Biology: Life on Earth, 5th Edition
Teresa and Gerald Audesirk
Comparison of the Major Animal Phyla
Common Name
Sponges
Hydra, Anemones, Jellyfish
Flatworms
Roundworms
Segmented Worms
Worms
(Phylum)
Body Plan
(Porifera)
(Cnidaria)
(Platyhelminthes)
(Nematoda)
(Annelida)
Level of
organization
Germ layers
Symmetry
Cephalization
Body cavity
Segmentation
Digestive System
Cellular – lack
tissues and organs
Absent
Absent
Absent
Absent
Absent
Intracellular
Tissue – lack organs
Organ system
Organ System
Organ system
Circulatory
System
Respiratory
Respiratory
System
Excretory System
(fluid regulation)
Nervous system
Absent
Two
Radial
Absent
Absent
Absent
Gastrovascular cavity; some
intracellular
Absent
Three
Bilateral
Present
Absent
Absent
Gastrovascular
cavity
Absent
Three
Bilateral
Present
Pseudoceol
Absent
Separate mouth
and anus
Absent
Three
Bilateral
Present
Coelom
Present
Separate mouth
and anus
Closed
Absent
Absent
Absent
Absent
Absent
Absent
Absent
Nerve net
Reproduction
Sexual; asexual
(budding)
Sexual; asexual (budding)
Excretory gland
cells
Head ganglia
with dorsal and
ventral nerve
cords
Sexual (some
hermaphroditic)
Nephridia
Absent
Canals with ciliated
cells
Head ganglia with
longitudinal nerve
cords
Head ganglia with
paired ventral
cords; ganglia in
each segment
Sexual (some
hermaphroditic)
Support
Endoskeleton of
spicules
Hydrostatic skeleton
Hydrostatic
skeleton
Hydrostatic
skeleton
Internal
Systems
Sexual (some
hermaphroditic);
asexual (body splits)
Absent
Biology: Life on Earth, 5th Edition
Teresa and Gerald Audesirk
Comparison of the Major Animal Phyla
Common Name
Snails, Clams, Squid
Insects, Arachnids, Crustaceans
Sea Stars, Sea Urchins
Vertebrates
(Phylum)
Body Plan
(Mollusca)
(Arthropoda)
(Echinodermata)
(Chordata)
Level of
organization
Germ layers
Symmetry
Organ system
Organ system
Organ system
Organ system
Three
Bilateral
Three
Bilateral
Three
Bilateral
Cephalization
Cephalization
Body cavity
Segmentation
Digestive System
Present
Coelom
Absent
Separate mouth and anus
Present
Coelom
Present
Separate mouth and anus
Circulatory
System
Respiratory
System
Excretory System
(fluid regulation)
Nervous system
Open
Open
Three
Bilateral larvae, radial
adults
Absent
Coelom
Absent
Separate mouth and
anus (normally)
Absent
Gills, lungs
Tracheae, gills, or book lungs
Nephridia
Excretory glands resembling
nephridia
Head ganglia with paired ventral
nerve cords; ganglia in some
segments, some fused
Internal
Systems
Reproduction
Well-developed brain in
some cephalopods;
several paired ganglia,
most in the head; nerve
network in body wall
Sexual (some
hermaphroditic)
Normally sexual
Present
Coelom
Present (but reduced)
Separate mouth and
anus
Closed
Tube feet, skin gills,
respiratory tree
Absent
Gills, lungs
Head ganglia absent;
nerve ring and radial
nerves; nerve network in
skin
Well-developed brain;
dorsal nerve cord
Sexual (some
hermaphroditic); asexual
by regeneration (rare)
Sexual
Kidneys