figure 33.0 ochre sea stars, pisaster ochraceus. ancestral protist common ancestor of all animals...
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Figure 33.0 Ochre sea stars, Pisaster ochraceus
ANCESTRALPROTIST
Commonancestor ofall animals
Porifera
Cnidaria
Lophotrochozoa
Ecdysozoa
Deuterostomia
Eum
etazoa Bilateria
Porifera (5,500 species)
A sponge
Cnidaria (10,000 species)
A jelly
Acoela (400 species)
Acoel flatworms (LM)
1.5 mm
Placozoa (1 species)
0.5 mm
A placozoan (LM)
Ctenophora (100 species)
A ctenophore, or comb jelly
Platyhelminthes(20,000 species)
A marine flatworm
Acanthocephala(1,100 species)
Curvedhooks
An acanthocephalan (LM)
Mollusca(93,000 species)
An octopus
A ribbon worm
A cycliophoran(colorized SEM) A marine annelid
100 m
Lophotrochozoa
Nemertea(900 species)
Cycliophora(1 species)
Ectoprocts A rotifer (LM)
A brachiopod0.1
mm
Annelida(16,500 species)
Ectoprocta(4,500 species)
Rotifera(1,800 species)
Brachiopoda(335 species)
Loricifera (10 species)
50 m
Ecdysozoa
A loriciferan (LM)
Priapula (16 species) Onychophora (110 species)
A priapulan
Nematoda(25,000 species)
Tardigrada(800 species)
Arthropoda(1,000,000 species)
An onychophoran
A roundworm(colored SEM)
Tardigrades(colorized SEM)
A scorpion (an arachnid)
100 m
Hemichordata(85 species)
Chordata(52,000 species)
A tunicate
Echinodermata (7,000 species)
An acorn worm
A sea urchinDeuterostomia
Figure 33.UN01
PoriferaCnidaria
LophotrochozoaEcdysozoaDeuterostomia
Figure 33.UN02
Porifera
Cnidaria
Lophotrochozoa
Ecdysozoa
Deuterostomia
Eu
me
tazo
a
(a) These colonial polyps are members of class Hydrozoa.
(b) Many species of jellies (classScyphozoa), including thespecies pictured here, are bioluminescent. The largest scyphozoans have tentaclesmore than 100 m long dangling from a bell-shaped body up to 2 m in diameter.
(c) The sea wasp (Chironex fleckeri) is a member of class Cubozoa. Its poison,which can subdue fish andother large prey, is more potent than cobra venom.
(d) Sea anemones and othermembers of class Anthozoaexist only as polyps.
Anatomy of a planarian
A rotifer
Lophophore
Lophophore
Lophophore
Ectoprocts, such as this sea mat (Membraniporamembranacea), are colonial lophophorates.
In phoronids such as Phoronis hippocrepia, the lophophore and mouth are at one end of an elongated trunk.
Brachiopods have a hinged shell. The two parts of the shell are dorsal and ventral.
(a) (b) (c)
Table 33.3 Major Classes of Phylum Mollusca
A chiton
The results of torsion in a gastropod
A bivalve: Scallop
Anatomy of a clam
Cephalopods: Squid (top left and bottom left), nautilus (top right), octopus (bottom right)
Anatomy of an earthworm
Classes of Phylum Annelida
Parapodia
Free-living nematode
External anatomy of an arthropod
Scorpions have pedipalps that are pincers specialized for defense and the capture of food. The tip of the tail bears a poisonous stinger.
(a) Dust mites are ubiquitous scavengers in human dwellings but are harmless except to those people who are allergic to them (colorized SEM).
(b) Web-building spiders are generally most active during the daytime.
(c)
50 µm
Class Dipolopoda (millipedes)
Anatomy of a grasshopper, an insect
Metamorphosis of a butterfly
Crustaceans: Lobster (top left), banded coral shrimp (bottom left), barnacles (right)
Ancestral colonialchoanoflagellate
Eumetazoa
Bilateria
Deuterostomia
Po
rife
ra
Cn
ida
ria
Oth
er b
ila
teri
an
s (i
ncl
ud
ing
Nem
ato
da
, A
rth
rop
od
a,M
oll
usc
a, a
nd
An
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Ech
ino
de
rmat
a
Ch
ord
ata
Anatomy of a sea star
(a) A sea star (class Asteroidea) (b) A brittle star (class Ophiuroidea)
(c) A sea urchin (class Echinoidea) (d) A feather star (class Crinoidea)
(e) A sea cucumber (class Holothuroidea) (f) A sea daisy (class Concentricycloidea)