Phylum Annelida Segmented Worms Fireworm Feather duster worm Christmas tree worm Leech.
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Transcript of Phylum Annelida Segmented Worms Fireworm Feather duster worm Christmas tree worm Leech.
Phylum AnnelidaSegmented Worms
Fireworm
Feather duster worm
Christmas tree worm
Leech
Annelid Characteristics• Segmentation =
Metamerism– metameres
(=somites, segments)– Show true
segmentation - both internal and external
– Allows for specialization
Annelid Systems All systems found in Annelids but skeletal
• Complete digestive tract - some specialization - crop and gizzard
• Closed circulatory system - is segmentally arranged dorsal and ventral vessels aortic arches (hearts)
• Excretion – Nephridia -
segmentally arranged
Annelid Systems All systems found in Annelids but skeletal
• Nervous system– ladder shaped– pair of cerebral
ganglia– double ventral nerve
cords– pair of ganglia in
each segment– several sensory
structures• taste buds• tactile organs• eyes in some• statocyst
Annelid Systems All systems found in Annelids but skeletal
• Reproduction– some are monoecious, others dioecious– marine species have trochophore larvae– some have asexual reproduction by
• Budding
• fragmentation
Annelid Systems
• Respiration – across body surfaces
– some have gills
– some use parapodia
Annelid Systems
Class Polychaeta
• Make up 2/3 of phylum
• most primitive annelids; ancestral to other two classes
• almost all are marine, few freshwater species
Polychaet Characteristics
• differentiated head– Tentacles
– first segment• Prostomium
• Peristomium
• Mouth– Palps
– eyes
• Parapodia- lateral appendages– notopodium-
dorsal– neuropodium-
ventral– acicula- rods
• Respiration– By parapodia
Polychaet Characteristics
• Reproduction
– sexes separate
– no permanent gonads• egg and sperm form from coelomic peritoneum
• pass out of nephridia or burst thru body wall
• fertilization is external in sea
• free swimming larva- trochophore
Polychaet Characteristics
• free living- all are predators
• tube dwelling- all are filter feeders– secrete their own tube– burrow into substrate
Polychaet Ecological Types
Class - Oligochaeta
• Terrestrial or Freshwater
• No distinct head - but contains pro- and peri- stomium
• Clitellum - present at all times– Used in copulation– Cocoon production
Class - Oligochaeta• Reproduction
– Monoecious– Copulation– Internal fertilization– Eggs laid in cocoon– no larval stage
Class - Oligochaeta
• Digestive system - well differentiated– mouth
– pharynx
– crop
– gizzard
– intestine - Typhlosole
– Anus
Class - Oligochaeta
• Circulatory system– Closed
– 5 pairs of aortic arches
– Hemoglobin
• Respiration– Body surface
• Excretion– Nephridia
Class - Hirudinea
• Freshwater or terrestrial
• Have suckers
• Segmentation fixed (34 segments)
• Clitellum only during season
• Digestive tract– large crop
– Anticoagulant
• Medically important