Do decapod crustaceans have nociceptors for extreme pH?
BACKGROUND
Nociception is the physiological detection of noxious stimuli. Because of its obvious importance, nociception is expected to be widespread across animal taxa and to trigger robust behaviours reliably. Nociception in invertebrates, such as crustaceans, is poorly studied.


RESULTS
THREE DECAPOD CRUSTACEAN SPECIES WERE TESTED FOR NOCICEPTIVE BEHAVIOUR: Louisiana red swamp crayfish (Procambarus clarkii), white shrimp (Litopenaeus setiferus), and grass shrimp (Palaemonetes sp.). Applying sodium hydroxide, hydrochloric acid, or benzocaine to the antennae caused no change in behaviour in the three species compared to controls. Animals did not groom the stimulated antenna, and there was no difference in movement of treated individuals and controls. Extracellular recordings of antennal nerves in P. clarkii revealed continual spontaneous activity, but no neurons that were reliably excited by the application of concentrated sodium hydroxide or hydrochloric acid.


CONCLUSIONS
Previously reported responses to extreme pH are either not consistently evoked across species or were mischaracterized as nociception. There was no behavioural or physiological evidence that the antennae contained specialized nociceptors that responded to pH.
Puri
Sakshi
S
Department of Biology, The University of Texas-Pan American, Edinburg, Texas, United States of America.
Faulkes
Zen
Z
D000818:Animals; D003400:Astacoidea; D001522:Behavior, Animal / Q000187:drug effects; D001566:Benzocaine / Q000494:pharmacology; D003445:Crustacea; D033364:Decapoda / Q000502:physiology*; D006851:Hydrochloric Acid / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D009619:Nociceptors / Q000502:physiology*; D033541:Palaemonidae; D012972:Sodium Hydroxide / Q000494:pharmacology
D012972:Sodium Hydroxide; D006851:Hydrochloric Acid; D001566:Benzocaine