Transcript Chapter 1
Chapter 1 Section 1- What is an Animal Structure of Animals • Cell – Basic unit of structure and function in living things • Group of cells – tissue – organ • Groups of structures that perform the broadest functions of an animal are systems. Functions of Animals • The major functions of animals are to obtain food and oxygen, keep internal conditions stable, move, and reproduce. Obtaining Food and Oxygen • Obtains food by eating other organisms • Food provides animals with raw materials for growth • To release energy from food, the body’s cells need oxygen. Keeping Conditions Stable • Animals must maintain a stable environment within their bodies. • If the balance is lost, the animal cannot survive for long. • Cells that get too hot start to die = dogs panting Movement • Swimming, walking, hopping • Movement is related to meeting the basic needs of survival and reproduction. Reproduction • Sexual reproduction – develops from the joining of 2 sex cells (fertilization) • Asexual reproduction – process by which a single organism produces a new organism identical to itself. Section 3 Sponges and Cnidarians Sponges • Live mostly in oceans, but in some rivers and lakes • Water currents carry food and oxygen to them and take away their waste products. Body Structure • Invertebrates that have no body symmetry and never have tissues or organs • Belongs to phylum Porifera, which means “having pores” • Has spikes for support and for defense Obtaining Food and Oxygen • Eats tiny single celled organisms • The collar cells that line the central cavity trap tiny organisms • Jelly-like cells inside the sponge then digest the food • Gets oxygen from the water Reproduction • Can reproduce either sexually or asexually • Asexually – budding – new sponges grow from the sides of an adult sponge • Sexually – sponges produce both sperm cells and egg cells Cnidarians • Examples: jellyfishes, corals, sea anemones • Invertebrates that have stinging cells and take food into a central body cavity. • They use stinging cells to capture food and defend themselves. Body Structure • Has 2 different body plans: one looks like a vase and the other looks like an upsidedown bowl. • Vase shaped is called a polyp • A polyp’s mouth opens at the top and its tentacles spread out from around the mouth. • Adapted for life attached to a surface Body Structure • Bowl-shaped is called a medusa • Is adapted for swimming • Have mouths that open downward and tentacles that trail down • Some cnidarians go through both stages during their lives. Obtaining Food • Both types obtain food in the same way • Use stinging cells to catch the animals they eat. • Stinging cell contains a threadlike structure which has many sharp spines. • When this stinging cell touches its prey, this threadlike structure explodes Movement • Can move to escape danger and to obtain food • Some have muscle-like tissues that aid in movement • Jellyfishes swim through the water, and hydras turn slow somersaults • Movement is directed by nerve cells Reproduction • Reproduce both asexually and sexually • Polyps: asexual (budding is most common) • Sexual: some produce both male and female sex cells; some are specifically male or female Life in a Colony • Some cnidarians live in a colony – group of many individual animals. • Examples: Stony corals, Portuguese man-of-war Stony Corals • A coral reef is built by cnidarians • A coral polyp attaches to a solid surface, it produces a hard, stony skeleton around its soft body. • Coral polyp reproduces asexually – when they die, their skeletons remain behind. Portuguese man-of-war • It contains as many as 1,000 individuals that function together as one unit • Top has a gas filled chamber that allows it to float on the top of the ocean • Various polyps drift below Learning Log •What are two examples of asexual reproduction seen in polyps? Answer •Budding •Pulling apart Section 4 Worms