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Introduction to Animals CH 26: Introduction to Animals Sec 1 and Sec 2 Section 2 Introduction to Animals Section 2 General Features of Animals • Animals are multicellular, heterotrophic organisms with cells that lack cell walls. • Humans depend on other animals for food, companionship, and to pollinate crops. • Most animals move to get food. But filter eaters, such as sponges and corals, catch particles of food that drift by in the water. Introduction to Animals Section 2 Kinds of Animals • Animals are often grouped as invertebrates or vertebrates. • Vertebrates make up only a subgroup of one phylum— Chordata. • Most animals are invertebrates. Introduction to Animals Section 2 Kinds of Animals, continued Vertebrates • Vertebrates have a cranium and an internal skeleton composed of bone or cartilage. • Vertebrates are chordates that have a backbone. • The backbone supports and protects a dorsal nerve cord and provides a site for muscle attachment. • Pg 625 Introduction to Animals Section 2 CH26 Sec 2: Animal Body Systems Introduction to Animals Section 2 Key Ideas • Why is an animal's skeleton important? • What are the functions of the digestive and excretory systems? • What is the function of the nervous system? • Why are the respiratory and circulatory systems important? • What are two reproductive strategies of animals? Introduction to Animals Section 2 Support • An animal's skeleton provides support for the animal's body and location for muscle attachment. • Many soft-bodied invertebrates, such as jellyfish, have a hydrostatic skeleton – which is a water-filled cavity that is under pressure. • An exoskeleton is a rigid external skeleton that encases the body of an animal. • An endoskeleton is an internal skeleton made of bone and cartilage. Introduction to Animals Section 2 Digestive and Excretory Systems • The digestive system is responsible for extracting energy and nutrients from an animal's food. • The excretory system removes waste products from the animal's body. Introduction to Animals Digestive System • A gastrovascular cavity is a digestive cavity with only one cavity. • The hydra has a gastrovascular cavity. Section 2 Introduction to Animals Section 2 Digestive System, continued • In a digestive tract, food moves from one opening, the mouth, to a second, the anus. • Digestive tracts allow for specialization and more efficient digestion. Introduction to Animals Section 2 Digestive and Excretory Systems, continued Excretory System • The removal of wastes produced by cellular metabolism. • Simple aquatic invertebrates and some fishes excrete ammonia through their skin or gills. • Terrestrial animals need to minimize water loss. Introduction to Animals Section 2 Nervous System • Carries information about the environment through the body and coordinates responses and behaviors. – Nerve net – Ganglia – Brain Introduction to Animals Hydra Nervous System Section 2 Introduction to Animals Flatworm Nervous System Section 2 Introduction to Animals Grasshopper Nervous System Section 2 Introduction to Animals Section 2 Respiratory and Circulatory Systems • The respiratory system is responsible for exchanging oxygen and carbon dioxide between the body and the environment. – Gills – Lungs • The circulatory system transports gases, nutrients, and other substances within the body. Introduction to Animals Section 2 Circulatory System • Open circulatory system – a heart pumps fluid containing oxygen and nutrients through vessels into the body cavity. – The fluid provides oxygen and nutrients as it washes across the tissues. • Closed circulatory system – the blood is pumped through the body within vessels – is never in direct contact with the body's tissues. Introduction to Animals Section 2 Open and Closed Circulatory Systems Introduction to Animals Section 2 Reproduction • Asexual reproduction occurs when an individual produces exact copies of itself and gametes are not exchanged. – Budding – Parthenogenesis – Fragmentation • Sexual reproduction, a new individual is formed by the union of a male and female gametes. • Some species can reproduce either asexually or sexually.
