[File:BranchiostomaLanceolatum PioM.svg|thumb|500px| 1. brain like blister

  2. notochord
  3. dorsal nerve cord
  4. post-anal tail
  5. anus
  6. food canal
  7. blood system
  8. abdominal porus
  9. overpharynx lacuna
 10. gill's slit
 11. pharynx
 12. mouth lacuna
 13. mimosa
 14. mouth gap
 15. gonads (ovary/testicle)
 16. light sensor
 17. nerves
 18. abdominal ply
 19. liver like sack

]] The lancelets (from "lancet"), also known as amphioxus, comprise some 22 species of fish-like marine chordates with a global distribution in shallow temperate (as far north as Scotland) and tropical seas, usually found half-buried in sand. They are the modern representatives of the subphylum Cephalochordata, formerly thought to be the sister group of the craniates. In Asia, they are harvested commercially as food for humans and domesticated animals. They are an important object of study in zoology as they provide indications about the origins of the vertebrates. Lancelets serve as an intriguing comparison point for tracing how vertebrates have evolved and adapted. Although lancelets split from vertebrates more than 520 million years ago, their genomes hold clues about evolution, particularly how vertebrates have employed old genes for new functions. They are regarded as similar to the archetypal vertebrate form.