I checked out a few books and here are some random notes I felt were worth repeating here.
First of all the species family is Deapoda-Reptania-Anomuran-Paguroidea
From Invertebrate Zoology by Robert Barnes:
The abdomen twist has adapted for right spiral shells but left spiral can be used.
There are appendages on the tip of the abdomen called uropods. The left uropod is used for hooking to the columella of the shell.
The excretory pore is above the mouth, it is a small antenna connected to the bladder. I have a image on one of my crabs where I think you can see this but I need to confirm it first.
In some hermit crabs, the male will grab the shell of a female who is preparing to lay eggs and drag her around until she is ready. The eggs are attached to her pleopods with a cementing material secred by glands on the uropods and on the abdominal pleura. The glands may be on the ventral surface of the abdomen.
The female’s abdomen is lifted considerable to permit brooding of the eggs. Newly laid eggs appear as a bright orange mass, sometimes called a sponge.
Zoea are hatched and liberated when the female returns to the water.
Red, yellow and blue coloring are all carotene derivatives.
The x-organ sinus gland produces 3 hormones which indirectly control molting (ecdysis) via another hormone secreted by the Y-organ.
These hormones:
Regulate the length of inter molt
Accelerates pro-ecdysis stage
controls the amount of water taken up during ecdysis
During premolt or pro-ecdysis there is a continuing accumulation of food and a rise in blood calcium.
I’m not entirely sure this is completely accurate since some of the information in her book was questionable. For instance, depicting that you should tap the shell with a SPOON to make the crab come out. RME
Hermit Crabs by Sylvia A Johnson
Females ready to mate exude a odor (pheromone or hormone accoring to some other sources).
The male may use his claw to stroke or tap his partners claw.
In a shell fight, one crab may bang its shell against the victims shell to drive them out.
Evolution and Adaptation of Terrestrial Arthopoda by John L. CLoudsley-Thompson
He mentions a airborne pheromone being released also.
Crabs can tolerate large quantities of copper because its stored in their exoskeleton.
The male sex organ is the gonopod. We already know the female sex organs are gonopores. The eggs are laid, fertilized and held within the females shell until they are ready to be hatched and released into the water.
A biology of crustacea by James Green
Woodlice will die fairly fast in dry air. I’m not sure how fast ‘fairly fast’ is and how this would relate to other parasitic mites on our crabs.
The Physiology of Crustacea by Waterman Vol II
He mentions “Internal turgor: if this is too high the body and appendages may become to stiff to move”
Now this could be applicable to post molt stiff joints. I couldn’t find a definition in his book for Internal turgor though.
I found the following biology definitions:
turgor
(physiology) The pressure within cells, especially plant cells, derived from osmotic pressure differences between the inside and outside of the cell giving rise to mechanical rigidity of the cells.
Turgor drives cell expansion and certain movements such as the closing or opening of stomata.
Turgor
The physical state of a cell with its maximum content of water before bursting, characterised by swelling of the cell via the vacuole of the cell shrinking and the cell wall / membrane stretching.
Turgor
(biology) the normal rigid state of fullness of a cell or blood vessel or capillary resulting from pressure of the contents against the wall or membrane.
So I take this to mean the internal pressure of the crab. Someone who understands this better should post a comment and explain some of this to me!!