Chapter 26 Introduction to the Animal Kingdom

What is an animal?  A. All heterotrophs  B. Multicellular  C. Eukaryotic cells  D. Do not have a cell wall on their cells  E. Bodies contain tissues  F. Contain epithelial tissue that covers body surfaces.  G. Muscle tissues  H. Connective tissue  I. Nervous tissue

Invertebrates A. Invertebrates – animals that do not have a back bone or vertebral column.  They range in size from microscopic to a giant squid, 20 meters in length.  Groups – sea stars, worms, jelly fish and insects.  Makes up 95% of all animals on earth

Vertebrates  A. Animals that contain a backbone  This makes up the other 5% of all animals and they include  Fishes, amphibians, reptiles, birds and mammals

Survival techniques in the animal kingdom  Feeding – Depending on what the animal eats, where it lives, it physical characteristics and surroundings will determine it’s feeding habits. Animals must ingest to receive energy necessary for sustaining life.  Respiration – All animals, whether they live under or above water must take in oxygen and give off carbon dioxide. Most of these animals contain complex tissues to perform this survival technique.  Circulation – A systems of vessels that transports blood that carries food and oxygen and rids the body of waste.  Excretion – Animals that take in must release waste of out their bodies. Waste is toxic and it must be removed within a certain amount of time.

 Response – Specialized cells allow animals to respond to their environment for survival.  Movement – Some have a sessile existence and most are motile and can move about. Muscles and attachment to the skeletal system enable most animals to move.  Reproduction – Either through asexual or sexual animals produce offspring in a variety of ways to instill the survival of their species.

Cell Specialization and levels of Organization  Early development stages:  Zygote  Blastula –Hollow ball of cells that eventually becomes an elongated structure with a tube. This leads into a central tube that becomes the digestive tract, formed one of two ways…  Protostome – animals whose mouth is formed from the blastopore, mostly invertebrates.  Deuterostome – animal whose anus is formed from the blastopore. The anus is formed first and the mouth is formed second.  During early development the cells differentiate into 3 layers, Endoderm, inner most germ layer that gives rise to the digestive tract and respiratory system. Mesoderm, middle layer that gives rise to the muscles and much of the circulatory, reproductive and excretory systems. Last the ectoderm, or outer most layer that give rise to the sense organs, nerves and the outer skin layer.

Body Symmetry  Radial symmetry – have body parts that repeat around the center of the body. Examples: sea star and sea anemone.  Bilateral symmetry – a single imaginary plane can divide the body into two equal halves. They have a left and right side, usually a front and a back, and upper and lower ends.  Anterior – front end  Posterior – back end  Dorsal – upper side  Ventral – lower side  Cephalization – a concentration of sense organs and nerve cells at the front end of the body. Animals with this tend to respond more quickly and in more complex ways.