functions of different animal coeloms

1
functions of different animal coeloms

• simple circulatory system
• increase in body size possible (follows from 1)
• storage area for organs, separates organs from
  gut
• independent growth of organs possible (e.g.
  coelomic space allows storage of gametes,
  seasonal reproduction enhanced)
• allows for developmental/physiological
  coordination via circulating hormones
• hydrostatic skeleton - burrowing!
• also allows for eversible mechanisms, such as
  annelid proboscis, and hence diverse feeding
  methods can evolve

2
one recent Metazoan phylogeny (molecular data)
NEMERTEA MOLLUSCA BRACHIOPODA BRYOZOA PHORONIDA
ANNELIDA ECHIURA POGONOPHORA SIPUNCULA CHAETOGNATH
A
PLATYHELMINTHES
from Ruiz-Trillo et al. (1999) Science 283
1919.
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Some polychaete families
Sabellid (feather-duster worm)
Polynoid (scale worm)
Nereid
http//tolweb.org/tree?groupAnnelidacontgroup A
nimalsdynnodeid2512javaOfftrue
4
Close-up of feather-duster worm (Polychaeta
Sabellidae) radioles
http//sorrel.humboldt.edu/els15/Zoo314.html
5
more polychaete families
spionid
http//www.personal.psu.edu/users/ a/l/aln142/char
acteristics.htm
terrebellid (spaghetti worm)
serpulid (Serpula vermicularis)
http//sorrel.humboldt.edu/ els15/Zoo314.html
6
Regeneration in the spionid polychaete, Pygospio
elegans
Gibson Harvey, Biol. Bull. 199 4149. (August
2000)
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Poecilogony (egg eating) in annelid larvae
Boccardia proboscidea (Polychaeta
Spionidae) setiger larvae eating their siblings
a typical polychaete setiger-stage feeding
larva
http//ace.acadiau.ca/science/biol/ GGIBSON/resear
ch.htm
http//www.microscopy-uk.org.uk/ mag/artmar99/poly
ch.html
8
Epitoky by stolonization in syllid polychaetes
From Franke (1999) Hydrobiologia 40239-55