1. Chapter 26 - 1 Introduction to the Animal Kingdom
Most diverse kingdom in appearance
Each phylum has its own typical body plan (arrangement)
What is an Animal?
Animals are heterotrophic, eukaryotic, and multicellular and
lack cell walls.
95% = invertebrates (do not have backbone)
5% = vertebrates (have a backbone)
What Animals do to Survive
Physiology = Study of the functions of organs
Anatomy = the structure of the organism/organs
Homeostasis is maintained by internal feedback mechanisms
Feedback inhibition = the product or results of a process stops or limits the process
Ex: dog panting releases heat
There are 7 essential functions of animals:
Feeding:
Herbivore = eats plants
Carnivore = eats animals
Omnivore = eats plants and animals
Detritivore = feed on decaying organic material
Filter Feeders = aquatic animals that strain food from water
Parasite = lives in or on another organism (symbiotic relationship)
Respiration:
Take in O2 and give off CO2
Lungs, gills, through skin, simple diffusion
Circulation:
Very small animals rely on diffusion
Larger animals have circulatory system
Excretion:
Primary waste product is ammonia
Liquid waste

2. Response:
Receptor cells = sound, light, external stimuli
Nerve cells => nervous system
Movement:
Most animals are motile (can move)
Muscles usually work with a skeleton
Reproduction:
Most reproduce sexually = genetic diversity
Many invertebrates can also reproduce asexually = to increase their numbers rapidly
Trends in Animal Evolution
Cell Specialization and Levels of Organization:
Cells -->tissues -->organs -> organ systems
Early Development:
Zygote = fertilized egg
Blastula = a hollow ball of cells
Blastopore = the blastula folds in creating this opening
Protostome = mouth is formed from blastopore
Deuterosome = anus if formed from blastopore
Anus = opening for solid waste removal from digestive tract
The cells of most animal embryos differentiate into three layers called germ layers
Endoderm = (innermost) develops into the lining of the digestive tract and respiratory tract
Mesoderm = (middle) muscle, circulatory, reproductive, and excretory systems
Ectoderm = (outermost) sense organs, nerves, outer layer of skin
Body Symmetry:

3. Body Symmetry - the body plan of an animal, how its
parts are arranged
Asymmetry - no pattern (corals, sponges)
Radial Symmetry - shaped like a wheel (starfish,
hydra, jellyfish)
Bilateral Symmetry - has a right and left side
(humans, insects, cats, etc)
Cephalization - an anterior concentration of sense
organs (to have a head)
*The more complex the animals becomes the more
pronounced their cephalization
anterior - toward the head
posterior - toward the tail
dorsal - back side
ventral - belly side
Segmentation - "advanced"
animals have body segments,
and specialization of tissue
(even humans are segmented,
look at the ribs and spine)
Body Cavity Formation: A fluid-filled space where internal organs can be suspended
Types of Animals
Phylum Examples Evolutionary Milestone
Porifera sponges multicellularity
Cnidaria jellyfish, hydra, coral tissues
Platyhelminthes flatworms bilateral symmetry
Nematoda roundworms pseudocoelom
Mollusca clams, squids, snails coelom
Annalida earthworms, leeches segmentation
Arthropoda insects, spiders, crustaceans jointed appendages

4. Echinodermata starfish deuterostomes
Chordata vertebrates notochord