HCA: Hermit Crab Association

So.....do crabs need light? And if so, what kind of bulb is best? How often should the light be on? Crabs seem to like it best when it is dark, so I wonder if light is even necessary.

it is believed that crabs are nocturnal to proctect against predators. there are certain wavelengths of light that are necessary for nearly all animals. amongst other things, sun light assist the body in absorbing calcium. i have a full spectrum bulb in my tat, and since i started using it i have found my crabs to be more active throughout the night, and even spurts of activity during the day.

isn't there a specific kind of bulb that helps them to absorb calcium? or a specific watt?

i think any light bulb that offers the same wave lengths of light as the sun is good. wattage indicates the amount of power the lightbulb needs . The higher the wattage, the more energey needed the hotter it gets.(i believe i worded that right)

I have a 15 watt reptile light for my crabs. I leave it on during the day and turn it off in the evening. In addition to keeping the temperature in a good range, it helps give the crabs UV rays which they would get in the wild. I've noticed an increase in activity since using the light. The lid on my tank is one of those overhead tank hoods, so the light I use is one of those long strips of lighting, but I'm not sure what the name of it is.

I use a Black light in my Tat it offers a nice darkness in the daytime that even in a lit room still coats everything with a semi twilight glow and at night it offeres just enough light for me to see whats going on without disturbing thier nocturnal ways. It even usually ups my temp 1-2 degrees

My tank came with a hood that has a standard light socket in it. I have a 15 watt compact flourescent in it currently, I read that they give off UVB rays (like the sun). I have the light turned off at night and on during the day. Once I get a moon glow bulb I will use it at night.

ElliEve, do a search on black lights, I read that the light they give off is not natural to what crabs see in their natural habitat.

I use a Repti Bulb 5.0 as my florescent and a 25 watt heat in my other. I went with the 5.0 because it's for tropical climates. 2.0 is an all purpose one and the one between it is for dessert climates which you don't want to use because it's harsh. Night I use a moon glo.

is that repti bulb 5.0 one those long ones? or is that just a regular shaped bulb, or shaped like a flood light? my tank does not have one of those nice lids with the bulb set up built in. So, I think i will be getting a regular shaped bulb of some sort.

I can't really say whether or not crabs like light, but what I've noticed with mine is that when my 15watt nightglow blub died and for three nights there was absolutely no light during the night, there was a drastic decrease in activity I found. Three days later when I got a new bulb, that night I was up practically until 3 because they were litrally trucking around the tank. I would definetly recomend a bulb that sets a twilight zone during the night, because even though they're nocturnal, all animals need some fraction of light to see.

elephantshark44 wrote:is that repti bulb 5.0 one those long ones? or is that just a regular shaped bulb, or shaped like a flood light? my tank does not have one of those nice lids with the bulb set up built in. So, I think i will be getting a regular shaped bulb of some sort.

It's a long light. I use a tri bulb hood. So, it has a space for a long light and two small lights. My long light and one small run all day and the night light goes at night. I use the 5.0 and then a small bulb that is for more UV rays to supplement the ones from the long light.