Underside and circulatory system of the Atlantic Horseshoe Crab (Limulus polyphemus)

The curious horseshoe crab (or king crab) is not actually a crab at all. It is an ancient member of the Chelicerata - more closely related to scorpions and spiders than any crustacean.

Note that the colors on the bottom illustrations only indicate a state of oxygenation and deoxygenation (red and blue, respectively), not the true color of the blood. Since horseshoe crabs utilize the copper-based hemocyanin to transport oxygen (as opposed to hemoglobin, in vertebrates), their blood is colorless or a light yellow when oxygenated, and a deep blue color when deoxygenated.

Of note - the mouth of the horseshoe crab is a jawless opening leading to a gizzard, between the legs on the underside of the body, and the book gills are located directly below them. The book gills, in addition to being used for blood gas exchange, are occasionally used for increased motility.

Images:

Top: Anatomy of underside and tail. From the John Reeves Collection, via scientificillustration. 1827.

Bottom: Circulatory system. Recherches sur l’Anatomie Limulus. M. Alphred Milne Edwards, 1873.

635 notes

Show

  1. giraffepiano reblogged this from akzoo
  2. smellyeyeball reblogged this from akzoo
  3. akzoo reblogged this from biomedicalephemera
  4. toasteroverlord reblogged this from biomedicalephemera
  5. bellemorte47 reblogged this from biomedicalephemera
  6. greeklilly reblogged this from biomedicalephemera
  7. dr-pepper-of-boneshire reblogged this from biomedicalephemera
  8. fuckyeahhorseshoecrabs reblogged this from biomedicalephemera
  9. flummoxingfog reblogged this from biomedicalephemera
  10. isgramor reblogged this from biomedicalephemera
  11. yuuanblr reblogged this from biomedicalephemera
  12. floresalbert reblogged this from scishow
  13. do-it-for-science reblogged this from scishow
  14. msndrs reblogged this from thenoraninja
  15. skakerman reblogged this from scishow
  16. mclovinpope reblogged this from scishow
  17. durango1414 reblogged this from scishow
  18. generalfish reblogged this from scishow
  19. art-books-food reblogged this from scishow
  20. scandal-in-belgayvia reblogged this from scishow
  21. katie1101 reblogged this from merverb