1. Unit 3 Chapter 12 Invertebrates (6 classes)
12.1 Most Animals are invertebrates (ex:sponges)
12.2 Cnidarians and Worms
12.3 Mollusks and Echinoderms
12.4 Arthropods

2. 12.1 Invertebrates are diverse
Invertebrates = Animals without a backbone (spine) or bone tissue
Live almost everywhere
Most are small (exception = giant squid can be 59 feet, 992 lbs.)
There are six groups
1-Sponges 4-Mollusks
2-Cniarians 5-Echinoderms
3-Worms 6-Arthropods

3. 12.1 Sponges Simplest multicellular animal on earth
Sessile Organisms (live attached to 1 spot & do not move)
Have no tissue; no organs
Most live in salt (some in fresh h20)
Have flagella to move water
Specialized cells that form walls, pores, filter out food and O2, digest food
Spicules (needlelike spines needed for shape)

4. 12.1 Sponge Reproduction Sponges reproduce asexually.
Buds form alongside the parent or break off and float away.
Sponges reproduce sexually
Sperm (and sometimes egg) cells are released into the water for fertilization
A fertilized egg becomes a larva (an immature form at an early stage) that is different from the parent.
They have changed little over time.

5. 12.2 Cnidarians & Worms Cnidarians: live in water
Central opening surrounded by tentacles
Ex: jellyfish, sea anemones, hydras (fresh water), and corals
Worms: live in water, land, inside organisms
soft, tube-shaped bodies, distinct head

6. 12.2 Cnidarians Feed on plankton, fish, clams
Many are Sessile (attached to 1 place)
Have stinging tentacles: fingerlike extensions of their bodies that reach into the water
Each stinging cell as a nematocyst or capsule that holds a barbed filament which releases poison into prey

7. 12.2 Cnidarians continued
Body made up of flexible layers of tissue organized around a central opening which both takes in food and releases waste.
Though sessile, they can move their muscles (bend, extend tentacles, swim, etc.) to catch prey
Have a simple nervous system

8. 12.2 Cnidarian Reproduction
They need water to reproduce
Sexual –
Sperm carried to eggs in water
Fertilization makes a “larva”
Asexual
Buds are produced on parent plant
Carried away by water

9. 12.2 Jellyfish Life cycle includes several stages
Body or form of jelly fish is different for each stage
Adult female medusa releases fertilized eggs
Free swimming larva settle on bottom
Polyp’s form on ocean floor
Disks begin to form & later separate
Disks mature into a new medusa

10. 12.2 Different body plans Body Plan = shape of an animal’s body
Radial symmetry – organized around a central point or mouthlike opening leading into gut (jellyfish)
Can capture food from any direction
Bilateral symmetry – Both halves are equal & has 1 line of symmetry
Moves forward head first; good plan for mobile animals (butterfly, worm, human)

11. 12.2 Worms
Worms have simple bodies, but complex body systems: digestive, excretory, nervous, circulatory & muscular systems are found in worms
Take in oxygen & water thru skin, dirt thru mouth
Reproduce sexually & asexually; no distinct male/female worms; have both reproductive structures
Segmented Worms: divided into individual compartments or segments (annelids or “ringed” animal)

12. 12.2 Worms Continued Flatworms – Roundworms – found everywhere
Have simplest bodies
Some move with cilia
Absorb nutrients thru their skin (tapeworm)
Roundworms – found everywhere
More complex body structure
Muscles, nervous & digestive systems
Important decomposers on land/water

13. 12.3 Mollusks & Echinoderms
Soft bodied
Many have protective shell
Can live on land, salt water, fresh water
3 groups: bi-valves, gastropods, cephalopods

14. 12.3 Mollusks continued
Have well-developed organ systems (muscles, digestive, respiratory, circulatory, and nervous systems)
Reproduce sexually with distinct male & female organisms
All have a muscular foot to which its head is attached.
All have a mantle or layer of folded skin that protects internal organs.
Ex: Oysters, clams, snails, mussels, octopi, squids, slugs
Snails are gastropods (“belly foot”)

15. 12.3 Bi-Valve Mollusks Have hard shell w/two matching halves
When shell closes, body is completely enclosed and protected
Body = a mass of tissue; no distinct head, but do have mouth and sensory organs plus gills to filter 02 and food.
They are filter feeders
Ex: Clams, mussels, scallops and oysters

16. 12.3 Gastropods Most diverse of mollusks
Many are protected by spiral shaped shells, live on land (have lungs) or water (have gills)
Head located at end of foot. Head has eyes and tentacles for sensing
Many have cutting mouths (radula)
Some eat animals, but most eat plants/algae
Ex: Snails, slugs, conches, whelks, periwinkles

17. 12.3 Echinoderms Live in the ocean Have radial symmetry
Bottom feeders w/mouth at center
Some are predators (eat clams/snails, etc.)
Echinoderm means “spiny skinned.”
Skeleton made up of stiff hard plates, but they have no bones
Some flexible (sea star); some stiff (sand dollars)
Ex: Sea stars, sea urchins, sea cucumbers, & sand dollars

18. 12.3 Echinoderms cont.
They have a unique water vascular system – water-filled tubes that radiate out from the center of their body.
At the base of these tubes are tube feet. At the top of each tube is a muscle which can close off the tube and create suction.
Tubes can then help with movement, or hunting or disabling prey.
Examples: Starfish & Sea Urchins

19. 12.4 Arthropods
Arthropods = invertebrate (iv) that has a segmented (jointed) body covered with a hard outer skeleton (exoskeleton).
Most iv’s are arthropods (more species than any other animal class)
¾ of all animal species are arthropods
First appeared on land 420 million years ago (about same time as plants)

20. 12.4 Arthropods - Exo – skeletons & Jointed Parts
Most live on land; some in water
Ex: Insects, crustaceans = shrimp, arachnid/spider, scorpion)
Exoskeleton = strong outer covering made of material called chitin which keeps cells, organs from drying out.
Joints = places where exoskeleton is thin and flexible (body, legs, antennae, claws) to which muscles attach for movement
Body typically has 3 sections: head, thorax (middle), and abdomen
Molting = shedding of exoskeleton for growth; leaves animal vulnerable to prey during molt.

21. 12.4 Complex Body Systems
Nervous (brain), digestive (stomach & intestine), circulatory (heart but no blood vessels)
They reproduce sexually with distinct male or female reproductive system
thorax
antennae
abdomen
head
Jointed
legs

22. 12.4 Insects = 6 legged 700,000 species.
Insect = arthropod that as an adult has 3 body segments (head, thorax, abdomen), 2 antennae, 6 legs attached to thorax (middle).
Most live on land; & are everywhere!
Obtain O2 through spiracles, small openings in their exoskeletons

23. 12.4 Insects Great diversity in appearance (color, shape, etc)
Many have compound eyes and
Antennae (sensory organs)
Many fly with 1 or 2 pairs of wings
Many are herbivores
Some are “social” like ants/bees and must live in groups to survive.

24. 12.4 Insects -
Reproduce sexually with female laying the eggs (many eggs!)
Metamorphosis = “change” - Insects undergo a life cycle process in which their appearance and body systems may change dramatically.
Complete metamorphosis has
3 stages: 1.larva 2. pupa 3.adult

25. 12.4 Insects Not all insects go thru complete metamorphosis.
Simple metamorphosis: only 2 stages: usually egg to adult form, (but smaller in size).
Larval form = caterpillar stage

26. 12.4 Crustaceans Most live in water and some on land.
Tiny krill and copepods are important food source in the oceans
3 or more pairs of legs, 2 pairs of sensory antennae
Some have gills; most have circulatory system but no blood vessels
Reproduce sexually from eggs
Some are herbivores, some carnivores; many are scavengers

27. 12.4 Crustaceans Can be sessile (barnacles) or mobile
Crustaceans include: shrimp, lobster, crab, barnacles, krill, copepods (ocean)
pill bugs (land)

28. 12.4 Arachnids = 8 legged Includes spiders, mites, ticks, & scorpions
4 pairs of legs; 2 body parts
no antennae
Exoskeleton; Jointed Legs

29. 12.4 Arachnids cont. Some are parasites (ticks, chigger mites)
Some are predators (spiders, scorpions) and have venom.
Spiders are largest group
Spiders and silkworms have spinnerets to produce silk
Most obtain O2 through spiracles
Some spiders have “book lungs” in their abdomen.

30. 12.4 Millipedes and Centipedes
Long, segmented bodies & many legs in pairs on each segment.
Millipedes …
have 2 pairs of legs per segment
move slowly & eat decaying plant matter
Centipedes …
have 1 pair of legs per segment
Move quickly & are predators
Have antennae and jaws & some have rear pincers