26.1 INTRODUCTION TO THE ANIMAL KINGDOM

By John Kass and Courtney Pham

What is an Animal?

Animals are multicellular, eukaryotic heterotrophs whose cells lack cell walls

Members of the kingdom Anamalia 95% of animals are Invertebrates (don’t

have a Backbone) 5% of animals are vertebrates (have a

Backbone)

What Animals do to Survive

Homeostasis is maintained by internal feedback mechanismsFeedback inhibition = the product or results of a process stops or limits the processEx: dog panting releases heat

There are 7 essential functions of animals: Feeding, Respiration, circulation, Excretion, Response, movement, and Reproduction

Feeding-Most animals eat their food Herbivore = eats plants

Carnivore = eats animalsOmnivore = eats plants and animalsDetritivore = feed on decaying organic materialFilter Feeders = aquatic animals that strain food from waterParasite = lives in or on another organism (symbiotic relationship)

Respiration-all animals take in O2 and give off CO2

Diffusion across moist surfaces (earthworm)Gills in aquatic animalsLungs in terrestrial animals

Circulation-Very small animals rely on diffusionLarger animals have circulatory system

Open Circulatory System - some vessels, body cavity is "washed" with bloodClosed Circulatory System - all blood is enclosed in vessels, capillaries deliver to organs

Excretion- Primary waste product is ammoniaLiquid waste (poisonous substance containing nitrogen)

Diffusion can release wastes in simple aquatic animals Excretory system in terrestrial animals removes waste without loss

of water

Response- respond in environment by using nerve cells

Receptor cells = sound, light, external stimuliNerve cells -> nervous system

Movement- Most animals are motile (can move)Muscles usually work with a skeleton

Reproduction:Most reproduce sexually = genetic diversityMany invertebrates can also reproduce asexually = to increase their numbers rapidly

Trends in Animal Evolution All phyla in the animal kingdom are

related by a common evolutionary heritage

Complex animals tend to have high levels of cell specialization and internal body organization, bilateral body symmetry, a front end or head with sense organs, and a body cavity Embryos of complex animals develop in

layers

Cell Specialization and Levels of Organization

As animals evolve, their cells become specialized to carry out different functions, such as movement and response

Single-celled organisms move nutrient and waste directly across cell membranes Ex. Amoeba

Multicellular organism have a structure and chemical composition in each cell that enables it to perform specialized functions

Early Development Animals that reproduce sexually begin life as a zygote

Zygote- fertilized egg Zygote undergoes a series of divisions to form a blastula

Blastula- hollow ball of cells Blastula folds in on itself, forming a single opening called a

blastopore The blastopore leads into a central tube This tube becomes the digestive tract and forms in one of two ways

Early development continue Protostome- an animal whose mouth is formed from the

blastopore Most invertebrate animals are protostomes

Deuterostome- an animal whose anus is formed from the blastopore Anus- the opening which wastes leave the digestive tract Echinoderms and all vertebrates are deuterostomes

The anus is formed before the mouth Cells differentiate into three layers called germ layers in early

development Endoderm- innermost germ layer, develops into the linings of

the digestive tract and much of the respiratory system Mesoderm- middle layer, gives rise to muscles and much of the

circulatory, reproductive, and excretory organ systems Ectoderm- outermost layer, gives rise to sense organs, nerves,

and outer layer of skin

Symmetry -Every animal exhibits some kind of body symmetry except sponges Radial symmetry- like a bicycle wheel, when any number

of imaginary planes can be drawn through the center to divide the body in equal halves

Bilateral symmetry- only one single imaginary plane can divide the body into two equal halves Anterior- the front end of an animal with bilateral

symmetry Posterior- the back end of an animal with bilateral

symmetry Dorsal- the upper side ventral- the lower side

Bilateral symmetry allows segmentation Segmentation- when the body is constructed of many

repeated and similar parts, or segments Ex. Worms, insects, vertebrates

Cephalization Animals with bilateral symmetry usually have

cephalization Cephalization- concentration of sense organs and

nerve cells at the front end of the body Ex. Dragonfly

Body Cavity Formation Most animals have a body cavity

Body cavity- fluid filled space that lies between the digestive tract and the body wall

Body cavity provides a space where internal organs can be suspended so they are not pressed by muscles or twisted out of shape by body movement

Body cavities also allow specialized regions to develop Body cavities provide room for internal organs to grow and

expand

Ch. 27.1 Flatworms By Kevin Markose and Cristian

Maldonado

Flatworms

Flatworms are soft, flattened worms that have tissues and internal organ systems.

They are the simplest animals to have 3 embryonic germ layers, cephalization, and bilateral symmetry.

Flatworms are known as aceolomates which means “without coelom”

Coelom is a fluid-filled body that is lined with tissue derived from mesoderm.

-Form and Function of Flatworms Flatworms rely on diffusion for simple functions such as

respiration, excretion, and circulation.

-Feeding Flatworms have a digestive cavity with a single opening, or

mouth, through which food and waste passes. (eww) The Pharynx is a muscular tube near the mouth that they

use to pump food into the “gut” or digestive cavity. The food is digested by the gut molecules and then

diffusion allows the nutrients to be carried to other body tissues.

-Respiration, Circulation, and Excretion Because they are so flat and thin, most flatworms use diffusion

instead of a circulatory system to transport materials. Flatworms have no respiratory system, no heart, blood vessels, or

blood. In with the good out with the bad. Some flatworms have specialized cells that remove excess water

called “Flame Cells”

-Response In free-living flatworms, a head encloses several ganglia. Ganglia are groups of nerve cells that control the nervous system,

kind of like the brain but not complex enough. Two cords run across each side of the body with shorter nerve cords

resembling a ladder. Many free-living flatworms have things that look like eyes near the

anterior end of their bodies. Each eye is actually and eyespot that is a group of cells that can

detect changes in the amount of light in an environment. In addition, most flatworms have specialized cells that detect

external stimuli, such as chemicals or the direction in which water is flowing.

-Movement- In two ways Free living flatworms move using Cilia on their epidermal cells,

which halp them glide through the water. The second way is using muscle cells controlled by the nervous system allowing them to twist and turn so they can react to environmental stimuli.

-Reproduction- Most is hermaphrodites that produce sexually. Hermephrodite is an individual that has both male and female reproductive organs. Also produces asexually by fission which is when an organism splits in two and each half grows new parts to become a complete organism.

Groups of Flatworms

Groups of Flatworms- The main groups of flatworms: Turbellarions, flukes, and tapeworms. Most terbellarians are free-living while most other species are parasites.

Turbellarians= free living flatworm that mostly live in marine or freshwater

Most species are bottom dwellers living in the sand or mud under stones and shells

Vary greatly in color, form and size Members of the class Turbellaria picture

Flukes

Members of the class trematoda parasitic flatworm that mostly infect internal organs of

host

Tapeworms

members of the class cestoda tapeworms= long, flat, parasitic worms that are adapted to life

inside the intestines of their host have no digestive tract absorb food that has already been digested through their body

walls Scolex= head of an adult tapeworm, also can contain suckers or

hooks, used to attach to the intestine wall

Proglottids- segments that make up most of the worms body Testes- produces sperm, or male reproductive organs that can

fertilize eggs of other tapeworms or of the same individual Once eggs are fertilized, proylotids break off and burst to

release the zygotes. -the zygotes are passed out of the host in feces Cyst- dormant protective stage that the larvae from once they are

in intermediate hosts such as cows, fishes, etc If humans eat raw meat containing cysts the larvae become active

and grow into adult worms within the human intestine.