Chapter 26: Sponges, Cnidarians, and Unsegmented Worms

Section 1: Introduction to the Animal Kingdom

Introduction to the Animal Kingdom

•The ______is the most diverse in form

•Each animal performs the essential functions of life in its own special way

•Two divisions that we will use to separate the animal kingdom are vertebrates and invertebrates

–______have a backbone

–______have no backbone

What Is an Animal?

•All animals share certain basic characteristics

•Animals are ______(they do NOT make their own food)

•Instead, they obtain the nutrients and energy they need by feeding on organic compounds that have been made by other organisms

•Animals are ______, which means that their bodies are composed of more than one cell

•Animal cells are also ______– they contain a nucleus and membrane-enclosed organelles

•An animal is a multicellular eukaryotic heterotroph whose cells lack cell walls

Cell Specialization and Division of Labor

•The bodies of animals contain many types of specialized cells

•Each specialized cell has a ______, ______

______, and ______

______that make it uniquely suited to perform a particular function within a multicellular organism

•For this reason, groups of specialized cells carry out different tasks for the organism – ______

What Animals Must Do to Survive

•In order to survive, animals must be able to perform a number of essential functions

•For each animal group we study in the next several chapters, we will examine these functions and describe the cells, tissues, organs, and organ systems that perform them

Feeding

•Animals have evolved a variety of ways to feed

•______eat plants

•______eat animals

•______live and feed either inside or attached to outer surfaces of other organisms, causing harm to the host

•______strain tiny floating plants and animals from the water around them

•______feed on tiny bits of decaying plants and animals

Respiration

•Living cells consume ______and give off ______in the process of cellular respiration

•Entire animals must respire, or breathe, in order to take in and give off these gases

•Small animals that live in water or in moist soil may respire through their ______

•For large active animals, however, respiration through the skin is not efficient

•The ______these animals have evolved take many different forms in adaptations suited to different habitats

Internal Transport

•Some aquatic animals can function without an internal transport system

•But once an animal reaches a certain size, it must somehow carry ______, ______, and ______to and from cells deep within its body

•Many multicellular animals have evolved a ______

______in which a pumping organ called a ______forces a fluid called ______through a series of ______

Excretion

•Cellular metabolism produces chemical wastes such as ______that are harmful and must be eliminated

•Small aquatic animals depend on ______to carry wastes from their tissues into the surrounding water

•But larger animals, both in water and on land, must work to remove poisonous metabolic wastes

Response

•Animals must keep watch on their surroundings to find food, spot predators, and identify others of their own kind

•To do this, animals use specialized cells called ______, which hook up together to form a ______

•______, such as eyes and ears, gather information from the environment by responding to light, sound, temperature, and other stimuli

•The ______, which is the nervous system’s control center, processes the information and regulates how the animal responds

•The complexity of the nervous system varies greatly in animals

Movement

•Some animals are ______, which means that they live their entire adult lives attached to one spot

•But many animals are ______, which means that they move around

•To move, most animals use tissues called muscles that generate force by contracting

•In the most successful groups of animals, muscles work together with a skeleton, or the system of solid support in the body

•Insects and their relatives wear their skeletons on the outside of their bodies

–______

•Reptiles, birds, and mammals have their skeletons inside their bodies

–______

•We call the combination of an animal’s muscles and skeleton its musculo – skeletal system

Reproduction

•Animals must reproduce or their species will not survive

•Some animals switch back and forth between asexual and sexual reproduction

•Many animals that reproduce sexually bear their young ______

•Others ______

•The eggs of some species hatch into baby animals that look just like miniature adults

•These baby animals increase in size but do not change their overall form

–______

•In other species, eggs hatch into ______, which are immature stages that look and act nothing like the adults

•As larvae grow, they undergo a process called ______in which they change shape dramatically

–______

Trends in Animal Evolution

•The levels of organization become higher as animals become more complex in form

•The essential functions of less complex animals are carried out on the cell or tissue level of organization

•As you move on to more complex animals, you will observe a steady increase in the number of ______

•You will also see those tissues joining together to form more and more specialized organs and organ systems

•Some of the simplest animals have radial symmetry; most complex animals have bilateral symmetry

•Some of the simplest animals have body parts that repeat around an imaginary line drawn through the center of their body

–______

•Animals with radial symmetry never have any kind of real “head”

•Many of them are sessile, although some drift or move in a random pattern

•Most complex invertebrates and all vertebrates have body parts that repeat on either side of an imaginary line drawn down the middle of their body

•One side of the body is a ______of the other

•These animals are said to have ______

–Animals with bilateral symmetry have specialized front and back ends as well as upper and lower sides

•______= front end

•______= back end

•______= upper side

•______= lower side

•More complex animals tend to have a concentration of sense organs and nerve cells in their anterior (head) end

•This gathering of sense organs and nerve cells into the head region is called ______

•Nerve cells in the head gather into clusters that process the information gathered by the nervous system and control responses to stimuli

•Small clusters of nerve cells are called______