23.1 Sponges, Cnidarians, and Simple Worms
Sponges:
> do not
move
> filter
water to obtain oxygen and food
> skeletons
made of spicules
> reproduce
sexually and asexually
Cnidarians:
> Examples:
jellyfish, hydras, corals, sea anemones
> Have
a gut open to the outside
> Have
tentacles with nematocysts (stinging cells)
> Have
2 life stages: polyp & medusa
Flatworms:
> Ex.
fluke, tapeworm
> Most
are internal parasites
> Can
regenerate asexually
> Can
also reproduce sexually; they are hermaphroditic (have male & female
reproductive systems)
Roundworms:
> Called
nematodes
> Most
are parasitic
> Most
reproduce sexually
> Some,
like Ascaris, can cause diseases in animals and humans
23.2 Mollusks, Annelids, and Arthropods
Mollusks:
> There
are 3 classes of mollusks:
Bivalvia clam, mussel, oyster
Gastropoda snail, slug; feed with a rough tongue called a radula
Cephalopoda squid, octopus, nautilus
> They
were the 1st animal to evolve nephridia to collect and discharge waste.
> They
have 3 basic body parts: head, foot, visceral mass.
> Their
soft bodies are covered by the mantle, which secretes the shell.
Annelids:
> segmented
worms
> Ex.
earthworms, leeches, marine worms (such as tube worms, clam worms, feather
dusters)
Arthropods:
> have
jointed appendages, a segmented body, and an exoskeleton made of chitin
> includes
insects, arachnids, crustaceans, centipedes & millipedes
23.3 Echinoderms and Chordates
Echinoderms:
> Ex.
starfish,
> Five-part
radial symmetry
> Have
a water vascular system to move their tube feet
> Are
deuterostomes
Chordates:
> at some
point in their lives, have a notochord, a dorsal nerve cord, and pharyngeal
slits
> 3 main
groups: tunicates, lancelets, vertebrates
> tunicates
lose their chordate characteristics as adults |