Animal Phylogeny

Parazoa

Phylum Porifera

Cell Grade

Click link to view examples.

Eumetazoa

Phylum Cnidaria

Diploblastic Acoelomates

Class Hydrozoa

Dominant Polyp Stage
Reduced Medusa Stage

Click link to view examples.

Eumetazoa

Phylum Cnidaria

Diploblastic Acoelomates

Class Hydrozoa

Dominant Polyp Stage
Reduced Medusa Stage

Obelia sp.

Gastrozooid and gonozooid polyps.

Eumetazoa

Phylum Cnidaria

Diploblastic Acoelomates

Class Hydrozoa

Dominant Polyp Stage
Reduced Medusa Stage

Obelia sp.

Gastrozooid.

Eumetazoa

Phylum Cnidaria

Diploblastic Acoelomates

Class Hydrozoa

Dominant Polyp Stage
Reduced Medusa Stage

Obelia sp.

Medusae.

Eumetazoa

Phylum Cnidaria

Diploblastic Acoelomates

Class Hydrozoa

Dominant Polyp Stage
Reduced Medusa Stage

Hydra sp.

Solitary polyp.

Eumetazoa

Phylum Cnidaria

Diploblastic Acoelomates

Class Hydrozoa

Dominant Polyp Stage
Reduced Medusa Stage

Hydra sp.

Budding polyp.

Eumetazoa

Phylum Cnidaria

Diploblastic Acoelomates

Class Scyphozoa

Dominant Medusa
Reduced Polyp

Sea Wasp

Carybdea alata

Medusa

Eumetazoa

Phylum Cnidaria

Diploblastic Acoelomates

Class Anthozoa

No Medusa Stage

Subclass Hexacorallia

Dominant Polyp Stage
Stony/Madreporite Corals
and Anemones

Click link to view examples.

Eumetazoa

Phylum Cnidaria

Diploblastic Acoelomates

Class Anthozoa

No Medusa Stage

Subclass Octocorallia

Dominant Polyp Stage
Soft/Gorgonian Corals

Eight Bipinnate Tentacles

Click link to view examples.

Eumetazoa

Bilateria

Protostomia

Lophotrochozoa

Phylum Platyhelminthes

Triploblastic Schizocoelomates

Planaria sp.

Free-living Turbellarian

Eumetazoa

Bilateria

Protostomia

Lophotrochozoa

Phylum Platyhelminthes

Triploblastic Schizocoelomates

Clonorchis sinensis

Chinese liver fluke - parasitic trematode.

Eumetazoa

Bilateria

Protostomia

Lophotrochozoa

Phylum Platyhelminthes

Triploblastic Schizocoelomates

Fasciola hepatica

Sheep liver fluke - parasitic trematode.

Eumetazoa

Bilateria

Protostomia

Lophotrochozoa

Phylum Platyhelminthes

Triploblastic Schizocoelomates

Taenia pisiformis

Scolex.

Parasitic cestode.

Eumetazoa

Bilateria

Protostomia

Lophotrochozoa

Phylum Platyhelminthes

Triploblastic Schizocoelomates

Taenia solium

Mature proglottid.

Parasitic cestode.

Eumetazoa

Bilateria

Protostomia

Lophotrochozoa

Phylum Mollusca

Schizocoelous Protostomes

Class Polyplacophora

Chitons

8 dorsal shell plates.

Eumetazoa

Bilateria

Protostomia

Lophotrochozoa

Phylum Mollusca

Schizocoelous Protostomes

Class Bivalvia

Clams

Laterally compressed.

2-lateral shell valves.

Eumetazoa

Bilateria

Protostomia

Lophotrochozoa

Phylum Mollusca

Schizocoelous Protostomes

Class Gastropoda

Snails, Slugs, and Sea Hares

Torsion.

Click link to view examples.

Eumetazoa

Bilateria

Protostomia

Lophotrochozoa

Phylum Mollusca

Schizocoelous Protostomes

Class Cephalopoda

Octopi and Squid

Click link to view examples.

Eumetazoa

Bilateria

Protostomia

Lophotrochozoa

Phylum Annelida

Schizocoelous, Metameric Protostomes

Class Oligochaeta

Earthworms

Eumetazoa

Bilateria

Protostomia

Lophotrochozoa

Phylum Annelida

Schizocoelous, Metameric Protostomes

Class Polychaeta

Errant and sedentary polychaetes

Click link to view examples.

Eumetazoa

Bilateria

Protostomia

Lophotrochozoa

Phylum Annelida

Schizocoelous, Metameric Protostomes

Class Hirudinoidea

Leeches

Eumetazoa

Bilateria

Protostomia

Ecdysozoa

Phylum Nematoda

Triploblastic Pseudocoelomates

Ascaris sp.

Parasitic nematode.

Cross-section.

Eumetazoa

Bilateria

Protostomia

Ecdysozoa

Phylum Nematoda

Triploblastic Pseudocoelomates

Trichinella spiralis

Parasitic nematode.

Whole mount of juvenile in nurse cell.

Eumetazoa

Bilateria

Protostomia

Ecdysozoa

Phylum Nematoda

Triploblastic Pseudocoelomates

Trichinella spiralis

Parasitic nematode.

Cross-section of juvenile in nurse cell.