The
Animal
Kingdom
True Body Cavity
a
body cavity is any
fluid filled space in a
multicellular organism.
 However, the term
usually refers to the
space, located
between an animal’s
outer covering
(epidermis) and the
outer lining of the gut
cavity, where internal
organs develop.
Cell Layers
Cells on the outside of the embryo
(ectoderm) will become skin and nerve
cells.
While inner groups of cells (endoderm)
will give rise to the gut.
And the cells in between (mesoderm) will
produce bone and muscle tissues, and
the circulatory, excretory and reproductive
systems.
Phylum Porifera
Sponges
Definitions 1.1
 Endoderm
└ The inner germ layer that develops
into the lining of the digestive and
respiratory
systems.
 Mesoderm
└ The middle germ layer that
develops into muscle and bone and
cartilage and blood
and
connective tissue.
Sub Groups - Classes
Class Calcarea
Class Demospongiae
Class Hexactinellida
No
openings to the digestive
system – cells lining pores simply
extract food from water
passing through pores.
Two cell layers – outer
ectoderm and inner endoderm
(no mesoderm)
No true body cavity
Distinguishing Characteristics
All
marine
Have pores through which food
is filtered
Phylum Cnidaria
 One
opening to the digestive system
for obtaining food and releasing
waste -Internal sack for digestion
called the gastrovascular cavity
3
cell layers-outer layer=epidermis,
middle =mesoglea, inner layer
=gastrodermis
 No
true body cavity
Subgroups
 Anthozoa=true
corals. Anemones and sea
pens
 Cubozoa= box jellies with complex eyes
and potent toxins
 Hydrozoa=most diverse group with
siphonophores, hydroids, fire corals, and
many medusae
 Scyphozoa=true jelly fish
Distinguishing Characteristics
 Aquatic
or marine organisms
 Have tentacles which are armed with
stinging cells named nematocysts
 Nematocysts eject barbed threads tipped
with poison
 Radial symmetry
Examples in Queensland
 Box
jelly fish - Cubozoa
 Bulb-tentacle Anemone – Anthozoa
 Blue bottles -Hydrozoa
Phylum
Platyhelminthes
From the Greek platy for flat
and helminthes for worms,
Hence Flat Worms
 Have
three cell layers (endo, meso and
ectoderm)
 Have only one opening to the digestive tract.
 No true body cavity
Distinguishing Characteristics
 Bilaterally
symmetrical
 Flattened worm-shape body
 Many are hermaphrodites (both
male and female sexual organs)
 Have a simple nervous system
 Live in aquatic environments or
within another organism
(endoparasites)
5 classes
 Turbellaria
 Trematoda
 Aspidogastrea
 Monogenea
 Cestoda
Examples
 Planaria

Dugesia tigrina
 Liver



(Turbellaria)
Flukes (Trematodes)
Opisthrochis sinensis (human liver fluke)
Fasciola hepatica (sheep liver fluke)
Schistosoma mansonii (blood fluke)
 Tapeworms


(Cestoda)
Taenia pisiformes (dog tapeworm)
Taenia
Taenia soleum (pig tapeworm)
soleum
South-East Queensland
 Lives
a long distance from the sea water
 Found under rocks and rotting logs
around mangroves
 relatively thick, fleshy and oval body, and
is well camouflaged against the mud by
its brown body and dark spots
Leopard Flatworm
Myoramyxa
pardalota
Blue-lined flatworms
Pseudoceros sp.
Prostheceraeus, a flatworm of the class
Turbellaria
Nematodes
Round Worms
Melisa Chang and Angelique Burden
Three
cell layers
Two digestive openings – mouth
and anus
No true body cavity
Subgroups
 Dipogasteria
 Rhabditia
 Spiruia
 Tylenchia
Distinguishing Characteristics
 Live
in soil or are parasites including humans.
 Unsegmented worms with long cylindrical
rounded body, pointed at both ends (round
worms)
 have reproductive, nervous and excretory
systems,.
 Bodies are bilaterally symmetrical
 Most are microscopic but can grow to 8 metres
in length
Examples of Roundworms
 Pin
worms
Annelids
 Three
cell layers
 Two openings to the digestive system –
mouth and anus
 True body cavity
Distinguishing Characteristics
 Segmented
bodies
 Long cylindrical shaped bodies
 Some have small bristles along length of
body (not true appendages)
 Live in moist environments
Examples
 Earth
worms
 Polychaetes
bristle worm
– pink
 Polychaete
worm
 Leeches
Arthropods
© Lauren and India
Three
cell layers
True Body Cavity Arthropods have
body cavities; their main internal
cavity is a hemocoel, which
accommodates their internal
organs and through which their
blood circulates - they have open
circulatory systems
Two openings to the digestive
cavity
Distinguishing
Characteristics
 Segmented
body
Body made up of more than one
part. Spiders have two segments
and insects have three
segments.
 Many
jointed legs or limbs
 Exoskeleton
- external skeleton.
Examples (Classes)
 Crustacea
 Arachnida
 Insecta
 Chilopoda
(millipedes)
 Diplopoda (centipedes)
Molluscs
 The
Mollusca have three cell layers
 The body cavity in molluscs is a true body
cavity
 Two openings to the digestive tract
Distinguishing Characteristics
 unsegmented
soft body
 most have internal or
external shell
 have a mantle - a fold in
the body wall that
secretes the hard
protective shell
 muscular foot and/or
tentacles
 have a radula - a
toothed structure used
to grate food
Examples of the Phylum
 Snails
 Slugs
 Octopi
 Limpets
 Nautiluses
 Cuttlefish
 Clam
Molluscs in South East QLD
 Mud
Whelks
Molluscs in South East QLD
 Trochus
.
Shells
Phylum
Echinodermata
 Three
cell layers
 Two openings to the
digestive system
 True body cavity
Characteristics
 Exclusively
marine (only found in ocean)
 Endoskeleton – spiny
 Radial Symmetry -Five or more arms
Echinoderms exhibit a wide range
of colours.
Sea Cucumber
Zebracrab
Urchin clingfish
Feather star
Sea Urchin
Many snake stars
Examples
Sea urchin
Egyptian Sea Star
Spiny Cushion Starfish
Coleman shrimp
Toxic sea urchin
Shrimpfish
Chordata
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Includes vertebrates, urochordata and
cephalochordata
But not all chordata are vertebrates
Distinguishing features






Chordates is defined by having at some stage in
their lives all of the following:
A notochord - a fairly stiff rod of cartilage that
extends along the inside of the body. In fish and
other vertebrates this develops into the spinal
cord,
A dorsal nerve cord
A pharyngeal slits - the part of the throat
immediately behind the mouth.
A muscular tail - extends backwards behind the
anus. (missing in primates)
They all have true body cavity, 3 cell layers and
two openings to the digestive system
Urochordata – sea squirts
Cephalochordata - lancelets
 Small,
"vaguely fish-shaped" animals that
lack brains
 Usually found buried in sand in shallow parts
of temperate or tropical seas
Vertebrates – animals with
backbone
 Includes:
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Mammals
Birds
Amphibians
Reptiles
fishes