1. INVERTEBRATES:
They don’t have back-bone : they don’t have internal skeleton (p59)
- Most primitive animals are in this group
- Some groups have body protection such as shells or external skeletons
- Some groups have jointed legs

2. Most Primitive animals
Body protected with an exoskeleton
Jointed legs
Poriferans
Cnidarians
Worms
Molluscs
Arthropods
Echinoderms
Poriferans
Cnidarians
1- Acuatic animals
2- No symetry/radial symetry
3- Full of pores
1- Acuatic animals
2- radial symetry
-bag-like shape
-Umbrela shape
3- Tentacles
Nutrition function
Interaction function
Reproduction
- No complex systems
- Filter feeders (choanocytes)
- Attached to a substrate
- Body supported structure:
Needle-like structures: spicules
Asexual reproduction by
budding
Nutrition function
Gastrovascular cavities (mouth)
Interaction function
- Coral and Hydrae attached to a substrate
- Tentacles full of cnidocytes with a thread
Reproduction
Asexual reproduction by
budding

3. Poriferans
Cnidarians
Worms
Molluscs
Arthropods
Echinoderms
Most Primitive animals
Body protected with an exoskeleton
Jointed legs
Flat-worm
Worms
Platyhelminthes
flat-worm:
tapeworm
Plannarians
1- Acuatic /Parasits / terrestial
2- bilateral symetry
3- long and have soft bodies
Interaction function
Reproduction
Nutrition function
- Digestion/circulatory/excretory
simple systems.
- Cutaneous respiration
Round-worm:
Nematodes
- Parasits
Regenerate part of their bodies
They move in the earth by little hairs
Annelides
ring-worm:
Earth-worm
- Sexual reproduction: Hermaphrodites
- Asexual reproduction: fragmentation

4. Poriferans
Cnidarians
Worms
Molluscs
Arthropods
Echinoderms
Most Primitive animals
Body protected with an exoskeleton
Jointed legs
Molluscs
Gastropods (Snails, slugs, limpets)
Shell: spiral shape
Radula: Mouth
*herbivorous
1- Acuatic or terrestial
2- bilateral symetry
3- they have a protective shell
Parts of the body organized for
vital functions:
Bivalve (mussels, clams, oysters)
Shell: 2 valves
* Water filters
Head – sense organs for
Interaction function
Muscular food – moving,
digging or catching prey
(interaction function)
Visceral mass – organs for
nutrition function and sexual
reproduction (hermaphrodites or have both different sex)
Chephalopods
(Internal Shell,
Tentacles and
mandible)
*carnivorous

5. Most Primitive animals
Body protected with an exoskeleton
Jointed legs
Poriferans
Cnidarians
Worms
Molluscs
Arthropods
Echinoderms
Arthropods
Singularities regarding their vital functions
Nutrition function
Interaction function
Reproduction
2- bilateral symetry
3- bodies protected with exoskeleton
4- Jointed appendages
1- Aquatic/ terrestial / adapted to fly
Excretory system: Malpighian tubes
Respiratory system: tracheae (internal tubes ending in a operture)
Parts of the body organized for
vital functions:
Head --- Thorax --- Abdomen
Simple or Compound eyes
Head
trunk
Cephalothorax
--- Abdomen
Oviparous and some undergo
Metamorphosis (they molt their exoskeletom)
(complete or incomplete)

6. Most Primitive animals
Body protected with an exoskeleton
Poriferans
Cnidarians
Worms
Molluscs
Arthropods
Echinoderms
Jointed legs
Arthropods
Jointed legs
Apendages related
to their mouth
Number of pair of legs
3 pairs
Repetitions of 1 or 2 pair of legs
At least 5 pairs

7. the body is organized regarding its unique AMBULACRAL SYSTEM:
Most Primitive animals
Body protected with an exoskeleton
Poriferans
Cnidarians
Worms
Molluscs
Arthropods
Echinoderms
Jointed legs
Echinoderms
1- Marine animals. Present at different depth levels
2- radial symmetry and many different shapes
3- their exoskeleton is under a thin cell layer
the body is organized regarding its
unique AMBULACRAL SYSTEM:
Usefull mainly for the interaction function:
For moving/ to breathe/to catch food
Ambulacral system

8. How sponges eat
Cnidocytes in Jellyfish
Snails moving through a knife
Metamorphosis