1. Invertebrates
Chapter 28

2. Sponges (Phylum Porifera)
Body is made of pores that water enters through.
Has a large opening where water leaves.
Sponges are sessile (cannot move)
The lining of the internal cavity is made
of collar cells that act as sieves to trap
plankton and other food

3. Sponges (Phylum Porifera)
Sponges have a skeleton made of spicules.
A spicule is made of silica or calcium carbonate.
Can reproduce both sexually or asexually.
Asexual – pieces of sponges can regenerate
Sexual – (most are hermaphrodites) Sperm cells from one sponge enter another through pores.

4. Cnidarians Body forms: Medusa – free-floating, and umbrella-shaped
Polyp – tube like and attached to something
There are tentacles around the opening of the gastrovascular cavity.
They have stinging cells with a barbed harpoon used for defense and to spear their prey

5. Cnidarians Examples: Hydras
Jellyfish – sting prey with tentacles (some have toxins)
Sea anemones – polyp form, feed on fish, reproduce asexually
Corals – live in reefs, tough skeleton of calcium carbonate

6. Phylum Platyhelminthes (Flatworms)
Can be parasitic
Include:
Marine flatworms
Tapeworms – parasitic, attach to host’s intestines. Grow producing proglottids (rectangular body sections)
Parasitic flukes – have suckers to attach to host

7. Phylum Nematoda (Roundwoms)
Have a body cavity called pseudocoelom (fluid moved within this cavity)
One way digestive system
Some are parasites you find in dogs, others are free living hunters
Human parasites include:
Ascaris lumbricoides
Trichinella spiralis
Necator

8. Phylum Molluska Includes: Snails Slugs Oysters Clams Scallops
Octopuses
Squids
Found in marine, freshwater and terrestrial habitats

9. Phylum Molluska Characteristics: Bilateral symmetry
Foot – used for movement
Mantle – forms the outer layer of the body
Most have one or two shells
Radula – tongue-like organ found in the mouth

10. Phylum Molluska Most species have male and female individuals.
Some, though, are hermaphrodites (some species of slugs and snails)
Oysters and sea slugs can change from one sex to the other and back again

11. Phylum Molluska Gastropods Snails and sea slugs
Most have a single shell and a pair of tentacles on their head with eyes at the tip
Can secrete mucus from their foot to glide along
Can be herbivores or predators

12. Phylum Molluska Bivalves Most marine, some freshwater
Clams, oysters, scallops, mussels
Two-part hinged shell
Some use jet propulsion to move quickly
Most are filter feeders

13. Phylum Molluska Cephalopods
Squid, octopuses, cuttlefish and nautiluses
Body is made of a large head attached to tentacles
Tentacles have suction cups or hooks to catch prey
Most intelligent invertebrate
Some have color vision
Move via jet propulsion
Marine predators, feeding on fish, mollusks, crustaceans and worms

14. Phylum Annelida (Segmented worms)
Marine worms, earthworms, leaches
Have a primitive brain in an anterior segement
Have specialized organ systems
Bristles called setae on each segment

15. Phylum Arthropoda Named after their jointed appendages.
Includes: insects, spiders, scorpions, crustaceans
Segmented
Exoskeleton (the crunch you hear when you squish them)

16. Phylum Arthropoda Arachnids Spiders, scorpions, ticks, mites
Most are carnivores, inject their prey with enzymes to dissolve tissue

17. Phylum Arthropoda Insects Ants, mosquitoes, flies, bees, crickets
Largest group of organisms
Head, thorax, abdomen

18. Phylum Arthropoda Crustaceans
Crabs, lobsters, crayfish, shrimp, barnacles, water fleas and pill bugs
Major food source for humans
Barnacles are sessile as adults and they have hard plates used for protection. They are also hermaphrodites but typically don’t fertilize their own eggs

19. Phylum Echinodermata Spiny invertebrates that live on the ocean floor
Sea stars, brittle stars, sea urchins, sea cucumbers
Endoskeleton make of calcium
Radial symmetry
Water-vascular system – tubes filled with water connected to hallow tube feet

20. Phylum Echinodermata Sea stars – carnivores
Brittle stars – thin, branched arms for movement
Sea lilies and feather stars – very old, mouth located on the upper surface

21. Phylum Echinodermata
Sea urchins and Sand dollars – spines for protection, sometimes venom
Sea cucumbers – soft, no arms. Some are hermaphrodites. They trap food in the water with tentacles
Sea daisies – no arms

22. Invertebrate Chordate
Skeleton is completely internal.
A rod called the notochord develops along the back of the embryo
Pharyngeal pouches – later develop into gills in aquatic animals

23. Invertebrate Chordates
Tunicates – adults are sessile, hermaphrodites
Lancelets – found in shallow ocean water. Draw water through their mouth with cilia