Crabbie Eating Habits - Coloration

I'm just doing my own research on the topic of what hermie's eat in their native lands and what may contribute to color. I definately feel that I am missing something in my little friends diet due to the color changes that occur from the pet store to my home. For example, I've purchased ALL my E's that have an all over blue coloring to a wonderful blue-green tint to them. Now, after having them for a few months (up to 6 months) they are all a dark brown/tan with orangish highlights. So I wonder... what am I missing? Is it healthier for them to be brown or blue?

Not all my information is pertaining to land hermit crabs... and especially E's because that specific of information is difficult to locate. Also I am NOT an expert by ANY means in biology, ecology, marine, etc... this is just me being curious and gathering information. Like a research paper... sorta... :)

First of all I've been looking for what native plants grow in the areas hermit crabs are found. I've found several interesting things just today on that:

# 1
I already know that hermit's LOVE mangrove and it's become clear to me that it is an essential part of their diet since it's found in almost every native environment of land hermit crab (especially E's and PP's). So I need to increase the intake of this because it's almost always available to them in their native environments.

# 2
In native areas there are some plants that only certain animals can eat but anything outside of that species of animal will become poisoned when they munch it. One plant I'm looking into details of what it is would be this:

The article reads, "The case is proven in the Antilles by euphorbiacean trees like the manchineel (Hippomane mancinella) which sweet and fragrant fruits are deadly to humans and most other large mammals, who are likely to swallow the entire fruit and digest even the seeds. But other animals, like Cardiosoma land crabs and Cyclura rock iguanas, eat them with total impunity, after which they discard or defecate the seeds intact. (These animals' flesh might then become toxic to, say, humans who occasionally eat them, in a way similar to how some butterfly caterpillars ingest and incorporate into their own tissues toxins from their larval food plants, thus even as adults becoming unpalatable to birds and lizards)." -Link to Article

This is just a "because I wanna know". That plant may mean nothing to land hermit crabs. I do want to know what a "Cardiosoma" crab is... and how close a land hermit crab is to that species. Plus what is this plant... hehe...

# 3
This is VERY interesting information that I found about coconut crabs and what their diets consist of that leads to whatever color...

The article reads, "On some islands, the crab has altered its diet from coconuts to lau hala (Pandanus tectorius), another fruit whose seeds drift on the ocean currents. Coconut crabs with a main diet of coconuts are blue and lavender. Crabs with a diet of mostly Pandanus are bright orange." -Link to Article

For this I want to know what that plant is that some of them use instead of coconut. Hehe...

So my Conclusion:
From this small amount of information I may try something... Since I've noticed that my E's turn brown... and I don't feed coconut EVERY day... maybe that would be something to increase in their diet. Notable information at least. Maybe coconut, mangrove, fish/shrimp and seaweed need to be offered EVERY meal and rotate the other varieties from there. I may try that.... hmmm...

Okay... must go pack some stuff. Need to sort some things. Moving can be so exhausting. I'll pick this up in another post.

Some articles I wanna read later:
Link 1
Plant Listing to Sort Through
I want to know more about coastal and sea grasses too.