1. Simple Animals
L2 Biology

2. A breakdown of the animal kingdom reveals many phyla
Porifera - sponges
Cnidaria – jellyfish, coral
Platyhelminthes – flat worms
Nematoda – round worms
Annilida – segmented worms
Mollusca – clams, snails, squid
Echinodermata - starfish
Arthropoda – insect, spider, crustacean
Chordata – frogs,fish, humans
SIMPLE
ANIMALS

3. Cnidaria (formerly called Coelenterata)
All have stinging cells (cnidocytes)
Two body forms:
Medusa – like a jelly fish
Polyp – like a hydra
Radial symmetry
Have tentacles

4. Cnidarian Cnidocyte
Have you ever been stung by jellyfish?

5. Cnidarian Life Cycle – medusa and polyp alternate
egg
larva

6. JELLYFISH - MEDUSAS

7. Hydra
Hydroid
Polyp body form

8. Hydra on water plants

9. Hydra Anatomy mouth tentacles testis bud ovary Basal disc
Gastrovascular
cavity
ovary
Basal disc

10. Coral is actually a colony of polyps, most of which are the size of a single hydra – they just make a case around them for their home.

11. Here are a variety of anemones – polyp body form

12. - Platyhelminthes Have flat bodies Some are parasitic
Most are free-living

13. These are free-living flatworms
Planaria

14. Scolex – head with hooks and suckers
Tapeworms – the ultimate parasite – only highly developed system is its reproductive system - hermaphroditic

15. Phylum Nematoda - roundworms
Mouth – digestive tube – anus
Most free-living
Some parasitic
Look like threads in the
microscope

16. Some are parasitic to humans
Trichina
From undercooked pork
Causes severe muscle aches when larvae migrate from intestine to muscles
Filaria
Causes elephantiasis
No treatment
Carried by mosquitoes
Hookworm
Enters through soles of feet
Larvae in human feces
Causes fatigue – may cause physical and mental retardation if children have it

17. This lesion is caused by a nematode infestation

18. Elephantiasis
Caused by filaria – the worm blocks the lympatic vessels and the area swells with lymph. No treatment is available.

19. Phylum Annelida Segmented worms Includes earthworms and leeches
Most are free-living
Complex body with organ systems
hermaphroditic

20. Leech Earthworm

21. Earthworm Anatomy

22. Phylum Arthropoda Jointed legs Chitinous exoskeleton
Ventral nerve cord
Must molt to grow
Some undergo metamorphosis
Includes insects, crustaceans, spiders, millipedes and centipedes

23. Class Insecta Six legs May have wings Undergo metamorphosis
Varied mouthparts
Breathe using spiracles

24. Class Arachnida – 8 legs, no antennae, simple eyes, chelicerae,
scorpion
tick
Dust mites
spiders

25. CCrustacea – two body regions = cephalothorax most live in water

26. Millipedes and Centipedes

27. The End