Transcript The Worms - Bedford Public Schools

The Worms
Phylum Platyhelminthes
Phylum Nemertea
Phylum Nematoda
Phylum Annelida
Bilateral Symmetry
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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)
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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 Worm
The 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 coneshaped worm is one of
the most widely
recognized sedentary
polychaete worms.