the worms phylum platyhelminthes phylum nemertea phylum nematoda phylum annelida
TRANSCRIPT
The Worms
Phylum PlatyhelminthesPhylum NemerteaPhylum NematodaPhylum Annelida
Bilateral Symmetry
• One way to cut and get 2 identical halves
• Front (anterior) and rear (posterior)• Back (dorsal) and belly (ventral)• More active in pursuit of prey
Platyhelminthes - Flatworms
• Dorsoventrally flattened• Simple Central Nervous system• Muscular system, Reproductive
system - True organs• Singular opening for gut
20,000 Species of Flatworms• Turbellarians - Free-living
carnivores, seen most in marine habitats
• Flukes (Trematodes) – largest group, parasites
• Tapeworms (cestodes) – live in intestines.
Ribbon Worms (Nemertea)
• Sac Gut digestive tract (mouth, gut)
• Circulatory system/Hermaphrodites
• Proboscis – used to entangle prey• Feed on worms and crustaceans
Nematodes (some – roundworms)
• Live in sediment or tissues of marine organisms (parasitic)
• Cylindrical body, pointed at both ends.
• Larva found in the flesh of many fish– Infection of humans from eating raw
or under cooked fish
Annelida – segmented worms• Includes earthworms and many
marine worms• Polychaetes – marine annelids.
– Each segment has parpodia with setae at the ends.
– Closed circulatory system– Most carnivores - Nereis
More Annelids
• Oligochaetes– Marine earthworms, found in mud and
sand
• Leeches (Hirudinea)– Most are freshwater – sucker at ends
Brachiopoda (not a worm)
• Lamp shell• Two valves,
dorsal and ventral• Lophophore,
unique feeding structure – like two ciliated, coiled arms
The Christmas Tree WormThe Christmas tree worm, Spirobranchus giganteus, is a Christmas tree-shaped serpulid tube-dwelling worm with magnificent twin spirals of plumes used for feeding and respiration. This cone-shaped worm is one of the most widely recognized sedentary polychaete worms.