Classifying AnimalsThe Invertebrates

Objectives:1.Describe the characteristics used to classify animals into different groups2.Discuss the characteristics of animals in different phyla3.Explain how each successful phyla have become more complex and able to occupy more diverse habitats

Thinker…

• Why is it thought that prokaryotic cells are more primitive than eukaryotic cells?

What Kingdom do I belong to?

• I am Prokaryotic.• I can live almost

anywhere.• I reproduce asexually.• I usually have a cell

wall.• I am heterotrophic

(eat food) or autotrophic (make my own food.)

Eubacteria

Plantae

• I am multicellular• I have a cell wall• I make my own food

(autotroph)

Protista

• I might be prokaryotic or eukaryotic

• I live in moist habitats • I can make my own

food but some of my friends have to consume their food

• I can be plant-like or animal-like

• I can make you sick

Fungi

• I am a heterotroph• I am sometimes

confused with a plant• I am usually

multicellular• I reproduce using

spores

Archaebacteria

• I am prokaryotic• I live in harsh

conditions (salt lakes, hot springs and animal guts)

• I am a heterotroph• I do have a cell wall,

but it is different from my cousins the Eubacteria

Animalia

• I am multicellular• I usually reproduce

sexually• My cells don’t have

walls• I can fly, swim, walk

or run

Classifying animals•There are six commonly recognized Kingdoms

– Eubacteria, Archaebacteria, Protista, Fungi, Plantae and Animalia

The animal kingdom can be split, further, into two main groups:

• animals with backbones (vertebrates)• animals without backbones (invertebrates).

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Phylum

• There are more than 30 phyla in the animal kingdom.

• All but one of these phyla are invertebrates

• We belong to the one phyla that has vertebrates (Phylum Chordata)

Characteristics of all Animals• Heterotrophic (ingest and digest food)

• Multicellular and some have specialized tissues and organs

• Cells lack cell walls.

Most reproduce sexually and produce an embryo.

Classification…Organisms are classified based on several criteria…1.Level of body organisation2.Number of body layers3.Symmetry4.Body cavities5.Movement6.Reproduction7.Digestion

1. Level of body organisation

• Are the cells organised into tissues or not?

• Are the tissues organised into organs or not?

• Are organs organised into organ systems?

2. Number of body layers• Two layers: Endo and Ectoderm

• Three layers: Endo, Ecto and Mesoderm

Mesoderm gives rise to tissues and structures including bone, cartilage and muscle

3. Symmetry

• Asymmetry: Irregular shape

• Radial:

• Bilateral: Each half is

a mirror image of the

other.

4. Body cavities• Coelom: Fluid filled

space inside the body (a body cavity)

• Acoelomate: No coelom

• Pseudocoelomate: Partially formed (not complete)

• Coelomate: True body cavity completely lined with mesoderm

5. Movement

• Sessile: Not able to move around– May have been able to at one point in

development

• Motile: Able to move

6. Reproduction

• Asexual: Offspring from single parent

• Sexual: Offspring from two parents

7. Digestion

• Sac-like: Mouth used for both intake of nutrients and exit of wastes

• Tube-like: Separate openings for food intake and waste exit (Mouth and anus)

The Invertebrates…

• Can you think of what organisms might be included in the invertebrate group???

• Of the approximately 30 phylum of invertebrates there are 6 you should know…

The Simplest AnimalsPhylum Porifera (Sponges):

Once thought to be plants

Cells are not arranged into specialized tissues or organs.

No nervous system or brain

No muscle tissue – No movement

Rely on water flow for

nutrients which are

absorbed through pores

in their outer wallshttp://www.ucmp.berkeley.edu/porifera/porifera.html

Invertebrates(5 other phyla)

molluscsarthropods

Annelida (segmented worms

echinodermscnidarians

jellyfish

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Your Task

• Groups of 4 or 5

• Become experts, in your expert groups, on your chosen phyla of invertebrates.

• Be prepared to teach others in your home group all about your phyla.

Plenary1. What distinguishes invertebrates from other

organisms?

2. What are the different characteristics used to classify invertebrates?

3. What are the six phyla of invertebrates?

4. Tell me three things you learned in this lesson.

5. Tell me two things you already knew before this lesson?

6. What is one thing you would like to know more about? How can you find out?

Invertebrates Continued…

Today you will teach the members of your home group all about your

phyla of invertebrates

Your task…

• Get together with your expert group to review your phyla. (5 min)

• Get back into your home groups and teach about your phyla (35 min). Make sure you can answer questions about your phyla.

• As a group, answer the questions on your handout. Discuss your answers and come to a consensus about the answers

Phylum Cnidaria• Exhibits radial symmetry.• Cells organized into tissues.• E.g., hydrozoans, jellyfish, sea

anemones, sea fans and corals.

Phylum CnidariaTwo Main Cell Layers

1. • Covers outer body surfaces.• Some have muscle fibers or nerve nets which allows it to

react to environmental stimuli.

2. • Covers inner body surfaces.

** Mesoglea:• A jelly-like layer between ectoderm and gastroderm.

Ectoderm

Endoderm

Phylum Cnidaria

• All cnidarians have stinging structures within their tentacles.• Toxic substances paralyze prey.

• Mouth/anus leads to gastrovascular cavity.• Where digestion, circulation and gas

exchange occur.

Phylum Cnidaria

• Lifecycle alternates between asexual sessile polyps and sexual free-swimming medusas.

Phylum Cnidaria

Portuguese Man-of-War

• Tentacles may be up to 55 m in length.

Annelida and Mollusca

Body Plan• Exhibits bilateral symmetry.

• Each half is a mirror image of the other.• Dorsal: • Ventral: FRONT

BACK

Body Plan• Cephalization (Position of nervous

structures).• Sense organs and nerve cells concentrate at

anterior end.• Bilaterally symmetrical animals move through

environment with anterior end forward.

• Coelom (fluid-filled body

cavity).

EctodermMesodermCoelom

Endoderm

Phylum Annelida“Segmented Worms”

• Live in marine, freshwater and terrestrial environments.

• Segmented bodies and a coelom.

• Segmentation allows for larger growth and enhanced locomotion.

•

•

Phylum Mollusca

“Animals with a Shell”

• Includes snails, slugs, clams, squids and octopuses.

• Moist, muscular body without a skeleton.

All Mollusks

• Have a…– Complete digestive tract– Body cavity (coelom)– Bilateral symmetry for at least part

of their lives

• They have primitive brains and can sense their environment using sense organs located on top of their head.

Phylum MolluscaBody Plan

1. • Locomotion and feeding.

2. • Tissue that covers gills and secretes

shell.

3. • Internal Organs.

Muscular Foot

Mantle

Visceral mass

Phylum Mollusca

Class Bivalva

• Includes clams, oysters, scallops, mussels and other shellfish.

• Flexible hinge connects two shells.

• Have no head

• They don’t move much

• Filter feed

Phylum Mollusca

Class Gastropoda

• Includes snails and slugs.

• Use foot for locomotion.

• Respiration through gills and moist skin.

•

          

                    

          

                    

                              

Name means “stomach footed”

Phylum Mollusca

Class Cephalopoda• Includes squids, octopuses and

nautilus.• Shell reduced to an internal rod.

– Improves movement.• Cephalopoda means ‘head

footed’• Most complex mollusks• Arms with suckers• Sexual reproduction

Phylum Echinodermata

“Radially Symmetrical Marine Animals”• Includes sea stars, sea urchins, sand dollars

and sea cucumbers.• Larvae:• Adults:

• Have an endoskeleton (internal skeleton) with spiny projections.

• Water vascular system:

Bilateral Symmetry

Radial Symmetry (5 similar body segments = pentamerous)

Phylum Echinodermata

Phylum Arthropoda

“Animals with an Exoskeleton”

• 1, 170, 000 species (mostly insects).

• Segmented bodies, exoskeleton (external skeleton), jointed legs and blood cavity.

• Exoskeleton composed of chitin:• • •

Non-Living Material

Jointed AppendagesOutside skeleton protects muscles, organs and blood vessels.

Joint-Legged Animals

Phylum Arthropoda

• As arthropods grow, they molt or shed exoskeleton and grow a new one.

• • Gills evolved in aquatic arthropods.• Tracheae developed in terrestrial arthropods.

• • Open circulatory system.• Blood cavity directly bathes internal organs.

Respiration

Circulation

• Nervous System: Simple to complex

• Digestive System made of three parts:– Foregut – mouth to esophagus– Midgut - stomach– Hindgut – intestine to anus

• Reproduction:Sexual

Phylum Arthropoda

Class Arachnida

• Includes scorpions, spiders, mites and ticks.

• Cephalothorax: head fuses to thorax.

• 4 pairs of legs

Phylum ArthropodaClass Crustacea• Includes shrimp, lobsters, crayfish and

crabs.• Three body segments:

• Head, Thorax and Abdomen

• Paired appendages attach to each segment.• Two pair of antennae• Three pair of feeding appendages

• Respiration: Gills

Phylum Arthropoda

Class Insecta• 1.5 million species.• Three body segments:

• Head, Thorax and Abdomen

• Antennae on head sense environment.• Three pairs of walking legs on thorax.• May be one or two pairs of wings• Respiration:

• Air sacs and trachea that extend from external openings to tissues.

Phylum Arthropoda

• Flying Insects: Two pairs of stiff wings attached to thorax.

• Flies: One pair of wings.

• Beetles: Front wings form hardened wing covers.

Phylum Arthropoda

Plenary…

• Discuss answers to questions as a class.

Home Work…• For each phylum we have learnt about,

describe how their structure is adapted to their habitat (Hint: pg 416, 427, 441)

• What main characteristics are used to classify animals into different phyla?

• Turn to pg 441. Do the classifying Invertebrates activity.

• Turn to pg 445. Do question 25

H/W Finish answering questions on handout

Worm-like AnimalsPhylum Platyhelminthes, Phylum Nematoda, Phylum

Nematoda and Phylum Annelida

Body Plan• Exhibits bilateral symmetry.

• Each half is a mirror image of the other.• Dorsal: • Ventral:

Body Plan

• Cephalization.• Sense organs and nerve cells concentrate at

anterior end.• Bilaterally symmetrical animals move through

environment with anterior end forward.

• Coelom (fluid-filled body cavity).

Phylum Platyhelminthes“The Flatworms”

• No coelom due to flattened body.

• Branched gastrovascular cavity increases surface area for digestion.

• Many are marine parasites.

Phylum PlatyhelminthesClass Turbellaria• Predators of scavengers• Marine and freshwater species.

Class Trematoda• Parasitic flatworms (blood flukes).• Sucker attaches fluke to host.• Can cause serious disease in humans

Phylum PlatyhelminthesClass Cestoda

• Tapeworms (eat the food in our digestive tract)

• Flat body composed of many sections.

• Suckers and hooks attach tapeworm to intestines.

Phylum Nematoda“The Roundworms”

• Have a complete digestive tract

• Scavengers in soil and found at bottoms of lakes and ponds.

• Some are parasites

• Trichinosis

• 10,000 species identified.

• Microscopic to 1 m in length.

Phylum Annelida“Segmented Worms”

• Live in marine, freshwater and terrestrial environments.

• Segmented bodies and a coelom.• Segmentation allows for larger growth and

enhanced locomotion.• More advanced brain• More advanced digestive

system

Sources

• http://www.underwater.com.au/image.php/id/5254/• http://www.stanford.edu/class/humbio103/

ParaSites2006/Taenia_saginata/Introduction.html• http://www.mbari.org/benthic/other.html• http://www.solaster-mb.org/mb/platyhelminthes.htm• http://www.scienceclarified.com/Oi-Ph/Parasites.html• http://www.seaslugforum.net/showall.cfm?base=flatworm• http://www.onset.unsw.edu.au/issue7/Tapeworm.bmp• http://www.cbu.edu/~seisen/PlatyhelminthesReview.htm• http://www.levitated.net/notes/ECC/• http://www.bu.edu/lernet/GK12/eric/index.html

Joint-Legged Animals

Phylum Arthropoda“Animals with an Exoskeleton”

• 1, 170, 000 species (mostly insects).

• Segmented bodies, exoskeleton (external skeleton), jointed legs and blood cavity.

• Exoskeleton composed of chitin:• Non living• Thick and heavy or thin and light• Provides protection

Phylum Arthropoda

• As arthropods grow, they moult or shed exoskeleton and grow a new one.

• Respiration• Gills evolved in aquatic arthropods.• Tracheae developed in terrestrial arthropods.

• Circulation• Open circulatory system.• Blood cavity directly bathes internal organs.

Phylum ArthropodaClass Arachnida

• Includes scorpions, spiders, mites and ticks.

• Cephalothorax: head fuses to thorax.

• 4 pairs of legs:• The first pair may serve sensory function• Used for feeding, defense and locomotion

Phylum Arthropoda

Class Crustacea• Includes shrimp, lobsters, crayfish and

crabs.• Three body segments:

• Head, Thorax, Abdomen

• Paired appendages attach to each segment.• Two pairs of antennae• Feeding appendages• Appendages for moving

Phylum Arthropoda

• Feathered gills increase surface area for gas exchange.

Phylum Arthropoda

Class Insecta• 1.5 million species.• Three body segments:

• Head, Thorax, Abdomen

• Antennae on head sense environment.• Three pairs of walking legs on thorax.• Respiration:

• Air sacs and trachea that extend from external openings to tissues.

Phylum Arthropoda

• Flying Insects: Two pairs of stiff wings attached to thorax.

• Flies: One pair of wings.

• Beetles: Front wings form hardened wing covers.

Phylum Arthropoda

Growth and Development:

• Body plan stays the same as the animal develops.

• Metamorphosis• Body plan changes as the animal develops.• Change in diet lowers competition between

larvae and adults.

Phylum Arthropoda

•

Complete metamorphosis in ants. Incomplete metamorphosis in

dragonfly.

Phylum Arthropoda

Class Diplopoda and Chilopoda• Diplopods are millipedes.

– Each body segment has two pairs of legs.

• Chilopods are centipedes.– Each body segment has one pair of legs.

Both have up to 100 pairs of legs.

Phylum Arthropoda

Sources

• http://www.afsc.noaa.gov/RACE/media/photo_gallery/invert_files/Sidestriped_shrimp.htm

• http://quinnell.us/personal/carlin/journal/lobster.html• http://www.teridanielsbooks.com/States/Hawaii.htm• http://www.foodsubs.com/Shelfishcrab.htm• http://www.treknature.com/gallery/North_America/

photo60786.html• http://www.amonline.net.au/insects/insects/

metamorphosis.htm#insect

Plenary