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Sponges and
Cnidarians
©2008 susan anderson
Sponges
Adults do not usually move (sessile)
Take food into their bodies to digest.
One of the oldest living animals (540 million years)
Belongs to the phylum Porifora (has pores)
Can regenerate
Sponge Structure
Pores – where water enters
Collar Cells – help move water and catch
food.
Jelly like cells – help digest and distribute
food, carry wastes, form egg and sperm
Spikes/Spicules – in some, give support
Osculum – where water exits, sometimes
carrying the young.
Structure of a Sponge
Sponge Reproduction
Reproduce both sexually and asexually
– Budding
A new small sponge grows from the old
– Separate Sexes
Egg and sperm cells are created
Water currents carry the sperm cells that move in
through the pores of an egg-bearing sponge
Egg develops into a larva (immature form)
These larva swim through the water until it
attaches to something to grow into an adult
Cnidarians
Carnivores that use their stinging cells
(cnidocytes) to capture prey and protect
themselves.
Have specialized tissues
One of two body plans
– Polyp
– Medusa
Reproduce both asexually and sexually
Examples of Cnidarians
Jellyfish
Sea anemones
Coral
Hydra
Worms
Three major phyla
– Platyhelminthes (flatworms)
– Nematodes (roundworms)
– Annelida (segmented worms)
Simplest organisms with a brain
– Allows them to detect food, predators, and mates very
quickly and respond
Reproduction
– Both asexual and sexual
– Regeneration
Platyhelminthes
Most are parasites
Examples
– Tapeworms
– Planarians
Nematodes
Most are tiny and hard to see
Are found in most all moist environments
Carnivores, herbivores, and parasites
“Tube within a tube” digestive system
Examples
– Ascaris
– Hookworms
Annelids
Have bodies made up of many segments
Closed circulatory system
Parasites, herbivores, scavengers,
predators
Most live in burrows or tubes
Examples
– Leeches
– Sea floor worms
– Earthworms
Earthworm Structure
Bristles/Setae
Clitellum
Mouth
Esophagus
Crop
Gizzard
Intestines
Brain
Ventral nerve cord
Hearts
Blood vessels
Earthworm Structure