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 E. Bodies contain tissues F. Contain epithelial tissue that covers the body G. Muscle tissue H. Connective tissue I. Nervous tissue

Invertebrate Invertebrates – animals that do not have a back bone or vertebral column. They range in size from microscopic to a giant squid size of 20 meters in length. Groups – Porifera, Cnidarians, sea stars, worms, jelly fish, and arthropods. Make up 95% of all animals on Earth.

Vertebrates Animals that all have a back bone and a vertebral column Makes up about 5% of all animals that include: Fishes, amphibians, reptiles, birds and mammals.

Survival techniques Feeding – depending on what the animals eats, where it lives, its physical characteristics and surroundings will determine it’s feeding habits. Animals must ingest to receive energy necessary for sustain life. Respiration – All animals, whether they live above or under water must take in Oxygen and give off Carbon Dioxide. Most of these animals contain complex tissues to perform this survival technique. Circulation – a system of vessels that transport blood carrying oxygen and food to tissues and organs. It also removes waste and cleans the blood as it transport through the body. Excretion – Animals that take in must release waste out of their bodies on a regular basis. Waste is toxic and must be removed or it will damage tissues.

Movement – some have a sessile existence but most are motile and can move about. Responding to the environment quickly is a life surviving technique. Reproduction – Either through asexual or sexual, animals reproduce offspring in a variety of ways to instill the survival of their species. Response- Animals use their nerves in order to respond to environment for survival.

Cell specialization and levels of organization Early development stages: Zygote Blastula – hollow ball of cells that eventually become an elongated structure with a tail. This leads into a central tube that becomes the digestive tract formed one of 2 ways. Protostome – animals whose mouth is formed from the blastopore, mostly invertebrates. Deuterostome – animals whose anus is formed from the blastopore. 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 excretory system. Ectoderm – outer most layer that gives rise to the sense organs, nerves and the outer skin.

Body Symmetry Radial symmetry – 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 2 equal halves. They have a left and a right side, usually a front and a back, upper and lower end. 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.