The Kingdom ANIMALS

Eukaryotic cells Multicellular Heterotrophic by ingestion

Classification Tools for Animals

1. Body Symmetry 2. Level of Body Organization 3. Body Cavities:Presence of a Coelom 4. Embryological Development: Protostome vs

Deterostome 5. Segmentation / Cephalization 6. Presence of a Notochord 7. Presence of a Vertebral Column

1. Body Symmetry

A. Asymmetry B. Radial Symmetry C. Bilateral Symmetry D. (Pentaradial symmetry – Echninoderms)

Example: Porifera Sea Sponges and Corals

a. Asymmetry –No symmetry at all!

Porifera

Radial Symmetry

Example: Cnidaria

Cnidaria and Radial Symmetry

Cnidaria actually go through a developmental stage of bilateral symmetry before they develop their radial symmetry as an adult.

Sea Anemone

Crown Jellyfish

Soft Coral Polyps

Bilateral Symmetry – Candy striped Annelid

Blue Spotted Sting Ray

Marine Flatworm

African Elephants

2. Levels of Organization

A. Cellular – no true tissues B. Tissues C. Organ

a. Cellular Level of Organization

Porifera are really just an assemblage of different specialized cells. They have no tissues or organs

b. Tissue Level of Organization

Cnidaria have two tissue layers surrounding it’s sac body plan. They do not have any organs or organ systems

c. Organ Level of Organization

Platyhelminthes (flatworms) are the first animals on the phylogenetic tree that have simple organs. They have very primitive “brains” in their “heads”-called cephalization

Platyhelminthes (flatworms)- have simple organs and exhibit simple cephalization

Organ System Level of Organization

As we move up the evolutionary tree, organ systems become increasingly more complicated

Body Cavities

A. Sac body plan B. tube-within-a-tube body plan

- Acoelomates

- Pseudocoelomates

- Coelomates

a. Sac Body Plan – only one opening for food to enter and wastes to exit

Porifera (sponges) Cnidaria (jellyfish) Platyhelminthes

(flatworms)

b. Tube-Within-A-Tube Body Plan

Implies that there is an entrance (mouth) for nutrients and an exit (anus) for wastes

Most primitive animal with this plan:

Nematodes

Acoelomates, Pseudocoelomates, and Coelomates

Acoelomates:Animals without a Coelom

There is no internal body cavity aside from the digestive cavity

Pseudocoelomates: Animals with an internal body cavity that is partially lined with mesoderm

Coelomates: Animals with a true Coelom

A true coelom is an internal body cavity that is completely lined with mesoderm

4. Embryo Development: Protostome vs. Deuterostome

5. Segmentation – Annelids, Arthropods and Chordates

Repetition of body parts along the length of the body

Leads to specialization of parts because various segments can become differentiated for specific purposes

Segmentation

- easily seen in the Arthropods

6. Presence of a Notochord

A notochord is a supporting rod that runs down the dorsal surface, just below the nerve cord. Animals that have a notochord are called chordates.

Vertebrate vs Invertebrate.

External Fertilization

vs Internal Fertilization

a. Invertebrate Chordates: Tunicates

most animals that have notochords also have vertebrate. However, there are 2 groups that do not.

Those animals that do not have vertebrate are called the INVERTEBRATE CHORDATES

a. Invertebrate Chordates: Lancelets

Vertebrates – Chordates with a backbone