Kingdom Animalia
Invertebrates
 All animal
phyla except
Phylum Chordata
(the chordates)
 97% of animals
are invertebrates
Review of animal phylogeny
Parazoa: Phylum Porifera
 No Embryonic Tissues
 Asymmetrical
 Mostly Marine
Sponges are filter feeders
Choanocyte : specialized
feeding cells
Skeletal fibers:
Spicules- calcium carbonate or silica
collagen protein: spongin
Sponges
Group Radiata
•
•
•
•
Radial Symmetry
Diploblastic
Phylum Cnidaria
Phylum Ctenophora
Phylum Cnidaria
• Jellyfish, hydras,
sea anemones,
corals
• Exist as polyp or
medusa body form
• Gastrovascular
cavity with single
opening
Figure 33.4 Polyp and medusa forms of cnidarians
Figure 33.7 The life cycle of the hydrozoan Obelia (Layer 3)
Cnidaria have unique cells called cnidocytes
Some cnidocytes
contain stinging
capsules called
nematocysts
Table 33.1 Classes of Phylum Cnidaria
Classes of Cnidaria
Hydrozoa
Anthozoa
Scyphozoa
Phylum Ctenophora
• Comb jellies
• Only 100 spp.
• Rows of cilia
Group Bilateria
• Bilateral symmetry
• Triploblastic
• Protostomic or
Deuterostomic
Protostomia- Group 1
Lophotrochozoa:
• Based on new molecular
data
• Includes acoelomates,
Phylum Platyheminthes
• Includes
psuedocoelomates, Phyla
Rotifera
• Includes old Lophophorates
Phyla Bryozoa, Phoronida,
Brachiopoda
• Includes old Protostomia,
Phyla Mollusca, Annelida
Phylum Platyhelminthes – flatworms
• Acoelomate
• Free-living and
parasitic species
• Marine and freshwater
• Mesoderm--> organs,
organ systems,
muscle tissue
• Gastrovascular cavity
with one opening
Table 33.2 Classes of Phylum Platyhelminthes
Class Turbellaria: Planarians
Class Trematoda: Flukes
Child with
schistosomiasis
Class Cestoidea: Tapeworms
Tapeworms have no digestive
track, absorbs food from host
Phylum Rotifera
• common, usu. freshwater
microscopic
• smaller than some protists!
• pseudoceol is hydrostatic skeleton
• complete gut
Lophophorate Phlya
• Phyla Bryozoa, Phoronida, Brachiopoda
• True coelomates
• U-shaped gut
• Circular/U-shaped ridge bearing
ciliated tentacles (lophophore)
Phylum Mollusca: snails, clams, squid, octopi
• Unsegmented
bodies
• Body made of foot,
visceral mass, and
mantle
• Feed using radula
(most)
• Shell secreted by
mantle (most)
Basic Body Plan of a Mollusk
Table 33.3 Major Classes of Phylum Mollusca
Class Gastropoda
• Snails, slugs, abalones
• Torsion
• Herbivores or predators
Class Bivalia
• Scallops, clams,
mussels, oysters
• Shell divided into 2
halves
• Filter feeders
Class Cephlapoda
• Squids, octopus,
nautilus
• largest, fastest,
smartest inverts
• Reduced and
internal shell
• advanced nervous
system – learning
Phylum Annelida
• Segmented: series of
repeating segments
– controlled by separate
muscles
– evolutionary important
for movement
• hydrostatic skeleton
• closed circulatory system
• Cerebral ganglia
• excretory organs –
nephridia
Table 33.4 Classes of Phylum Annelida
Annelids
Oligochaeta
Polychaeta
Hirudinea
Protostomia-Group 2
Ecdysozoa
• Animals that molt
• Phyla Nematoda and
Arthropoda
QuickTime™ and a
Photo - JPEG decompressor
are needed to see this picture.
Phylum Nematoda
•
•
•
•
Roundworms
Pseudocoelomate
Thin cuticle
Complete digestive tract
Some Nematodes are parasitic
Trichinella: trichinosis in humans
Heartworms in
a dog
Ascaris in pig guts
Hookworms and
pinworms can
burrow through
the skin
Figure 33.26 External anatomy of an arthropod
Phylum Arthropoda
• Insecta, Arachnida,
Crustacea
• Exoskeleton made of
chitin and protein
• Jointed appendages
• Body segments: head,
thorax, abdomen
Table 33.5 Some Major Arthropod Classes
Trilobites
• Jointed appendages,
very diverse
• Once dominant
• Closest living
relative: horseshoe
crab
Horseshoe crabs: a living
fossil (a chelicerate)
Class Arachnida
• Spiders, scorpions, mites
• 2 body regions
– 2 pairs of appendages
on head (feeding)
– 4 pairs of legs on
cephalothorax
• Many inject digestive
enzymes
• Tracheae or book lungs
• Simple eyes (often
multiple)
Class Diplopoda & Chilopoda
• Millipedes
– 2 pairs of legs/segment
• Centipedes
– 1 pair of legs/segment
– Poison claws for
paralyzing prey
Class Insecta
•At least 1.5 million
species
•3 regions, 1 pair of
antennae on head, 3
pairs of legs on thorax,
usu. 2 (1) pairs of
wings
•Tracheae takes air to
all parts of body
Table 33.6 Some Major orders of Insects (Anoplura-Dermaptera)
Table 33.6 Some Major orders of Insects (Diptera-Hymenoptera)
Table 33.6 Some Major orders of Insects (Isoptera-Odonata)
Table 33.6 Some Major orders of Insects (Orthoptera-Trichoptera)
Insects grow by metamorphosis
Complete metamorphosis
Class Crustacea
• decapods (crabs,
shrimp, crayfish),
isopods, amphipods,
copepods
• most aquatic, marine
• 3 body regions (fused
segments)
• Multiple appendages
• carapace, gills
Crustac
ean
pictures
Phylum Echinodermata
• Deuterostomes
• Sea stars, sea urchins,
brittle stars, sea lilly,
sea cucumbers
• Radial symmetry
QuickTime™ and a
GIF decompressor
are needed to see this picture.
Echinoderms have a water vascular
system including tube feet which function
in movement and feeding
Echinoderms have an endoskeleton
of calcareous plates
Table 33.7 Animal phyla