The remaining animals, the Bilateria, are bilaterally symmetrical and triploblastic, with well-developed tissues and organs. They often have specialized immune cells. Most fall into two major lineages, the protostomes and deuterostomes. Among the protostomes, representatives of the molting clade (Ecdysozoa) have been most extensively studied in an immune context, as this clade includes nematodes and arthropods, both containing well-studied model organisms. Caenorhabditis elegans and other nematodes have reduced genomes and from an immunological perspective are surprising for what they do not have. Although C. elegans has one bonafide TLR that plays a role in defense against some bacteria (Tenor and Aballay, 2008) , it lacks Myd88, NF-κB and several other components of the canonical Toll pathway. NLRs are also lacking. Nonetheless, C. elegans can mount inducible, parasite specific responses. It has several novel signaling pathways for defense (Irazoqui et al., 2010) and produces many distinctive antimicrobial peptides (AMPs) for protection from bacteria (Roeder et al., 2010) . C-type lectins may serve as recognition molecules in C. elegans. The preoccupation with production of AMPs by gut cells reflects their diet of bacteria, which could include potential parasites (Roeder et al., 2010) .