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How many neurons does a crab have? 

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These results suggest that C. granulatus is a bimodal breathing crab, active both in water and air.
The results in the horseshoe crab show a strong similarity to the data from Cupiennius (8).
Since prior studies have located only retinal in the eyes of crabs, retinal may serve universally as a chromophore in crab visual pigments
We conclude that the blue crab has four genes that encode different MTs.
The model provides indirect support for conclusions of an earlier study that suggested Asian Shore Crab dominance was achieved through predation on juvenile recruits of resident crabs such as Carcinus maenas (Green Crab).
A field experiment showed that this was not necessarily due to a decrease in the availability of polychaetes near the crab burrows.
It is likely that serotonin is a neurotransmitter in the brain, but not in the lateral eye of the horseshoe crab.
These data show that the gastric and pyloric networks in the crab are not separate groups of neurons that independently generate two different rhythmic behaviors.
It has been suggested that serotonin serves as a neurotransmitter in the horseshoe crab, Limulus polyphemus.
Our results indicate that visual memory in the crab, and possibly other arthropods, including insects, is accounted for by functional changes occurring in neurons originating in the optic lobes.
From the available literature, it is evident that these immunostimulants have a major role to play in crab culture.
These results along with the histochemical controls eliminate the possibility that some molecule found in histaminergic neurons accounted for the AChE staining but support the possibility that acetylcholine might be involved as a neurotransmitter in lateral inhibition in the horseshoe crab retina.

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