The Animal Kingdom


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)

Physiology = Study of the functions of organs |  Anatomy = the structure of the organism/organs

There are 7 essential functions of animals:

1.  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)

2.  Respiration:
Take in O2 and give off CO2
Lungs, gills, through skin, simple diffusion

3.  Circulation:
Very small animals rely on diffusion
Larger animals have circulatory system which include vessels

4.  Excretion:
Primary waste product is ammonia, liquid waste filtered by the kidneys

5.  Response:
Receptor cells = sound, light, external stimuli

6.  Movement:
Most animals are motile (can move)
Muscles usually work with a skeleton

7.  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 – 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)