Invertebrate chordates are animals that possess some characteristics of chordates but lack a backbone. They belong to the phylum Chordata and include groups like tunicates and lancelets. These organisms typically have a notochord, a dorsal nerve cord, and gill slits at some stage of their life cycle, which are key features of chordates. Unlike vertebrates, invertebrate chordates do not develop a bony spine. Tunicates, for example, are marine animals that often resemble sacs and filter feed through their gill slits. Lancelets are small, fish-like creatures that live in shallow waters and retain their chordate features throughout their lives.