Sponges cnidarians worms mollusks

Kingdom Animalia INVERTEBRATES: NO BACK BONE Sponges Cnidarians Flatworms Roundworms Mollusks

Sponges  Assymetrical: similar parts regularly arranged around a central axis  Freshwater or saltwater  Sessile – do not move  Filter feeders: filter food out of the water  Body covered with many pores (openings)

Sponges  All cells function independently  Some produce spicules: thin, spiny structures that form the endoskeleton  Some produce soft fibers as a skeleton  These are the ones people use

Sponge Reproduction:

 Asexually –budding  Sexually – joining of sperm and egg

Other Sponge Facts:  Sponges can regenerate – replace lost body parts through mitotic cell division.  Commercial sponge harvesting for personal care industry.  Used as medicines

Cnidarians – Stinging Animals  Radial Symmetry: similar parts regularly arranged around a central axis

 Hollow central cavity with 1 opening called a mouth

Cnidarians – Stinging Animals  2 body types:  Polyp: vase shape that doesn’t move 

Medusa: umbrella shape that moves around

Cnidarians – Stinging Animals  Mostly saltwater  Corals  Jellyfish  Sea anemones  Hydra

Feeding  Use tentacles to capture food.  Tentacles have NEMATOCYSTS – stinging cells that grab and immobilize prey using toxins.  Waste products and undigested materials are expelled through the mouth.

Organization  Nerve net – conducts impulses from all parts of the body.  No brain.  Two layers of tissues derived from endoderm and ectoderm

Cnidarian Reproduction  Asexually – budding (polyp form)

 Sexually –produces egg and sperm

Flatworms Platyhelminthes  Bilateral Symmetry: body the same on both sides  Acoelomate – no body cavity.

An Important Group  Free-living in freshwater or parasitic in a host  Many nasty parasitic infections. 

Dugesia

Tapeworms  Flukes 

Flatworm Feeding  Free living flatworms are scavengers.  Parasitic flatworms use specialized structures (usually with hooks) to attach to a host.

Flatworm Reproduction  Sexually - Hermaphrodites – internal fertilization.  Asexually – fission – when damaged, regenerates new body parts.

Roundworms - Nematoda  Bilateral Symmetry  Free-living in soil or parasitic in a host  Pseudomate – false body cavity.  Movement Longitudinal muscles produce a thrashing movement

Roundworm Feeding  Have a simple digestive system.  Have a mouth and an anus  Parasitic roundworms use specialized structures called hooks and suckers to attach to a host.

An Important Group  Many nasty parasitic infections in humans, livestock 

Pinworms, Ascaris, hookworms,

Trichinella

Segmented WormsAnnelida  Bilateral Symmetry  Body is divided into segments  Body covered with mucus to aid in movement  Have tiny setae (bristles) to pull it through the soil

Segmented WormsAnnelida  Have a closed circulatory system: all fluids are in tubes  Have a simple nervous system  Ex. Earthworm

MOLLUSKS  Soft bodied animals that have an inner and outer shell  They have a tube foot to:  Open and close their shell  Movement  Bury themselves in the sand

MOLLUSKS  They have a head with a sense organ (like an eye)  3 Groups separated by shell characteristics  Single or no shell  2- Shell  Tentacled

Single or No Shell Mollusks  Ex. Slugs and snails  Also called gastropods  Radula: tongue that’s used to get food

2-Shell Mollusks  Ex. Clams, oysters, mussels, and scallops  Also known as bivalves  Filter feed  If sand gets stuck for many years, it becomes a pearl

Tentacled Mollusks  Ex. Octopus, Squid, and nautiluses  Also known as cephalopods  Use tentacles to catch food