1. Intro to Animal Diversity
Chapter 32

2. What Is An Animal?

3. What Is An Animal?

4. What Is An Animal? Multicellular Heterotrophic Eukaryotic
No cell walls – held together with structural proteins, mainly collagen

5. Body Plans
Animal phyla are categorized based on features that are either present or absent.
Features often included:
Symmetry
Tissue layers
Body cavities
Protostomes vs. deuterostomes

6. Body Symmetry Asymmetrical Radial Bilateral Dorsal & ventral
Anterior & posterior

7. Body Tissues

8. Body Tissues No true tissues (no gastrulation) Diploblastic
Ectoderm & endoderm
Triploblastic
Also has mesoderm

9. Body Cavities
Acoelomate
Pseudocoelomate
Coelomate

10. Protostomes vs. Deuterostomes

11. Protostomes vs. Deuterostomes

13. Animal phylogenetic tree
Zoologists currently recognize about 35 animal phyla
The current debate in animal systematics
Has led to the development of two phylogenetic hypotheses, but others exist as well

14. Animal phylogenetic tree
One hypothesis of animal phylogeny based mainly on morphological and developmental comparisons
Porifera
Cnidaria
Ctenophora
Phoronida
Ectoprocta
Brachiopoda
Echinodermata
Chordata
Platyhelminthes
Mollusca
Annelida
Arthropoda
Rotifera
Nemertea
Nematoda
“Radiata”
Deuterostomia
Protostomia
Bilateria
Eumetazoa
Metazoa
Ancestral colonial
flagellate

15. Animal phylogenetic tree
One hypothesis of animal phylogeny based mainly on molecular data
Calcarea
Silicarea
Ctenophora
Cnidaria
Echinodermata
Chordata
Brachiopoda
Phoronida
Ectoprocta
Platyhelminthes
Nemertea
Mollusca
Annelida
Rotifera
Nematoda
Arthropoda
“Radiata”
“Porifera”
Deuterostomia
Lophotrochozoa
Ecdysozoa
Bilateria
Eumetazoa
Metazoa
Ancestral colonial
flagellate

16. Points of Agreement All animals share a common ancestor
Sponges are basal animals
Eumetazoa is a clade of animals with true tissues
Most animal phyla belong to the clade Bilateria
Vertebrates and some other phyla belong to the clade Deuterostomia

17. Disagreement over the Bilaterians
The morphology-based tree
Divides the bilaterians into two clades: deuterostomes and protostomes
In contrast, several recent molecular studies
Generally assign two sister taxa to the protostomes rather than one: the ecdysozoans and the lophotrochozoans