Although invertebrates are primitive organisms, they reveal enormous complexity in their immune systems and their biological functions. Although in the past only wet-lab methods were available to study the complexity of invertebrates, with the recent development of computational tools, it has been possible to study the invertebrate immune system in greater detail. In this chapter, we discuss the different computational tools used to study the complex immune system from sponges to molluscs. We also discuss use of computational tools in the study of molluscan sialic acid binding lectins (SABLs).