Download ZOO 115 Invertebrate Zoology

ZOO 115 Invertebrate Zoology
Phylum Sipuncula
Phylum Sipuncula - General
Characteristics
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“Peanut worms”
~ 250 species
Similar to Annelids but
NO segmentation
All marine – mostly
shallow water
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Usually burrow in mud
or sand but some
crawlers
http://www.ucmp.berkeley.edu/sipuncula/sipunculids_big.jpg
Phylum Sipuncula - external
anatomy
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Two main body
parts
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http://www.calacademy.org/research/izg/SFBay2K/peanutworm.htm
Trunk
Introvert
Tentacles
 Often have
hooks
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http://www.calacademy.org/research/izg/SFBay2K/peanutworm.htm
http://www.calacademy.org/research/izg/SFBay2K/peanutworm.htm
http://www.gulfspecimen.org/PhylumSipuncula.html
Phylum Sipuncula – Internal
Anatomy
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Spacious coelom
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Introvert
extended
by
Contraction
of circular
introvert
squeezing
body which
retractorsaround
muscles
while
fluid
forces
fluid
into it and
relaxing
filled
compensation
circular
sac
extending
it to fill
musclesfluid
causes
brings
introverttentacles
hollow
back intoand
trunk
extend them
http://bio.classes.ucsc.edu/bio136/sipuncula/sipuncula.html
Pressure from circular muscles
Phylum Sipuncula - Locomotion
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Hydrostatic skeleton (coelom)
Burrowing – sediment
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Peristalsis
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circular contract and longitudinal relax
Also use introvert
Burrowing – hard substrate
use secretions from epidermal glands
 spines
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Phylum Sipuncula - Feeding and
Digestion
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Most detritivores
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Direct Deposit feeders
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mucus and cilia on
tentacles
use introvert and
shortened tentacles
Suspension feeders
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mucus and cilia on
tentacles
Phylum Sipuncula - Feeding and
Digestion
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Mouth
Some take up nutrients
directly through body
Dorsal Anus
wall
Mouth at end of
introvert with muscular
pharynx
U-shaped digestive
tract – esophagus and
intestine
http://www.ucmp.berkeley.edu/sipuncula/sipunculids_big.jpg
Phylum Sipuncula –
Excretion/Osmogregulation
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Anus – solid waste
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Metanephridia
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one pair
Fairly resistant to
osmotic stress
Phylum Sipuncula – Nervous
system
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Nervous system
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Paired cerebral ganglia
Ventral nerve cord
Sense organs
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Tactile throughout body
but concentrated on
tentacles
Many have nuchal organs
(chemosensory) on
introvert
Phylum Sipuncula - Respiration
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Rock borers and burrowers in lowoxygen sediments
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Burrowers in oxygen-rich sediments
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Use tentacles
Use whole body surface
Tentacles and introvert
Some have special coelomic
channels for gas transport
Phylum Sipuncula – Reproduction
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Reasonable regenerative powers
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Some use fission and regeneration to reproduce
asexually.
Sexual
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Dioecious
Gametes released and mature in coelom
Gametes transferred and stored in nephridia until
released.
Male spawn triggered by environmental. Female
spawn triggered by sperm in water
Phylum Sipuncula –Development
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Cleavage – Spiral and holoblastic
 have some cleavage patterns in common with
molluscs.
Some direct developers
Some indirect developers
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trochophore larvae
Some with pelagosphera larvae