1. Major Animal Phyla
Porifera, Cnidaria, Platyhelminthes, Annelida, Mollusca, Arthropoda, Echinodermata, and Chordata

2. Overview: Check This Out First

3. Phylum Porifera: Sponges
Have no definite shape – asymmetrical
No tissues or organs
Colony of specialized cells
Immobile
Good powers of regeneration
Skeleton of spongin and spicules

4. CLASSES OF SPONGES Class Calcarea – has calcium carbonate spicules
Class Hexactinellida – glass sponges with spicules of silica
Class Demospongiae – no spicules, only spongin

5. Phylum Cnidaria stinging-celled animals
Jellyfishes, corals, anemones
Radial symmetry
Two tissue layers with inner mesoglea
Primitive nerve net but no brain
2-way digestive tract
Stinging cells for capturing food.

6. CLASSES OF CNIDARIANS
Class Hydrozoa – Hydra, Portuguese-Man-of-War, Obelia; mostly polyp or hydroid stage
Class Scyphozoa – true jellyfishes; mostly medusa stage
Class Anthozoa – corals, anemones
Class Cubozoa – box jellies

7. Phylum Platyhelminthes flatworms
First animals to exhibit bilateral symmetry
Have primitive brain
3 tissue layers
Includes free-living flatworms and parasitic flatworms (tapeworms, flukes)

8. CLASSES OF FLATWORMS Class Turbellaria – free-living flatworms
Class Cestoda – tapeworms
Class Trematoda - flukes

9. Phylum Annelida segmented worms
Earthworms, sandworms, leeches
One-way digestive system
Have well-developed digestive and circulatory systems

10. CLASSES OF ANNELIDS
Class Oligochaeta – earthworms, bloodworms; oligo- means “few” and chaeta means a “bristle” or stout hair
Class Polychaeta – many bristles and parapodia (fleshly lobes to “walk” with
Class Hirudinea – leeches (most are NOT bloodsuckers)

11. Phylum Mollusca- soft bodied animals
includes snails, slugs, nudibranchs, chitons, limpets, clams, oysters, squid, octopus, nautilus, etc.
Either have no shell, one shell, or two shells
Many have hard mouth parts (radula in gastropods, beak in cephalopods).

12. CLASSES OF MOLLUSCS
Class Gastropoda – snails, slugs, conchs, nudibranchs; have either no shell or one shell; name means “stomach foot”
Class Bivalvia – clams, oysters, mussels; have two shells that hinge together
Class Polyplacophora – chitons; snail-like with 8 embedded plates on its back
Class Cephalopoda – squid, octopus, nautilus, cuttlefish; name means “head foot”; well-developed nervous system

13. Phylum Arthropoda – joint-legged animals
includes insects, crustaceans, centipedes, millipedes, and arachnids
exoskeleton made of chitin
must shed shell to grow

14. CLASSES OF ARTHROPODS
Class Crustacea – shrimps, lobsters, crabs, crawfishes
Class Amphipoda – small; called scuds
Class Isopoda – sea lice; some are parasitic
Class Stomatopoda – mantis shrimps
Class Pycnogonida – sea spiders
Class Merostomata – horseshoe crabs
Class Cirripedia - barnacles

15. Phylum Echinodermata – spiney-skinned animals
includes sea stars, brittle stars, sea urchins, sand dollars, sea cucumbers, and crinoids
reverted back to radial symmetry (radial in adults / bilateral in larvae)
tube feet and water vascular system
Most exhibit pentamerism

16. WHY ARE ECHINODERMS RANKED SO HIGH?
Clues from embryology – study of the early development of animals
Protostome – blastopore forms the mouth in all animals except echinoderms and chordates
Deuterostomes – blastopore forms the anus in echinoderms and chordates

17. CLASSES OF ECHINODERMS
Class Asteroidea – sea stars
Class Ophiuroidea – brittle stars, serpent stars
Class Echinoidea – sea urchins, sand dollars
Class Holothuroidea – sea cucumbers
Class Crinoidea – sea lilies, feather stars

18. Phylum Chordata
Includes fish, amphibians, reptiles, birds, and mammals
Dorsal hollow nerve tube
Notochord
Pharyngeal gill slits
Post anal tail