Question: what is the difference between a sea slug and a sea cucumber?
Answer: The major difference between a Sea Slug and a Sea Cucumber is their phylum in the classification system. They're both in kingdom Animalia but Sea Slug is a Mollusc while Sea Cucumber is an Echinoderm. Molluscs are known by their soft skin. ... Sea Cucumbers can eject a major part of their body organs as a form of defence.