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02 June 2015 Annelida.ppt 1
Phylum Annelida
“segmented worms”
02 June 2015 Annelida.ppt 2
Phylum Annelida• Phylum Annelida
• Latin “ringed” analogy to tree annual rings
~ 9000 species
• Body plan •Tube-in-tube, Protostomous
•Bilateral symmetry
•Coelomate, “split” coelom
• Marine, aquatic, terrestrial
02 June 2015 Annelida.ppt 3
Phylum Annelida• Tissues and organs differentiated • Segmentation highly developed• Mesodermal “blocks,” each with own coelom
• Septa between segments
02 June 2015 Annelida.ppt 4
Phylum Annelida• Hydrostatic skeleton
• Fluid pressure in coelom provides support & locomotion
• Circular muscles
• Longitudinal muscles
• Peristaltic locomotion
02 June 2015 Annelida.ppt 5
Function of a hydrostatic skeleton
02 June 2015 Annelida.ppt 6
Phylum Annelida• Setae (“bristles”) of chitin• “anchors” for earthworm
• “paddles” for polychaete
• Enlarged as jaws in leeches, some polychaetes
02 June 2015 Annelida.ppt 7
Animal Life
• Ways the needs of cells are met• Food
• O2 and CO2 exchange • Across epidermis, some have “gills”
• Waste removal• Metanephridia in each segment
02 June 2015 Annelida.ppt 8
Phylum Annelida
• Special concerns of a multicellular animal• Circulation closed
• Coordination: Nervous system with paired ventral cords
• Structural support: Hydrostatic
• Movement: Hydrostatic
• Maintenance of water balance: Segmental metanephridia.
• Reproduction• Usually sexual, sexes separate or hermaphroditic
02 June 2015 Annelida.ppt 9
Phylum Annelida
• Closed circulatory system• Multiple “hearts”
• Hemoglobin • not in blood cells
• reddish-pink color
02 June 2015 Annelida.ppt 10
Phylum Annelida
• Central nervous system• Dorsal brain
• Pair of nerves on sides of esophagus
• Paired ventral nerve cords with paired ganglia in each segment
• Transverse nerves connect ganglia in each segment
02 June 2015 Annelida.ppt 11
Phylum Annelida
• Earthworms’ paired nerve cords are fused into single ventral cord
• Arthropod better illustrates primitive nervous system of both phyla.
02 June 2015 Annelida.ppt 12
Phylum Annelida
• Metanephridia for excretion of metabolic waste products
02 June 2015 Annelida.ppt 13
Phylum Annelida “Class Polychaeta”• Mostly marine, very
diverse (polyphyletic )
• “many setae,” clusters with 20+ setae
• parapodia
02 June 2015 Annelida.ppt 14
Phylum Annelida Superclass Errantia
• Mostly marine, diverse active swimmers, predators
• “many setae,” clusters with 20+ setae
• parapodia
02 June 2015 Annelida.ppt 15
Phylum Annelida
Superclass Sedentaria• Mostly marine,
sedentary tube builders, filter feeders
• Class (?) marine tube worms
• Class (?) Clitellata• With clitellum
02 June 2015 Annelida.ppt 16
Phylum Annelida
Class (?) Clitellata • Clitellum
• Aquatic & terrestrial
Subclass (?) Oligochaeta• Few setae in 2-4 clusters per
segment
02 June 2015 Annelida.ppt 17
Phylum Annelida
Subclass (?) Hirudinea• pair of bladelike “jaws”
• posterior “suction cup”
• Predators
• External parasites, “bloodsuckers”
• Secrete anticoagulants
• Medicinal use
02 June 2015 Annelida.ppt 18
Phylum Annelida
Class Hirudinea Hirudin from leech,
Hirudo medicinalis, inhibits blood clotting
H. medicinalis, registered as “medical device.”