The document discusses key characteristics of animals in the kingdom Animalia. It notes that animals are multicellular, mitochondrial heterotrophs that ingest and digest food internally. There are estimated to be around 9-10 million animal species on Earth across 36 phyla. Most animals exhibit bilateral symmetry and sexual reproduction, and range widely in size and habitat. Advanced animal body plans evolved from simpler multicellular to bilaterally symmetrical to coelomate forms with specialized tissues and organs.

1. KINGDOM ANIMALIA Characteristics of Animals January 16 th , 2007

2. Characteristics of Life 1. Living things are organized. 2. Living things are made up of cells. 3. Living things metabolize. 4. Living things maintain an internal environment. 5. Living things grow. 6. Living things respond. 7. Living things reproduce. 8. Living things evolve.

3. Seven Levels of Taxonomic Classification Kingdom Phylum Class Order Family Genus Species

4. Kingdom Animalia All animals are multicellular, mitochondrial heterotrophs—they have multiple cells with mitochondria and they rely on other organisms for their nourishment. Most animals ingest their food and then digest it in some kind of internal cavity.

5. Animal Species Somewhere around 9 or 10 million species of animals inhabit the earth. About 800,000 species have been identified.

6. Animal Phyla Biologists recognize about 36 separate phyla within the Kingdom Animalia. Animal Phyla Web Page

7. Major Animal Phyla

8. Animal Movement Most animals are capable of complex and relatively rapid movement compared to plants and other organisms.

9. Animal Reproduction Most animals reproduce sexually, by means of differentiated haploid cells (eggs and sperm). Most animals are diploid, meaning that the cells of adults contain two copies of the genetic material.

10. Animal Sizes Animals range in size from no more than a few cells (like the mesozoans) to organisms weighing many tons (like the blue whale). a mesozoan blue whale

11. Animal Habitats Most animals inhabit the seas, with fewer in fresh water and even fewer on land.

12. Animal Cells Animal cells, like all eukaryotic cells, have internal structures called organelles that serve specific functions for the cell. Animal cells lack the rigid cell walls that characterize plant cells.

13. Animal Cell Diagram

14. Animal Bodies The bodies of most animals (all except sponges) are made up of cells organized into tissues. Each tissue is specialized to perform specific functions. In most animals, tissues are organized into even more specialized organs .

15. Animal Symmetry The most primitive animals are asymmetrical. Cnidarians and echinoderms are radially symmetrical. Most animals are bilaterally symmetrical.

16. Radial Symmetry …applies to forms that can be divided into similar halves by more than two planes passing through it. Animals with radial symmetry are usually sessile, free-floating, or weakly swimming.

17. Bilateral Symmetry Animals with bilateral symmetery are most well-suited for directional movement.

18. Radial vs. Bilateral Symmetry

19. Cephalization Bilateral Symmetry usually has led to cephalization—the process by which sensory organs and appendages became localized in the head end of animals.

20. Evolutionary Trends If we analyze the basic body plans of animals, we find that they illustrate evolutionary trends. Four major “advances” (in order): Multicellular body plan Bilaterally symmetrical body plan “ Tube-within-a-tube” body plan Coelomate body plan

21. 3 Major Bilateral Body Plans Acoelomates Pseudocoelomates Coelomates Each plan consists of 3 cell layers: endoderm, mesoderm, ectoderm

23. Acoelomates These animals have no other cavity than the gut. They are often called the “solid worms.”

24. Pseudocoelomates These animals have a body cavity (the pseudocoelom) which is not completely lined with mesoderm. The “tube within a tube” body plan. This category is also composed of mostly worms.

25. Coelomates These animals have a “true coelom” lined with mesodermal peritoneum. Most animals are coelomate.