Animal Kingdom What is an Animal

Animal Kingdom, What is an Animal • Multicellular eukaryotes made up of many specialized cells • Heterotrophic • Adult animals develop from embryos: small masses of unspecialized cells • Simple animals can regenerate or grow back missing parts Symmetry and Strategy • The general structure of an organism is its body plan • Anterior (front end), and posterior (rear) end • The left and right sides of most animals are nearly mirror images. • Their body plan is bilaterally symmetrical. A. This body plan works well for animals, if a body part is damaged, the animal can rely on an identical part on its other side. B. This symmetry provides balance that aids movement. C. Anterior and dorsal defenses such as bones, shells, and horns protect delicate internal organs. Radially Symmetrical • Like a wheel, animals with this spend most of their time floating like a buoy or attached to rocks. • This is a successful feeding adaptation. • Differences between the dorsal and ventral surfaces allow jellyfish to float upright; sea anemones grip rocks with their ventral surfaces and collect food with their specialized dorsal surfaces. Architects and engineers use radially symmetrical designs for structures such as fire hydrants and lighthouses so that the structures will be accessible or visible from any horizontal direction Movement of Animals • Organisms that live rooted to one spot are sessile and those that move around are motile. Even the most sessile animals can move at lease part of their bodies. This movement is dependent on how animals obtain food. • Animals are heterotrophs. Animals that eat plants are herbivores, meat eaters are carnivores, those that kill their own food are predators, and rats and raccoons eat both plants and animals and they are omnivores Organ Systems • Cells form tissues, tissues form organs, and organs form organ systems. This is how an organism develops. • These cells have to differentiate and become specialized in various ways. Animal Systems • • • Skeletal-Support, protection-Bones, shells, cartilage Muscular-Movement-Muscles Digestion-Digestion of food and absorption of nutrients-Mouth, stomach, intestine Circulatory-Distribution of nutrients and oxygen; removal of wastes-Heart, blood vessels, blood Respiratory-Absorption of oxygen; removal of CO2-Lungs, gills Excretory-Removal of wastes-Kidneys Nervous-Perception, control of movement, control and coordination of organ system activities-Brain, spinal cord, nerves Endocrine-Control and coordination of organ system activities-Glands Immune-Defense against disease-causing organisms-Blood cells, glands, skin Reproductive-Production of new organisms-Ovaries, testes • • • • • • • • More than 1 million species of animals exist • There are about 35 phyla in the animal kingdom • Most animal embryos have 3 layers of cells A. The inner layer becomes the lining of the digestive system. B. The outer layer becomes the skin, or other outer covering, and the nervous system. C. The middle layer develops into the organs, such as muscles and blood vessels, that lie between the skin and the digestive system. D. In more complex animals the middle layer splits and forms a fluid-filled cavity. Animal Diversity Sponges and Cnidaria • Very primitive, considered barely animals. • Don’t have true organs or nerve or muscle cells • Sessile animals live attached to rocks. • Get food from water that is pumped through their hollow bodies by cells with flagella Unsegmented Worms • • • • • • • • Roundworms and flatworms are among the simplest bilaterally symmetrical animals Flatworms don’t need respiratory or circulatory systems Thin flat bodies absorb oxygen and release CO2 and wasted directly in the surrounding water. Considered parasitic, they live in the digestive systems of other animals. Nematodes, or roundworms, are less than 1 mm long. There are loads of nematodes in soil and water. Some are decomposers others parasites of animals or plants Pinworms and hookworms in soil burrow into the skin of people who go barefoot outdoors Trichina worms infest people who eat undercooked pork or wild game. • Segmented Worms • Earthworms, leeches, and other segmented worms live in water or damp soil • Leeches were once used to suck out people’s “excess” blood and reduce harmful high blood pressure. • Leeches are uses today to produce anti-bloodclotting medicines, to suck blood from bruises, and to stimulate blood circulation in severed limbs that have been surgically reattached. • Each segment is separated from its neighbors by a membrane and has its own excretory system and branches of the main nerves and blood vessels that run the length of the animal. • Both segmented and unsegmented worms have definite anterior and posterior ends. • Food travels through the digestive system in one direction; from anterior to posterior. • A cluster of nerve cells at the anterior end serves as a simple brain. • Reproduction occurs by splitting or by mutual fertilization. Segmented Worms (cont.) Mollusks • Includes snails, clams, slugs, squid, and their relatives. • Mollusks have soft bodies with 3 parts A. A mass that contains most of the organs B. A muscular “foot” that is used in movement C. A thick flap called a mantle, which covers the body and in most species produces a heavy shell of calcium compounds. Mollusks (cont.) • Mollusks pump water through gills • This is how food is also ingested for clams and oysters. Squid and octopuses use the pump for jet propulsion through the water in search of prey. Arthropods • The largest animal phylum, and have jointed external skeletons. • 1 million species, crabs, shrimp, spiders, scorpions and insects make up this phylum • Arthropods molt, have heads with many sensory organs. • Simple and complex eyes that detect only light intensity and form images • Antennae that smell chemical substances in the environment, arthropods also respond to water vapor, like biting mosquitoes. Arthropods (cont) • They reproduce sexually, where sperm is released inside the female’s body, not in water. • Larvae of many species develop into very different adults, a process called metamorphosis. • Arthropods development of resistance to insecticides demonstrates how quickly they adapt to a changing environment. • Short generations and many offspring increase the chance that random mutations will produce a few resistant individuals Echinoderms • Sea stars and sea urchins. • Reproduce sexually. Sperm and eggs are released in water, where they meet and join. • Movement by seawater into and out of a system of internal tubes. Chordates • Vertebrates-fish, amphibians, reptiles, birds, and mammals. • Four characteristics A. Stiff dorsal rod helps to organize the embryo's development. B. The central nervous system (brain and spinal cord) is tubular C. Their sides have slits just behind the head. These pharyngeal slits (pharynx means “throat”) becomes gill slits of adult fish. In air-breathing chordates, they develop into various organs such as internal parts of the ears D. They have a tail; in humans it’s the tailbone, or coccyx, which curls internally.