Flatworms Phylum Platyhelminth. Endoparasite Exoparasite / Ectoparasite.
Phylum Platyhelmenthes (the flatworms) General characteristics
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Transcript of Phylum Platyhelmenthes (the flatworms) General characteristics
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.
IntegumentaryIntegumentary- Rhabdites and one cell layer epidermis in Turbellaria and usually ciliated; syncytial tegument in other classes.
SkeletalSkeletal - hydrostatic
MuscleMuscle - longitudinal, transverse, and circular muscles are present.
DigestiveDigestive - incomplete with intracellular and extracellular digestion; no system in Cestoda.
Excretory Excretory - flame cells, or excretory tubes in Cestoda.
RespiratoryRespiratory - no system, diffusion
CirculatoryCirculatory - none, diffusion.
NervousNervous - 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 Endocrine - hormones produced by nervous system
ReproductiveReproductive - monoecious in mostWell developed reproductive organs, mostly
internal fertilization.Two of the parasitic classes have complex life
cyclesTrematoda -Cestoda -
Class Turbellaria-~5000 species, mostly free-living~Dugesia- free living planarian
Branched gut
Reproduction- asexual- fission sexual - monoecious
Diversity-land planarian- Bipalium
Gone fission
Branched guteyespots
Class Trematoda--flukes~parasitic
endoparasiticectoparasitic
~tegument=body wall~suckers~feed on host cells, tissue fluids, mucus (yuk!) and blood
~life cyclemonogenic flukesdigenic flukes
Opisthorchis - Human liver fluke
Schistosoma --- swimmer’s itch
Class Cestoda = tapeworms
Proglottids-Head-scolex
proglottidScolex
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 reproduction-
dioeciousfree-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