom
Digestive tract
(from endoderm)
Body covering
(from ectoderm)
Tissue layer lining
coelom and
suspending
internal organs
(from mesoderm)
Figure 17.7
MAJOR INVERTEBRATE PHYLA
– Invertebrates:
• Are animals without backbones
• Represent 95% of the animal kingdom
© 2010 Pearson Education, Inc.
Sponges
– Sponges represent multiple phyla.
– 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.
© 2010 Pearson Education, Inc.
Pores
Amoebocyte
Skeletal
fiber
Central
cavity
Choanocyte
(feeding cell)
Water
flow
Flagella
Choanocyte
in contact
with an
amoebocyte
Figure 17.8
Cnidarians
– Cnidarians (phylum Cnidaria) are characterized
by:
• The presence of “true” 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 – not able to move about
• The floating medusa – the “mobile stage”
– Cnidarians are carnivores that use tentacles, armed with cnidocytes
(“stinging cells”), to capture prey.
© 2010 Pearson Education, Inc.
Mouth/anus
Tentacle
Gastrovascular
cavity
Polyp form
Coral
Hydra
Sea anemone
Gastrovascular
cavity
Mouth/anus
Tentacle
Medusa form
Jelly
Figure 17.9
Tentacle
Coiled Capsule
thread
Trigger
Discharge
of thread
Prey
Cnidocyte
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
– The three major groups of molluscs are:
• Gastropods, protected by a single, spiraled shell
• Bivalves, with a shell divided into two halves hinged together
• And cephalopods
– Typically lacking an external shell
– Built for speed and agility
© 2010 Pearson Education, Inc.
Visceral mass
Coelom
Kidney
Heart
Reproductive
organs
Digestive
tract
Shell
Mantle
Mantle
cavity
Radula
Anus
Gill
Mouth
Foot
Nerve
cords
Digestive
tract
Radula
Mouth
Figure 17.11
Gastropods
Snail (spiraled shell)
Sea slug (no shell)
Figure 17.12a
Bivalves
(hinged shell)
Scallop
Figure 17.12b
Cephalopods
(large brain and tentacles)
Octopus
Squid
Figure 17.12c
Flatworms
– Flatworms (phylum Platyhelminthes) are the
simplest bilateral animals.
– Have “true” tissues
– Flatworms include forms that are:
• Parasites or
• Free-living in marine, freshwater, or damp habitats
– The gastrovascular cavity of flatworms
• Is highly branched
• Provides an extensive surface area for absorption of
nutrients
© 2010 Pearson Education, Inc.
Digestive tract
(gastrovascular
cavity)
Nerve cords
Mouth
Eyespots (detect light)
Nervous tissue clusters
(simple brain)
Planarian
Bilateral symmetry
Figure 17.13a
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
– 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
© 2010 Pearson Education, Inc.
Anus
Brain
Main
heart
Coelom
Digestive
tract
Segment
walls
Mouth
Accessory
hearts
Nerve cord
Waste disposal organ
Blood vessels
Figure 17.15
MAJOR GROUPS OF ANNELIDS
Earthworms
Polychaetes
Leeches
Giant Australian earthworm
Christmas tree worm
European freshwater leech
Figure 17.14
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
© 2010 Pearson Education, Inc.
(a) A free-living
roundworm
(b) Parasitic
roundworms in pork
(c) Canine heart
Infected with parasitic
roundworms
Figure 17.16
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.
Insects, crustaceans, arachnids (spiders) and
millipedes and centipedes
– Arthropods are segmented animals with
specialized segments and appendages for an
efficient division of labor among body regions.
This allows for their great success as a phylum.
© 2010 Pearson Education, Inc.
MAJOR GROUPS OF ARTHROPODS
Arachnids
Crustaceans
Millipedes and Centipedes
Insects
Figure 17.17
– 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
© 2010 Pearson Education, Inc.
an arthropod of the large, mainly aquatic group Crustacea,
such as a crab, lobster, shrimp, or barnacle.
Abdomen
Cephalothorax
(head and thorax)
Antenna
(sensory reception)
Eyes on
movable stalks
Mouthparts (feeding)
Walking leg
Swimming
appendage
Walking legs
Figure 17.18
Arachnids
– Arachnids:
• Live on land
• Usually have four pairs of walking legs and a
specialized pair of feeding appendages
• Include spiders, scorpions, ticks, and mites
© 2010 Pearson Education, Inc.
Two feeding
appendages
Leg (four pairs)
Scorpion
Black widow spider
Dust mite
Wood tick
Figure 17.19
Crustaceans
– Crustaceans:
• Are nearly all aquatic
• Have multiple pairs of specialized appendages
• Include crabs, lobsters, crayfish, shrimps, and
barnacles
© 2010 Pearson Education, Inc.
Two feeding
appendages
Leg (three or more pairs)
Antennae
Crab
Shrimp
Crayfish
Pill bug
Barnacles
Figure 17.20
Millipedes and Centipedes
– 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
© 2010 Pearson Education, Inc.
One pair of legs per segment
Two pairs of legs
per segment
Millipede
Centipede
Figure 17.21
Insect Anatomy
– Insects typically have a three-part body:
• Head
• Thorax
• Abdomen
– 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.
© 2010 Pearson Education, Inc.
Head Thorax
Abdomen
Antenna
Eye
Mouthparts
Figure 17.22
Insect Diversity
– Insects outnumber all other forms of life
combined.
– Insects live in:
• Almost every terrestrial habitat
• Freshwater
• The air
© 2010 Pearson Education, Inc.
Leaf roller
Banded Orange
Heliconian
Giraffe weevil
Peacock katydid
Praying
mantis
Yellow jacket wasp Leaf beetle
Longhorn beetle
Figure 17.23
– 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
© 2010 Pearson Education, Inc.
The larva (caterpillar) spends
its time eating and growing,
molting as it grows.
After several molts, the
larva becomes a pupa
encased in a cocoon.
Finally, the adult emerges
from the cocoon.
Within the pupa, the larval organs break
down and adult organs develop from
cells that were dormant in the larva.
The butterfly flies off and reproduces, nourished mainly
by 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.
© 2010 Pearson Education, Inc.
Sea star
Tube feet
Sea urchin
Sea cucumber
Sand dollar
Figure 17.25
VERTEBRATE EVOLUTION AND
DIVERSITY
– Vertebrates have unique endoskeletons
composed of:
• A cranium (skull)
• A backbone made of a series of bones called
vertebrae
© 2010 Pearson Education, Inc.
Cranium
(protects brain)
Vertebra
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
• A lancelet is an invertebrate chordate
© 2010 Pearson Education, Inc.
Dorsal,
hollow
Notochord
nerve cord
Brain
Muscle segments
Mouth
Anus
Post-anal
tail
Pharyngeal
slits
Figure 17.27
– Another chordate characteristic is body
segmentation, apparent in the:
• Backbone of vertebrates
• Segmental muscles of all chordates
© 2010 Pearson Education, Inc.
– 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.
© 2010 Pearson Education, Inc.
Mouth
Tail
Lancelet
Tunicates
Figure 17.28
– An overview of chordate and vertebrate
evolution
© 2010 Pearson Education, Inc.
Ancestral
chordate
Chordates
Tunicates
Lancelets
Hagfishes
Vertebrates
Lampreys
Cartilaginous
fishes
Bony fishes
Mammals
Amniotes
Reptiles
Tetrapods
Amphibians
Figure 17.29
Fishes
– The first vertebrates were aquatic and probably
evolved during the early Cambrian period, about
542 million years ago. They:
• Lacked jaws
• Are represented today by hagfishes
© 2010 Pearson Education, Inc.
(a) Hagfish (inset: slime)
Figure 17.30a
– Lampreys:
• Are vertebrates
• Have a cranium
• But lack jaws
© 2010 Pearson Education, Inc.
(b) Lamprey (inset: mouth)
Figure 17.30b
– The two major groups of living fishes are the:
• Cartilaginous fishes (sharks and rays) with a flexible
skeleton made of cartilage
© 2010 Pearson Education, Inc.
Lateral line
(c) Shark, a cartilaginous fish
Figure 17.30c
• And bony fishes with a skeleton reinforced by
hard calcium salts
– Bony fishes include:
• Ray-finned fishes
• Lungfishes
• Lobe-finned fishes
© 2010 Pearson Education, Inc.
Operculum
Lateral line
(d) Bony fish
Figure 17.30d
(a) Hagfish
(inset: slime)
(b) Lamprey
(inset: mouth)
Operculum
(c) Shark, a
cartilaginous fish
Lateral line
(d) Bony fish
Figure 17.30
– Cartilaginous and bony fishes have a lateral
line system that detects minor vibrations in the
water.
– To provide lift off the bottom:
• Cartilaginous fish must swim but
• Bony fish have swim bladders, gas-filled sacs that
make them buoyant
© 2010 Pearson Education, Inc.
Amphibians
– Amphibians:
• Exhibit a mixture of aquatic and terrestrial adaptations
• Usually need water to reproduce
• Typically undergo metamorphosis from an aquatic
larva to a terrestrial adult
© 2010 Pearson Education, Inc.
(a) Tadpole and adult golden palm tree frog
Red-eyed tree frog
Texas barred tiger salamander
(b) Frogs and salamanders: the two major groups of amphibians
Figure 17.31
– Amphibians:
• Were the first vertebrates to colonize land
• Descended from fishes that had lungs and fins with
muscles
© 2010 Pearson Education, Inc.
Lobe-finned fish
Early amphibian
Figure 17.32
– Terrestrial vertebrates are collectively called
tetrapods, which means “four feet.”
– Tetrapods include:
• Amphibians
• Reptiles
• Mammals
© 2010 Pearson Education, Inc.
Reptiles
– Reptiles (including birds) and mammals are
amniotes, which produce amniotic eggs that
consist of a fluid-filled shell inside of which the
embryo develops.
© 2010 Pearson Education, Inc.
– Reptiles include:
•
•
•
•
•
•
Snakes
Lizards
Turtles
Crocodiles
Alligators
Birds
© 2010 Pearson Education, Inc.
– Reptile adaptations to living on land include:
• Amniotic eggs
• Scaled, waterproof skin
Video: Galápagos Tortoise
© 2010 Pearson Education, Inc.
Dinosaur
Snake
Lizard
Crocodile
Birds
Turtle
Figure 17.33
– Nonbird reptiles are ectotherms, sometimes
referred to as “cold-blooded,” which means that
they obtain their body heat from the
environment.
– A nonbird reptile can survive on less than 10%
of the calories required by a bird or mammal of
equivalent size.
– Dinosaurs were the largest animals ever to live
on land.
© 2010 Pearson Education, Inc.
Birds
– Recent genetic evidence shows that birds
evolved from a lineage of small, two-legged
dinosaurs during the great reptilian radiation of
the Mesozoic era.
– Birds have many adaptations that make them
lighter in flight:
• Honeycombed bones
• One instead of two ovaries
• A beak instead of teeth
– Unlike other reptiles, birds are endotherms,
maintaining a warmer and steady body
temperature.
© 2010 Pearson Education, Inc.
– Birds wings adapted for flight are airfoils,
powered by breast muscles anchored to a keellike breastbone.
© 2010 Pearson Education, Inc.
Lower air pressure
Higher air pressure
Figure 17.34
Mammals
– The first true mammals:
• Arose about 200 million years ago
• Were probably small, nocturnal insect-eaters
– Most mammals are terrestrial although dolphins,
porpoises, and whales are totally aquatic.
– Mammalian hallmarks are:
• Hair
• Mammary glands that produce milk, which nourishes
the young
– There are three major groups of mammals:
• Monotremes, egg-laying mammals
• Marsupials, pouched mammals with a placenta
• And eutherians, placental mammals
© 2010 Pearson Education, Inc.
MAJOR GROUPS OF MAMMALS
Monotremes
(hatched from eggs)
Echidna adult
and egg
Marsupials
(embryonic at birth)
Eutherians
(fully developed at birth)
Kangaroo newborn and mother
Wildebeest newborn
and mother
Figure 17.35
– Eutherian placentas provide more intimate and
long-lasting association between the mother and
her developing young than do marsupial
placentas.
© 2010 Pearson Education, Inc.
THE HUMAN ANCESTRY
– Humans are primates, the mammalian group
that also includes:
•
•
•
•
•
•
Lorises
Pottos
Lemurs
Tarsiers
Monkeys
Apes
© 2010 Pearson Education, Inc.
Lemurs, lorises,
and pottos
Ancestral
primate
Tarsiers
Apes
Gibbons
Anthropoids
Old World monkeys
Monkeys
New World monkeys
Orangutans
Gorillas
Chimpanzees
Humans
Figure 17.36
The Evolution of Primates
– Primates evolved from insect-eating mammals
during the late Cretaceous period.
– 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
© 2010 Pearson Education, Inc.
– Taxonomists divide the primates into three main
groups:
– The first group of primates includes:
•
•
•
•
Lorises
Pottos
Lemurs
Tarsiers form the second group.
– The third group, anthropoids, includes:
• Monkeys
© 2010 Pearson Education, Inc.
Ring-tailed lemur
Figure 17.37a
Tarsier
Figure 17.37b
Patas monkey (Old World monkey)
Figure 17.37d
Black spider monkey
(New World monkey)
Figure 17.37c
• Hominoids, the ape relatives of humans
© 2010 Pearson Education, Inc.
• And humans
© 2010 Pearson Education, Inc.
Ring-tailed
lemur
Tarsier
Black spider monkey
(New World monkey)
Patas monkey (Old World monkey)
Gorilla (ape)
Orangutan (ape)
Gibbon (ape)
Chimpanzee (ape)
Human
Figure 17.37
The Emergence of Humankind
– Humans and chimpanzees have shared a
common African ancestry for all but the last 5–7
million years.
© 2010 Pearson Education, Inc.
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.
© 2010 Pearson Education, Inc.
– 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.
© 2010 Pearson Education, Inc.
0
?
Homo
Homo
neanderthalensis sapiens
Paranthropus
boisei
0.5
1.0
1.5
Millions of years ago
2.0
2.5
Homo erectus
Paranthropus
robustus
3.0
3.5
Homo
habilis
Australopithecus
africanus
4.0
4.5
5.0
5.5
Australopithecus
afarensis
6.0 Ardipithecus
ramidus
Figure 17.38
– Upright posture and an enlarged brain
appeared at separate times during human
evolution.
– Different human features evolved at different
rates.
– Upright posture was the first human
characteristic to evolve.
© 2010 Pearson Education, Inc.
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.
© 2010 Pearson Education, Inc.
(a) Australopithecus (b) Ancient footprints
afarensis skeleton
(c) Model of an
Australopithecus
afarensis male
Figure 17.39
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
© 2010 Pearson Education, Inc.
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.
© 2010 Pearson Education, Inc.
– Homo erectus:
• Was taller than H. habilis
• Had a larger brain
• Gave rise to Neanderthals
© 2010 Pearson Education, Inc.
Tunicates
Lancelets
Hagfishes
Lampreys
Cartilaginous fishes
Bony fishes
Amphibians
Reptiles
Mammals
Figure 17.UN11
Sponges
Cnidarians
Ancestral
protist
Molluscs
Flatworms
True tissues
Annelids
Roundworms
Arthropods
Bilateral symmetry
Echinoderms
Chordates
Figure 17.UN15
Ancestral
chordate
Chordates
Tunicates
Lancelets
Hagfishes
Vertebrates
Lampreys
Cartilaginous
fishes
Bony fishes
Mammals
Amniotes
Reptiles
Tetrapods
Amphibians
Figure 17.UN16
MOLLUSCS
Gastropods
Bivalves
Cephalopods
Figure 17.UN19
ARTHROPODS
Arachnids
Crustaceans
Millipedes
and Centipedes
Insects
Figure 17.UN20
MAMMALS
Monotremes
Marsupials
Eutherians
Figure 17.UN21