Section 2 Invertebrates and Vertebrates Chapter 32 Objectives Compare symmetry, segmentation, and body support in invertebrates and vertebrates. Describe the differences in the respiratory and circulatory systems of invertebrates and vertebrates. Compare the digestive, excretory, and nervous systems of invertebrates and vertebrates. Contrast reproduction and development in invertebrates and vertebrates.

Section 2 Invertebrates and Vertebrates Chapter 32 Invertebrate Characteristics Adult invertebrates show large amount of morphological (form or structural) diversity. Invertebrates may be characterized based on their: –Symmetry (radial or bilateral) –Segmentation –Support of the Body –Respiratory and Circulatory Systems –Digestive and Excretory Systems –Nervous System –Reproduction and Development

Segmentation Chapter 32 Segmentation in animals refers to a body composed of a series of repeating similar units. –in its simplest form each unit of the body is similar to the next one –in more complex forms, segments may look different and have different functions

Support of the Body Chapter 32 An animal's skeleton provides a framework that supports the animal's body and is vital to an animal's movement. Many soft-bodied invertebrates, such as jellyfish, have a hydrostatic skeleton, which is a water-filled cavity that is under pressure. (Balloon) An exoskeleton is a rigid external skeleton that encases the body of an animal. –Insects, clams, and crabs have exoskeletons..

Section 2 Invertebrates Chapter 32 Respiratory and Circulatory Systems The respiratory system is responsible for exchanging oxygen and carbon dioxide between the body and the environment. –occurs either directly across the body covering or through internal gills.

Circulatory System In most animals, the circulatory system moves blood or a similar fluid through the body to transport oxygen and nutrients to cells, and carbon dioxide and wastes away from cells. Animals may have one of the following: –no circulatory system –an open circulatory system –a closed circulatory system Chapter 32

Circulatory System In an 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. In a closed circulatory system, the blood is pumped through the body within vessels and is never in direct contact with the body's tissues. Chapter 32

Open and Closed Circulatory System Chapter 32

Section 2 Invertebrates Chapter 32 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.

Digestive System A gastrovascular cavity is a digestive cavity with only one cavity. There are no specialized digestive cells. The hydra has a gastrovascular cavity. Chapter 32

Digestive System 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. Chapter 32

Section 2 Invertebrates Chapter 32 Nervous System The nervous system carries information about the environment through the body and coordinates responses and behaviors. –range from simple, with no neurons, to complex, with a high degree of cephalization and a complex brain. –The phylum Mollusca exhibits the progression of cephalization and the evolution of the brain. The most highly cephalized mollusk is the octopus.

Simple Nervous Systems All animals except sponges have nerve cells, neurons. In the simplest arrangement of nerves, called a nerve net, nerve cells do not coordinate actions efficiently. –Jellyfish and hydras have a nerve net. Chapter 32

Hydra Nerve Net

Many animals have clusters of nerve cells called ganglia that can coordinate responses. Flatworms have large more-complex ganglia, similar to a brain.

Flatworm Nervous System

Complex Nervous Systems More-complex invertebrates have a true brain with sensory structures, such as eyes, associated with it.

Section 2 Invertebrates Chapter 32 Reproduction and Development Invertebrates are capable of sexual reproduction, and many can also reproduce asexually. –Some invertebrates are hermaphrodites. Two patterns of invertebrate development occur : –Indirect development has an intermediate stage called a larva (plural, larvae). –Direct development has no larval stage. Pg. 659

Section 2 Invertebrates and Vertebrates Chapter 32 Vertebrate Characteristics Vertebrates are chordates that have a backbone. –Classes of vertebrates include fishes, amphibians, reptiles, birds, and mammals. Many characteristics of terrestrial vertebrates are adaptations to life on land and fall into two broad categories: –support of the body –conservation of water

Section 2 Vertebrates Chapter 32 Segmentation and Support of the Body Vertebrates segmentation is evident in the ribs and the vertebrae of vertebrates. –As terrestrial vertebrates evolved from aquatic vertebrates –Their limbs and associated muscles evolved to give the animals better support and greater mobility. Vertebrates have an endoskeleton that grows as the animal grows.

Chapter 32 Vertebrate Skeleton Section 2 Invertebrates and Vertebrates

Chapter 32 Body Coverings The outer covering of an animal is called the integument. –Aquatic animals adapted only to moist environments. –Terrestrial vertebrates are adapted to the dry conditions. Integuments serve other purposes such as respiration, protection, or insulation.

Section 2 Vertebrates Chapter 32 Respiratory and Circulatory Systems Gas exchange occurs in the gills of aquatic vertebrates. Lungs evolved in terrestrial vertebrates. Vertebrates have a closed circulatory system with a multichambered heart. In some vertebrates, the multichambered heart has separate chambers and is more efficient.

Chapter 32 Open and Closed Circulatory Systems Section 2 Vertebrates

Chapter 32 Digestive and Excretory Systems Digestion occurs in the gut. In many vertebrates, the gut is very long and folded. Most vertebrates must expel wastes while conserving water. –Most convert ammonia to less toxic substances. In most vertebrates, kidneys filter wastes from the blood while regulating water levels in the body. Digestive and Excretory Systems

Section 2 Vertebrates Chapter 32 Nervous System Vertebrates have highly organized brains, and the control of specific functions occurs in specific centers in the brain. The structure and function of the nervous system vary among vertebrate classes. –Fishes have limited neural circuitry devoted to simple decision making. –Many mammals display complex and flexible behavior.

Section 2 Vertebrates Chapter 32 Reproduction and Development External or internal Most vertebrates undergo direct development.

Chapter 32 Major Vertebrate Organ Systems Section 2 Invertebrates and Vertebrates