Question about red color of Halocaridina rubra (opae ula)

ernopena · Post by **ernopena** » Mon Jun 26, 2006 12:46 am

I was trying to find the answer to this question online. Maybe someone here can help...

Does the intensity of red color in Halocaridina rubra (Hawaiian Red Shrimp, Opae Ula) indicate health?

The reason is that I came upon these photos from Scott Santos's research website. Then later I read somewhere in a research paper PDF that shrimp found in nutrient rich anchialine pools with ample food sources displayed the same characteristic, dark colored thorax with a dark line in the abdomen indicating a full intestine. You can see this in Photo A.

This then begs the question, why are these "happy, healthy, well-fed wild" shrimp not bright red like the shrimp in the pet-store fish tank in Photo B?

My shrimp are nowhere near this bright red. Does the bright read color come from a certain diet, a certain algae? Or maybe from large numbers in close proximity?

Is anyone elses opae ula normally this bright red all the time?

Any insight would be helpful... Thanks.

Link to Scott Santos' Lab website:
http://gump.auburn.edu/srsantos/gallery ... _itemId=46

Here is Photo A:

Here is Photo B:

Photos by Scott Santos.

YuccaPatrol · Post by **YuccaPatrol** » Mon Jun 26, 2006 4:06 am

I was fortunate to attend one of Dr. Santos' lectures on these shrimp this spring. I also consulted with him by email for assistance with a research paper on these shrimp.

I summarized some of the interesting points in the lecture in this thread:

viewtopic.php?t=1445&highlight=

I do recall that he mentioned that there is variability in the coloration of the shrimp in the wild.

His most current paper focuses on studying the genetic differences of these shrimp in different location on different islands of Hawaii. Surprisingly, the genetic differences found are very significant and may even suggest a future division into multiple species based on his findings.

Coloration of the shrimp is due to genetic variation but there are also environmental factors. As you stated, the dark line that indicates a full intestine would help to make the shrimp appear darker.

In the first photo, you can see that the shrimp are variable in color when photographed close up. The second photo may show seemingly darker colored shrimp but could be a result of lighting, lower magnification, and the incredible density of shrimp in the photo.

In short, if your shrimp are happy and eating, they are probably healthy even if they are not the darkest red shrimp to be found.

badflash · Post by **badflash** » Thu Jun 29, 2006 3:37 pm

My Opae ula seem to be doing fine. I have a lot of BGA in the tank. I can't tell if they are eating it or not. Should I try to remove it? What sort of algae is it that they like?

YuccaPatrol · Post by **YuccaPatrol** » Thu Jun 29, 2006 7:11 pm

You can remove BGA from most any tank with a simple 4 day blackout. No peeking! It's the only effective method I know of that is safe for all other living critters.

Many other types of algae will survive but BGA can't live long without a little sunlight.

The shrimp will be fine for 3 days without any additional food.

badflash · Post by **badflash** » Fri Jun 30, 2006 1:36 am

I'm not worried about how to remove the BGA, I'm just wondering if the shrimp will want to eat it, or if some other algae is what they want.

YuccaPatrol · Post by **YuccaPatrol** » Fri Jun 30, 2006 5:14 am

Few things will eat cyanobacteria. I had a tiny bit of it in my shrimp tank once and none of them were remotely interested.

Post by **Mustafa** » Fri Jun 30, 2006 6:09 pm

The H. rubra don't like cyanobacteria in my opinion. Just remove it by hand and allow *real* algae to take its place. It takes a while to completely get rid of the cyanobacteria when removing it by hand (as it keeps coming back for a while), but at some point it will be gone. I don't recommend the "dark method" as the cyanobacteria don't simply disappear but become part of the organic load after dying.

badflash · Post by **badflash** » Sat Jul 01, 2006 4:31 am

That is what I figured. It is a 5 gallon tank. and not complicated, so mechanical removal is easy. My shimp don't seem to like it either.

TKD · Post by **TKD** » Sat Jul 01, 2006 5:35 am

Is it me or am I the only one seeing green and yellow and mixed colored H. rubra in the first pic?

TKD

badflash · Post by **badflash** » Sat Jul 01, 2006 5:45 am

Read over the beginning of the thread again. I think that is the reason for it to begin with. My shrimp also have wide variations in color, from colorless to greenish to bright red.

Part of it may be the lighting. In lights richer in blues they may appear more green. In lights richer in reds they would appear more red. There is a gem called alexandrite that does this, as well as many other color change materials that change colors depending on incansescent, sunlight FL light.

Neonshrimp · Post by **Neonshrimp** » Sat Jul 01, 2006 8:56 am

Do factors such as food, mood and sex also play in these shrimps' color as they do in RCS?

Thanks.

Post by **Mustafa** » Sun Jul 02, 2006 8:55 pm

Neonshrimp wrote:Do factors such as food, mood and sex also play in these shrimps' color as they do in RCS?

Thanks.

Short answer: Yes.

Add age to that list, too. Younger shrimp are much less colorful.