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Biology 222Invertebrate Zoology II
Fall 2004Stephen M. Shuster
Northern Arizona University
Lecture 12
Annelid SystematicsThree primary groups
a. Class Polychaetab. Class Oligochaetac. Class Hirudinida
“The Older Version”
Annelid SystematicsThree primary groups
a. Class Polychaetab. Class Clitellata
1. Subclass Oligochaeta2. Subclass Hirudinoidea
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Subclass HirudinoideaThree Orders:a. Order
Acanthobdellida1. Small groups, but
apparently ancestral.2. Posterior sucker only.3. Occasional parasite
on freshwater fish.
Class HirudinoideaThree Orders:b. Order Branchiobdellida1. Small group, single family2. Ectoparasitic on crayfish3. Occasionally placed with
oligochaetes.
Class HirudinoideaThree
Orders:c. Order
Hirudinea1.Considered
the “true leeches.”
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Order Hirudinea2. Two subordersa. Rhynchobdellae -
with proboscisb. Arhynchobdellae -
without proboscis.
Hirudinoid Reproduction1. Male and female reproductive
anatomy2. Like oligochaetesa. Hermaphroditismb. Differential allocation of energy to
sperm, ova (S>>O).c. Sex Allocation.
Hirudinoid Reproduction1. Usually with copulation 2. or occasionally with hypodermic
insemination
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HirudinoidReproductiona. Rhynchobdellae1. male and female
copulatorystructures
HirudinoidReproduction
b. Arhynchobdellae1. reduced female
structures2. vector tissue
Vector Tissue 1. Receives sperm
after hypodermic insemination.
a. Responsible for transporting sperm (or spermatophore) to ovaries
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Parental Care 2. Many leeches provide parental care
to younga. Broods are guarded and fed by the
parent.b. Some species for creches.
Baby Leeches with Mom/Dad
I thought I saw a forest rat
Which hopped just out of reach
I looked again, and saw it was
A giant sucking leach.
If that should come to dine, I thought
'Twould drink us all and each
Leech Poetry
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I took a leach to bed with me,
I fed it all night through,
But when by light I chanced to see,
I squashed it with my shoe.
Brush off your leaches, start bleeding right now,
Brush off your leaches, and the women you will wow.
Leech Poetry
Annelid Evolution
1. Annelids appear to be derived from ancestors that may have occupiedfreshwater or brackish environments
Annelid Evolutiona. Similar to polychaetes - had setaeb. Probably didn't arise from full
polychaetes because it would require loss of parapodia.
c. However, polychaetes have trochophore larvae.
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TrochophoreLarvae
1. Possessed by several coelomateprotostomes.
TrochophoreLarvae
1. Phylum Annelidaa. Class Polychaeta
2. Phylum Echiura3. Phylum Sipuncula4. Phylum Mollusca
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Annelid Evolutiona. Similar to polychaetes - had setaeb. Probably didn't arise from full
polychaetes because it would require loss of parapodia.
c. Possess specialized structures associated with copulation.
2. Seem to be ancestral to other clitellate worms (leeches).
1. Unique annelid head2. Parapodia3. Elaboration of
polychaete head.
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4. Hermaphroditism5. Clitellum6. Direct development7. Cerebral ganglion shift8. Reproductive anatomy9. Fixed segment number
10. Fusion of coelomiccompartments
11. Posterior sucker12. Superficial annuli13. Loss of chetae
Coelomate Worms1. Four Major Phylaa. Phylum Echiurab. Phylum Sipunculac. Phylum Pogonophorad. Phylum Vestimentifera
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Coelomate Worms1. Four Major Phylaa. Phylum Echiurab. Phylum Sipunculac. Phylum Pogonophorad. Phylum Vestimentifera
Are actually Are actually PolychaetesPolychaetes!!
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“Higher Protostomes”
“Higher Protostomes”
SipunculaMolluscaEchiuraAnnelida
ArthropodaTardigrada
Onychophora
“Higher Protostomes”
SipunculaMolluscaEchiuraAnnelida
ArthropodaTardigrada
Onychophora
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“Higher Protostomes”
SipunculaMolluscaEchiuraAnnelida
ArthropodaTardigrada
Onychophora
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“Higher Protostomes”
SipunculaMolluscaEchiuraAnnelida
ArthropodaTardigrada
Onychophora
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