Intro to Invertebrates Chapter 25

Sections 1 & 2

O Invertebrates (inverts) include all animals that lack a backbone, or vertebral column.O This includes 33 Phyla

Phylum PoriferaO The term Porifera means “pore-

bearers” in Latin.O This phylum includes Sponges.O Most ancient member of the

Kingdom Animalia.O One of the most simple organisms

Phylum CnidariaO Organisms include jellyfish,

anemones, hydra, and coral.O These organisms are always aquatic.O Can live in giant colonies such as the

Great Barrier Reef

http://www.youtube.com/watch?v=by1S-kZ4gN4

Phylum NematodaO Range in size from microscopic to 1

meterO Can live on land and in water.O Some are parasiticO Closely related to the phylum

Arthropoda

O http://www.youtube.com/watch?v=SpgjnXEFadg

Phylum Platyhelminthes

O Commonly known as flatworms.O They are the most simple animals to

have 3 germ layers. O Most are only 3mm thick.

O http://www.youtube.com/watch?v=mh2dTIRReXU

Phylum AnnelidaO Includes organisms such as

earthworms and leechesO The word Annelida means little ring

in Latin

Phylum MolluscaO Includes both marine and terrestrial

organismsO Ex. Snails, clams, squid, and octopiO Have a larval stage in developmentO Typically have an internal or external

shell

O http://www.youtube.com/watch?v=WqMNjUp6UeA

EchinodermataO Echino- means spiny in Greek and

Detmis- means skin (spiny skin)O Includes sea urchins, sand dollars,

and Sea StarsO Only live in the seaO Have a structure called “tube feet”

Body Plans of InvertsO Body Symmetry

O Radial Symmetry- a number of imaginary planes drawn through the center of the body will divide the organism in equal halves.O Ex: Sea Stars, Sea Anemone, and Jelly

Fish

O Bilateral symmetry- a single imaginary plane divides the body into left and right sides that are mirror images of each other.O Lobster, earthworms, snails

O Germ Layers-during embryonic development the cells of most animals differentiate into 3 layers, called germ layersO Endoderm- is the inner most layer

and develops the lining of the digestive tract and much of the respiratory system.

O Mesoderm- middle layer that gives rise to muscles and much of the circulatory, reproductive, and excretory systems.

O Ectoderm- outermost layer that produces sense organs, nerves, and the outer layer of the skin

O Body Cavities- a fluid-filled space between the digestive tract and the body wallO The most complex organisms have a

true coelom, which is a body cavity that develops within the mesoderm and is completely lined.

O Pseudocoelom is a partially lined body cavity

O Acoelom there is no body cavity present.

O Segmentation- repeated parts on an animal. Most have repeated body parts on the inside also.

O Cephalization- The concentration of sense organs and nerve cells at the organisms anterior end. (to have a head)O The most successful animal groups

exhibit cephalization.

Review Game

What type of symmetry?

What type of symmetry?

What type of symmetry?