Skeletal development in Phaeodarians

Mon Sep 12 21:21:27 EST 1994

While working on the taxonomic history of silicoflagellates I found, 
from consulting Haeckel's Challenger reports that he had classified 
them among the phaeodaria, mistakenly assuming that whole 
silicoflagellate skeletons represented spicules from the calymma of a 
typical phaeodarian, such as "Cannorrhaphis". This idea is 
exemplified by Pl. 101 fig. 10 in the Atlas, showing "Dictyocha 
stapedia" which is actually a specimen of Phaeodina tripylea with a 
whole lot of epiodontiform Dictyochas stuck on the surface. Had it 
been feeding on them? Looking further into his account it seemed to 
me that he presents a number of different phaeodaria with silicious 
material stuck to the surface and that as with "Dictyocha stapedia" 
these may be acquired rather than productions of the phaeodarian cell 
itself. For example, are not the "cup shaped siliceous bodies, often 
with radial striations and with a thin solid wall" which supposedly 
characterise Catinulus Haeckel ACTUALLY valves of a centric diatom?

Has any work been done on how phaeodarians synthesise their 
distinctive skeletons? If they divide vegetatively they can hardly do 
this while the skeletons are intact, so do they dissolve them and 
then start afresh, gathering and dissolving diatoms or 
silicoflagellates or any other siliceous matter which is available 
and then reassemble new skeletons when they drop back to the deep 
sea? I'd be interested to know if anyone has looked into this.

Yours curiously,  Phil Parkinson, P.O. Box 11-696, Manners St P. O., 
Wellington, NEW ZEALAND and email as above.

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