Download Reproductive

Phylum Platyhelmenthes (the flatworms)
General characteristics
Eumetazoa - animals with tissue
– Bilateria - have bilateral symmetry
Head end-cephalization
Tail end
Right and left side
Top (dorsal) and bottom (ventral)
triploblastic -ectoderm, mesoderm, endoderm.
Protostomia - a group of animals whose mouth
develops from the blastopore, and the mesoderm
forms from an area near the blastopore.
Acoelomata - They have a true mesoderm which fills the
original blastocoel between the outer epidermis and
digestive tract.
Integumentary- Rhabdites and one cell layer
epidermis in Turbellaria and usually ciliated;
syncytial tegument in other classes.
Skeletal - hydrostatic
Muscle - longitudinal, transverse, and circular
muscles are present.
Digestive - incomplete with intracellular and
extracellular digestion; no system in Cestoda.
Excretory - flame cells, or excretory tubes in
Cestoda.
Respiratory - no system, diffusion
Circulatory - none, diffusion.
Nervous - anterior ganglia, ventral ladder-like
system (two lateral cords with transverse cords).
a bilobed anterior ganglial mass (brain)
Protonephridia-a series of flame cells
that aid in excretion
Endocrine - hormones produced by nervous
system
Reproductive - monoecious in most
Well developed reproductive organs, mostly
internal fertilization.
Two of the parasitic classes have complex life
cycles
Trematoda Cestoda -
Class Turbellaria~5000 species, mostly free-living
~Dugesia- free living planarian
Branched gut
Reproductionasexual- fission
sexual - monoecious
Diversity-land planarian- Bipalium
Gone fission
Branched gut
eyespots
Class Trematoda--flukes
~parasitic
endoparasitic
ectoparasitic
~tegument=body wall
~suckers
~feed on host cells, tissue fluids, mucus (yuk!) and blood
~life cycle
monogenic flukes
digenic flukes
Opisthorchis - Human liver fluke
Schistosoma --- swimmer’s itch
Class Cestoda = tapeworms
Proglottids-
Head-scolex
Scolex
proglottid
Proglottid- note interconnection
Scolex
Life cycle
Phylum Nemertina- ribbon worms
Proboscis can be extruded to capture food
General characteristics~tube within a tube body plan- a complete digestive tract
~Acoelomate
~eversible proboscis, within a rhinocoel above the gut
~feeding-stylets and toxins
~closed circulator system, a single dorsal vessel with two lateral
vessels
~paired lateral longitudinal nerve cords
~asexual reproduction by fragmentation
~sexual reproductiondioecious
free-swimming larva in some marine species
Advanced Features~anus
~closed circulatory system
~dorsal nerve cord in some
~complex excretory system in close association with circulatory system
~mesodermally derived blood vessels & mesodermally lined
rhinocoel may provide links to higher phyla