31-IV DEUTEROSTOMIA Hemichordata	Select Chapter/Biodiversity TreeHomeBiodiversity Tree1. Physics2. Chemistry3. Astronomy4. Geology5. Cell Structure6. Molecular Biology7. Photosynthesis and Respiration8. Molecular Genetics9. Mitosis and Meiosis10. Mendelian Genetics11. Populations12. Communities13. Ecosystems14. Evidence of Evolution15. Theory and Process of Evolution16. Classification Systems17. Prokaryotes18. Eukaryota19. Viridiplantae (Plants)20. Embryophyta21. Tracheophyta22. Spermatophyta23. Magnoliophyta24. Fungi25. Metazoa (Animals)26. Eumetazoa27. Bilateria28. Coelomata29. Arthropoda30. Insecta31. Deuterostomia32. Chordata33. Vertebrata34. Teleostomi35. Tetrapoda36. Sauroposida37. Aves38. Mammals39. Western/Coniferous Forests40. Taiga (Northern Forests)41. Eastern/Deciduous Forests42. Tropical Forests43. Deserts44. Polar Environments45. Tundra46. Grasslands47. Wetlands48. Freshwater Environments49. Estuaries50. Marine Environments51. Extreme Environments
	Acorn Worm (Saxipendium coronatum) [© Allen, Chris] Chapter Outline Description of Deuterostomia Classification of Deuterostomia Echinodermata Hemichordata Sources Links to external sites will appear in pop-up windows.			The phylum Hemichordata contains two classes of Acorn Worms. These organisms have structures called stomochords, which were previously thought to be related to the notochord that defines the chordates in the following seven chapters, thus their name meaning "half chordates". Turns out, it's not related but likely happened through convergent evolution. Hemichordates are not observed often in iNaturalist; the most being eleven observations for any species as of 2024. CLASS ENTEROPNEUSTA Virginia Acorn Worm (Saccoglossus kowalevskii) - most iNat observations in the US for Hemichordata - 10 (Eastern U.S. coast, Chesapeake Bay to NYC) Yellow Acorn Worm (Ptychodera flava) CLASS PTEROBRANCHIA ORDER CEPHALODISCIDA ORDER RHABDOPLEURIDA Resources: Hemichordata - Chris Cameron, University of Victoria Hemichordata [ Previous Page ] [ Next Page ]