single band from rRNA from brachionus sp.

[paco]

We are using a phenol:Chloroform method for RNA extraction always for plants. 
We tried to apply the same method for RNA extraction from brachionus, related 
with C. elegans. The results were good: we obtained a lot and good RNA, 
but...only appears a single band of rRNA with the same weight of 16S rRNA.  
Degradation can be discarded: absorbance and gel running showed us.

Please, can someone out here give us an explanation for this????.

Thanks in advance.