26.1 INTRODUCTION TO THE ANIMAL KINGDOM By John Kass and Courtney Pham

What is an Animal?  Animals are multicellular, eukaryotic heterotrophs whose cells lack cell walls  Members of the kingdom Anamalia  95% of animals are Invertebrates (don’t have a Backbone)  5% of animals are vertebrates (have a Backbone)

What Animals do to Survive  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, Respiration, circulation, Excretion, Response, movement, and Reproduction

 Feeding-Most animals eat their food  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-all animals take in O2 and give off CO2  Diffusion across moist surfaces (earthworm) Gills in aquatic animals Lungs in terrestrial animals  Circulation-Very small animals rely on diffusion Larger animals have circulatory system  Open Circulatory System - some vessels, body cavity is "washed" with blood Closed Circulatory System - all blood is enclosed in vessels, capillaries deliver to organs

 Excretion- Primary waste product is ammonia Liquid waste (poisonous substance containing nitrogen)  Diffusion can release wastes in simple aquatic animals  Excretory system in terrestrial animals removes waste without loss of water Response- respond in environment by using nerve cells  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  All phyla in the animal kingdom are related by a common evolutionary heritage  Complex animals tend to have high levels of cell specialization and internal body organization, bilateral body symmetry, a front end or head with sense organs, and a body cavity  Embryos of complex animals develop in layers

 Cell Specialization and Levels of Organization  As animals evolve, their cells become specialized to carry out different functions, such as movement and response  Single-celled organisms move nutrient and waste directly across cell membranes  Ex. Amoeba  Multicellular organism have a structure and chemical composition in each cell that enables it to perform specialized functions  Early Development  Animals that reproduce sexually begin life as a zygote  Zygote- fertilized egg  Zygote undergoes a series of divisions to form a blastula  Blastula- hollow ball of cells  Blastula folds in on itself, forming a single opening called a blastopore  The blastopore leads into a central tube  This tube becomes the digestive tract and forms in one of two ways

Early development continue  Protostome- an animal whose mouth is formed from the blastopore Most invertebrate animals are protostomes  Deuterostome- an animal whose anus is formed from the blastopore  Anus- the opening which wastes leave the digestive tract  Echinoderms and all vertebrates are deuterostomes  The anus is formed before the mouth  Cells differentiate into three layers called germ layers in early development  Endoderm- innermost germ layer, develops into the linings of the digestive tract and much of the respiratory system  Mesoderm- middle layer, gives rise to muscles and much of the circulatory, reproductive, and excretory organ systems  Ectoderm- outermost layer, gives rise to sense organs, nerves, and outer layer of skin

Symmetry -Every animal exhibits some kind of body symmetry except sponges Radial symmetry- like a bicycle wheel, when any number of imaginary planes can be drawn through the center to divide the body in equal halves  Bilateral symmetry- only one single imaginary plane can divide the body into two equal halves  Anterior- the front end of an animal with bilateral symmetry  Posterior- the back end of an animal with bilateral symmetry  Dorsal- the upper side  ventral- the lower side  Bilateral symmetry allows segmentation  Segmentation- when the body is constructed of many repeated and similar parts, or segments  Ex. Worms, insects, vertebrates

 Cephalization  Animals with bilateral symmetry usually have cephalization  Cephalization- concentration of sense organs and nerve cells at the front end of the body  Ex. Dragonfly  Body Cavity Formation  Most animals have a body cavity  Body cavity- fluid filled space that lies between the digestive tract and the body wall  Body cavity provides a space where internal organs can be suspended so they are not pressed by muscles or twisted out of shape by body movement  Body cavities also allow specialized regions to develop  Body cavities provide room for internal organs to grow and expand

Ch Flatworms By Kevin Markose and Cristian Maldonado

Flatworms  Flatworms are soft, flattened worms that have tissues and internal organ systems.  They are the simplest animals to have 3 embryonic germ layers, cephalization, and bilateral symmetry.  Flatworms are known as aceolomates which means “without coelom”  Coelom is a fluid-filled body that is lined with tissue derived from mesoderm.

-Form and Function of Flatworms  Flatworms rely on diffusion for simple functions such as respiration, excretion, and circulation. -Feeding  Flatworms have a digestive cavity with a single opening, or mouth, through which food and waste passes. (eww)  The Pharynx is a muscular tube near the mouth that they use to pump food into the “gut” or digestive cavity.  The food is digested by the gut molecules and then diffusion allows the nutrients to be carried to other body tissues. -Respiration, Circulation, and Excretion  Because they are so flat and thin, most flatworms use diffusion instead of a circulatory system to transport materials.  Flatworms have no respiratory system, no heart, blood vessels, or blood.  In with the good out with the bad.  Some flatworms have specialized cells that remove excess water called “Flame Cells”

-Response  In free-living flatworms, a head encloses several ganglia.  Ganglia are groups of nerve cells that control the nervous system, kind of like the brain but not complex enough.  Two cords run across each side of the body with shorter nerve cords resembling a ladder.  Many free-living flatworms have things that look like eyes near the anterior end of their bodies.  Each eye is actually and eyespot that is a group of cells that can detect changes in the amount of light in an environment.  In addition, most flatworms have specialized cells that detect external stimuli, such as chemicals or the direction in which water is flowing. -Movement- In two ways  Free living flatworms move using Cilia on their epidermal cells, which halp them glide through the water. The second way is using muscle cells controlled by the nervous system allowing them to twist and turn so they can react to environmental stimuli. -Reproduction- Most is hermaphrodites that produce sexually. Hermephrodite is an individual that has both male and female reproductive organs. Also produces asexually by fission which is when an organism splits in two and each half grows new parts to become a complete organism.

Groups of Flatworms  Groups of Flatworms- The main groups of flatworms: Turbellarions, flukes, and tapeworms. Most terbellarians are free-living while most other species are parasites.  Turbellarians= free living flatworm that mostly live in marine or freshwater  Most species are bottom dwellers living in the sand or mud under stones and shells  Vary greatly in color, form and size  Members of the class Turbellaria  picture

Flukes  Members of the class trematoda  parasitic flatworm that mostly infect internal organs of host

Tapeworms  members of the class cestoda  tapeworms= long, flat, parasitic worms that are adapted to life inside the intestines of their host  have no digestive tract  absorb food that has already been digested through their body walls  Scolex= head of an adult tapeworm, also can contain suckers or hooks, used to attach to the intestine wall Proglottids- segments that make up most of the worms body  Testes- produces sperm, or male reproductive organs that can fertilize eggs of other tapeworms or of the same individual  Once eggs are fertilized, proylotids break off and burst to release the zygotes.  -the zygotes are passed out of the host in feces  Cyst- dormant protective stage that the larvae from once they are in intermediate hosts such as cows, fishes, etc  If humans eat raw meat containing cysts the larvae become active and grow into adult worms within the human intestine.