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CLASSIFICATIONInvertebrates
PLANTAE“PROTISTS” ANIMALIAFUNGI
Ap
ico
mp
lexa
ns
Cili
ates
Kin
eto
pla
stid
s
Eu
gle
nid
s
Dip
lom
on
ads
Ph
aeo
ph
yta
(bro
wn
alg
ae)
Oo
myc
ota
(wat
er m
old
s)
Rh
od
op
hyt
a(r
ed a
lgae
)
Ch
loro
ph
yta
(gre
en a
lgae
)
Bry
op
hyt
a(l
iver
wo
rts,
mo
sses
)
Pte
rid
op
hyt
a(f
ern
s)
Zyg
om
yco
ta
Am
oeb
ozo
ans
Asc
om
yco
ta
Bas
idio
myc
ota
Po
rife
ra(s
po
ng
es)
Cn
idar
ia(a
nem
on
es, j
elly
fish
)
Pro
tost
om
es(w
orm
s, a
rth
rop
od
s, m
ollu
sks)
Deu
tero
sto
mes
(sea
urc
hin
s, s
ea s
tars
, ver
teb
rate
s)
Dia
tom
s
Din
ofl
agel
late
s
An
gio
sper
ms
(flo
wer
ing
pla
nts
)
Gym
no
sper
ms
EUKARYOTIC TREE OF LIFE
Fig. 18-7
WHAT ARE THE KEY FEATURES OF ANIMALS?
Animals possess all of the following characteristics Multicellularity Their cells lack a cell wall They obtain energy by consuming other
organisms Most reproduce sexually They are motile at some point in the life cycle They are able to respond rapidly to external
stimuli
AN EVOLUTIONARY TREE OF SOME MAJOR ANIMAL PHYLA
Fig. 23-1
LACK OF TISSUES SEPARATES SPONGES FROM ALL OTHER ANIMALS
Tissues are groups of similar cells that carry out a specific function (e.g., muscle)
Sponges are the only modern-day animals that lack tissues Individual cells in sponges may be specialized, but they act independently and are not organized into true tissues
Sponges and all remaining tissue-containing phyla arose from an ancient common ancestor without tissues
PORIFERA (SPONGES) Sponges have a simple body plan
Sponges belong to the phylum Porifera and are found in most marine and aquatic environments Sponges do not move, but occur in a variety of sizes
and shapes They may reproduce asexually by budding, where the
adult produces miniature versions of itself that drop off and assume an independent existence
They may reproduce sexually through fusion of sperm and eggs
THE DIVERSITY OF SPONGES
Fig. 23-4
CNIDARIANS
Cnidarians are well-armed predators Sea jellies, sea anemones, corals, and
hydrozoans belong to the phylum Cnidaria These animals are mostly marine and are all
carnivorous predators The cells of cnidarians are arranged into distinct
tissues, including a contractile muscle-like tissue and an organized nerve net
CNIDARIAN DIVERSITY
Fig. 23-6
PLATYHELMINTHES (FLATWORMS)
Flatworms may be parasitic or free living Flatworms are bilaterally symmetrical and belong
to the phylum Platyhelminthes Many species are parasites, organisms that live
in or on the body of another organism Non-parasitic, free-living flatworms inhabit
aquatic, marine, and moist terrestrial habitats Flatworms can reproduce both sexually and
asexually; most are hermaphroditic, having both male and female sexual organs
head (attachment site)adult tapeworm
7
5
6
1
2
3
4
8
6 inches
A larvaltapewormis liberated bydigestion and attaches tothe human’sintestine
The tapeworm matures in a humanintestine, producing a series ofreproductive segments; each segmentcontains both male and female sex organs
Eggs are shed fromthe posterior end of theworm and are passedwith human feces
A pig eats foodcontaminated byinfected feces
Larvae hatchin the pig’s intestine
The larvae migrate throughblood vessels to pig muscle
The larvae formcysts in pig muscle
A human eatspoorly cookedpork withlive cysts
THE LIFE CYCLE OF THE HUMAN PORK TAPEWORM
Fig. 23-10
PLATYHELMINTHES (FLATWORMS)
Another group of parasitic flatworms is the flukes
Flukes have complex life cycles that include an intermediate host, such as a snail
Blood flukes cause schistosomiasis, which causes symptoms such as diarrhea, anemia, and possible brain damage
As many as 200 million people worldwide may be infected with flukes
FLATWORM DIVERSITY
Fig. 23-9
ANNELIDA (SEGMENTED WORMS)
Annelids are segmented worms and belong to the phylum Annelida The annelid body is divided into a series of
repeating units (segmentation) The segments contain identical copies of nerves,
excretory structures, and muscles that allows for complex movement
Annelids have a fluid-filled coelom The coelom functions as a hydrostatic skeleton,
where pressurized fluid provides a framework against which muscles can act
DIVERSE ANNELIDS
Fig. 23-12
MOLLUSCA The three classes of mollusks are:
Gastropods Bivalves Cephalopods
MOLLUSCA Gastropods are one-footed crawlers
The snails and slugs are collectively known as gastropods They have a muscular foot for locomotion They may possess a shell, but not all gastropods are
shelled They feed using a radula, a flexible ribbon studded
with spines that scrape algae from rocks or grasp larger plants or prey
Most use their skin and gills for respiration, but terrestrial mollusks have a simple lung
MOLLUSCA Bivalves are filter feeders
Bivalves include scallops, oysters, mussels, and clams They live in fresh water and marine habitats They possess two shells that can be clamped shut by a
strong muscle They are filter feeders and use gills for both feeding
and respiration Most have a muscular foot used for burrowing or for
attaching to rocks
MOLLUSCA Cephalopods are marine predators
Cephalopods have tentacles with chemosensory abilities and suction disks The tentacles are used for locomotion and to capture
prey These animals are able to move rapidly by
forcefully expelling water from the mantle cavity They possess closed circulatory systems
THE DIVERSITY OF CEPHALOPOD MOLLUSKS
Fig. 23-16
ARTHROPODS
Arthropods are the most diverse and abundant animals The phylum Arthropoda includes insects,
arachnids, myriopods, and crustaceans Arthropods have appendages and an
exoskeleton (external skeleton) The exoskeleton is secreted by the epidermis (the
outer layer of skin) It is composed primarily of protein and chitin (a
polysaccharide)
THE EXOSKELETON MUST BE MOLTED
Fig. 23-18
THE DIVERSITY OF ARACHNIDS
Fig. 23-22
THE DIVERSITY OF MYRIAPODS
Fig. 23-23
THE DIVERSITY OF CRUSTACEANS
Fig. 23-24
ECHINODERMS
Echinoderms have a calcium carbonate skeleton
The phylum Echinodermata includes sand dollars, sea urchins, sea stars, sea cucumbers, and sea lilies Echinoderm larvae exhibit bilateral symmetry;
adults show radial symmetry They exhibit deuterostome development They possess an endoskeleton (internal
skeleton) that sends projections through the skin
THE DIVERSITY OF ECHINODERMS
Fig. 23-27
PHYLUM CHORDATA
The phylum Chordata includes two invertebrate groups (the sea squirts and the lancelets) plus the vertebrates