Thousands of long noncoding RNAs (lncRNAs) have been found in vertebrate 
animals, a few of which have known biological roles. To better understand the 
genomics and features of lncRNAs in invertebrates, we used available RNA-seq, 
poly(A)-site, and ribosome-mapping data to identify lncRNAs of Caenorhabditis 
elegans. We found 170 long intervening ncRNAs (lincRNAs), which had single- or 
multiexonic structures that did not overlap protein-coding transcripts, and 
about sixty antisense lncRNAs (ancRNAs), which were complementary to 
protein-coding transcripts. Compared to protein-coding genes, the lncRNA genes 
tended to be expressed in a stage-dependent manner. Approximately 25% of the 
newly identified lincRNAs showed little signal for sequence conservation and 
mapped antisense to clusters of endogenous siRNAs, as would be expected if they 
serve as templates and targets for these siRNAs. The other 75% tended to be more 
conserved and included lincRNAs with intriguing expression and sequence features 
associating them with processes such as dauer formation, male identity, sperm 
formation, and interaction with sperm-specific mRNAs. Our study provides a 
glimpse into the lncRNA content of a nonvertebrate animal and a resource for 
future studies of lncRNA function.