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.

449 notes

Show

  1. caffinatedmess reblogged this from m0thlight
  2. m0thlight reblogged this from biomedicalephemera
  3. fabienneaudeoud reblogged this from historyishuman
  4. somestuffofinterest reblogged this from biomedicalephemera
  5. raiistmar reblogged this from biomedicalephemera
  6. levliberman reblogged this from scientificillustration
  7. thescientificgap reblogged this from biomedicalephemera
  8. whenimprocrastinating reblogged this from ichthyologist
  9. askbloodycancer reblogged this from cultofweird
  10. wolffeeder reblogged this from ichthyologist
  11. fallupthestairs reblogged this from ichthyologist
  12. christo-pho reblogged this from everythingisconnectednow
  13. everythingisconnectednow reblogged this from ichthyologist
  14. callofthemuse reblogged this from ichthyologist
  15. dannyd0rko reblogged this from ichthyologist
  16. flyingbeds reblogged this from pyreclaws
  17. amischiefofmice reblogged this from newfriendly
  18. newfriendly reblogged this from ichthyologist
  19. retributionisathand reblogged this from ichthyologist
  20. fiestafugitives reblogged this from ichthyologist
  21. pyreclaws reblogged this from ichthyologist
  22. marikosayshi reblogged this from ichthyologist
  23. reyairia reblogged this from ichthyologist and added:
    Turians, ladies and gentlemen. Just to show you that yes, Bioware did do some research. And that yes, the biology is...
  24. ichthyologist reblogged this from neuroconnoisseur
  25. neuroconnoisseur reblogged this from biomedicalephemera
  26. timothyreal reblogged this from unnaturalist
  27. lewinspage reblogged this from biomedicalephemera and added:
    coolest sea organism… well.. maybe...prehistoric buggers
  28. steinwaldwolf reblogged this from unnaturalist and added:
    Underside and circulatory system of the Atlantic Horseshoe Crab (Limulus polyphemus) The curious horseshoe crab (or king...
  29. insurmountablefears reblogged this from biomedicalephemera
  30. biologynerdynerd reblogged this from scientificillustration
  31. ihaveabignose reblogged this from yukidoll
  32. thecrackinsideyourfuckingheart reblogged this from yukidoll
  33. yukidoll reblogged this from unnaturalist