Kingdom Animalia
Invertebrate Phyla
Defining Traits
Phylum Porifera
“pore bearing”
-collar cells (choanocytes)
Phylum Cnidaria
Phylum Platyhelminthes
“stinging cells”
“flat worm”
-stinging tentacles
-flattened bodies
-cnidocytes w/ nematocysts -cephalization
Phylum Nematoda
“thread worm”
-roundworms
-cephalization
Symmetry
Germ Layers
Developmental Mode
Coelom
Level of Organization
Segmentation
Cephalization
Nervous
asymmetrical
diploblastic
NONE
NONE
cellular level
absent
absent
NONE
radial or biradial
diploblastic
NONE
NONE
tissue level
absent
absent
-nerve net
bilateral
triploblastic
protostome
pseudocoelomate
organ-system level
absent
present
-ganglia
-multiple nerve cords
-sense organs
Support
INTERNAL
spongin – collagen protein
spicules – crystalline spikes
NONE
EXTERNAL (corals) or NONE
bilateral
triploblastic
protostome
acoelomate
organ-system level
absent
present
-ganglia
-double nerve cord (nerve
ladder)
-sense organs
NONE
-contracting cells in
epidermis
-well-developed contracting -longitudinal layer of
cells in mesoderm
muscles
Digestive
-no digestive cavity
-collar cells (phagocytosis)
-incomplete
-gastrovascular cavity
-incomplete
-gastrovascular cavity
-muscular pharynx
-complete:
mouthintestineanus
Respiratory
-diffusion through
choanocytes
-diffusion
-diffusion
-diffusion
Circulatory
NONE
NONE
NONE
-distribution through body
fluid
Excretory
NONE (diffusion)
NONE (diffusion)
-flame cells filter body
fluids
-excretory tubules and pores -nephridia or simple kidneys -nephridia
-asexual budding
-asexual regeneration
-sexual reproduction
-mostly hermaphrodites
-release egg/sperm in water
Classes
Hexactinellida:
SiO2 skeletons
(Subphyla for Arthropoda) Calcarea:
CaCO3 skeletons
Demospongiae:
collagen skeletons
Sclerospongiae:
SiO2 & CaCO3 skeletons
-asexual budding
-sexual reproduction
-mostly distinct sexes
-release egg/sperm in water
-planula larva
Hydrozoa:
hydras, man o’war, some
corals
Scyphozoa:
jellies, sea nettles
Anthozoa:
anemones, most corals, sea
fans
Cubozoa:
box jellies, sea wasps
-asexual fission
-asexual regeneration
-sexual reproduction
-mostly hermaphrodites
-sexual reproduction
-mostly distinct sexes
-external or internal
fertilization
-sexual reproduction
-mostly distinct sexes
-external fertilization
Turbellaria:
free-living worms
Trematoda:
parasitic flukes
Cestoda:
tapeworms
Monogenea:
fish parasites
Secernentea:
mostly parasitic worms
Chromadorea:
mostly marine worms
Enoplea:
mostly free-living worms
Gastropoda:
snails, slugs, nudibranchs
Bivalvia:
clams, mussels, oysters,
scallops
Cephalopoda:
octopuses, squids,
nautiluses, cuttlefish
Polyplacophora:
chitons
Miscellaneous
-life cycles can include both
asexual polyp and sexual
medusa stages
-epidermis (outside)
-gastrodermis (inside)
-mesoglea (jelly in between)
-planula-type of larva
-larva of Tremotoda,
Cestoda, and Monogenea
resemble the planula larva
of Cnidarians
-some have complex
parasitic life cycles involving
multiple hosts
-some flatworms undergo
parthenogenesis
-non-living cuticle for outer
covering
-important decomposers and
predators of microbes
-siphons: incurrent and
excurrent
-cephalopods are most
intelligent invertebrates
-some snails undergo
parthenogenesis
Muscular
Reproduction
-sessile as adults
-ciliated larvae attach to
bottom of ocean/lake then
grow into adult
-three body plans:
(simplecomplex) asconoid,
syconoid, leuconoid
hydrostatic skeleton
Phylum Mollusca
“soft bodies”
-soft bodies (mantle)
-3 parts: head, foot, visceral
mass
-radula-rasping tongue
bilateral
triploblastic
protostome
coelomate
organ-system level
absent
present
-ganglia
-nerve cord
-sense organs
Phylum Annelida
“little rings”
-metamerism (segmented)
-setae (bristles)
-circular and longitudinal
muscles
bilateral
triploblastic
protostome
coelomate
organ-system level
present
present
-ventral nerve cord with
segmental ganglia
-sense organs
Phylum Arthropoda
“jointed foot”
-exoskeleton (molting)
-head, thorax, abdomen
(sometimes fused)
-metamorphosis
bilateral
triploblastic
protostome
coelomate
organ-system level
present
present
-brain
-ventral nerve cord
-statocyst (balance organ)
-sensory hairs
exoskeleton
Phylum Echinodermata
“spiny skin”
-water vascular system
-no brain, heart, or
respiratory structures
hydrostatic skeleton
(most have a shell)
hydrostatic skeleton
-mantle
-circular and longitudinal
-muscle contractions in foot layers of muscle
-paired muscles with
tendons
-complete:
-complete:
mouthesophagus
mouthpharynx
stomachintestinesanus
esophaguscrop
gizzardintestineanus
-gills or lungs
-diffusion through cuticle
-some have gills
-complete:
mouthpartspharynx
esophagusstomach
intestinesanus
-gills in aquatic species
-book lungs or trachea &
spiracles in land species
-dorsal heart
-open circulatory system
-muscles in tube feet
-muscles between bony
plates
-complete:
mouthesophagus
stomachanus
-open system with heart,
blood vessels, and sinuses
-closed system with 5 pairs
of aortic arches
-sexual reproduction
-distinct sexes or
hermaphrodites
-external fertilization
-green glands
-simple kidneys
-Malpighian tubules
-sexual reproduction
-mostly distinct sexes
-external or internal
fertilization
pentaradial (bilateral larva)
triploblastic
deuterostome
coelomate
organ-system level
absent
absent
-no brain
-nerve ring and nerve cords
-sense organs
endoskeleton
(ossicles – bony plates)
-no system
-diffusion through tube feet
and skin gills
NONE
-diffusion through tube feet
and skin gills
-sexual reproduction
-distinct sexes or
hermaphrodites
-external fertilization
-regeneration
Oligochaeta:
Trilobita:
Asteroidea:
earthworms
trilobites (extinct)
sea stars
Polychaeta:
Chelicerata:
Ophiuroidea:
marine worms
spiders, scorpions, ticks,
brittle stars
Hirudinea:
mites, horseshoe crabs
Echinoidea:
Leeches
Myriapoda:
sea urchins, sand dollars
centipedes, millipedes
Holothuroidea:
Hexapoda:
sea cucumbers
insects, springtails
Crinoidea:
Crustacea:
sea lilies, feather stars
crabs, lobsters, crayfish,
Concentricycloidea:
shrimp, barnacles
sea daisies
-important soil decomposers -greatest number of species -most closely related to
-burrowing action aerates
-exoskeleton prevents drying chordates, similar
sediments and releases
out for terrestrial species
embryonic development
trapped nutrients
-specialized sensory and
-bilateral larva undergo
respiratory structures
metamorphosis to become
-some insects and
radial adults
crustaceans undergo
-marine only (no terrestrial
parthenogenesis
or freshwater species)