Posts Tagged ‘baby’

The Gift – A Fiddler Crab Extra!! Meet the Babies!

March 2, 2008


Okay. You’re wondering what in God’s name this thing is. Well, it’s one of the crab babies, at least my rough sketch rendition of one. (If  you want to see real photos of the zoeae and later larval stages of fiddler crabs, click here ).

It’s the best I can do. I’m spoiled because I am used to working in labs with good equipment.

In the lab I would have put an aliquot of liquid from the aquarium in a test tube, spun it down in the centrifuge, poured off the supernatant, and made a slide out of the sediment, which would be concentrated crab larvae, instead of chasing one unlucky soul all around the microscope slide trying to catch him long enough to see him.

I would have had nice stains to chose from to make the larvae show up better. Today I had McCormick’s yellow food coloring from Harris Teeter.

I would have had a nice Zeiss microscope with oil immersion lenses and fine optics. Instead, I have a Milben kids’ microscope, circa 1965, in a wooden case, with an EverReady 5 volt flashlight shining in the mirror to light the stage. (And if you want a kick, click here to see a similar setup to my microscope and wooden case. It even has the dissecting kit tool indentations in the styrafoam. I had those dissecting tools a long time ago. It says something when you search Google for Milben microscope and it’s listed under “antique sites.”)

I would have had a nice Zeiss microscope with a camera attached to photograph what I saw. Instead, I had to sketch it. I don’t have one of those neat electronic tablets to draw with. All I had is the “pencil” tool on my son’s Photoshop program that I barely know how to use.

So, I know, stop whining. I’m not in the lab anymore. Given all this, I still managed to catch one crab baby, watch him through my very “SUB-OPTIMAL” microscope, in food coloring stain, and draw you a WAY suboptimal sketch.

But still, what the sketch shows is the head part on the right, with two little “?claws” moving back and forth rapidly. It stretches out with the tail on the left. We could even see “material” moving through the crab from the head, out the tail. Yes, out the tail. My husband caught that one. So I guess we can assume the crab baby has been eating the food I served. 🙂

In any event, minus all the fancy equipment, it’s the best I can give you, but still it’s something. I should note that this was a 100x magnification.

We have noted that Days 1 and 2 there was a fair reduction in numbers of larvae and my husband noted the blackened area that looked like a mass murder in one corner of the tank deep down in the gravel where many babies perished. Still, there are LOTS of babies swimming in the tank AND they are bigger than yesterday. If you hold a magnifying glass up to the tank, you can see tiny tails. So some are thriving after all.

If many many thrive, at least the guys at Fish Pros said they’d be happy to buy some from me for cash or store credit. That would be great. I’m always in need of new supplies. 🙂

Salinity is almost “ocean” at 1.017. Should reach 1.020 later today.

Anyway, now you’ve “sort of” met the babies.

….about that centrifuge – it occurred to me I could take a small, capped plastic tube and tie a rope around it and spin it around my head. Then I thought, maybe even better – tape the tube to the inside of my washing machine and run it on the spin cycle. But leave it to my engineer husband: find a way to attached two capped tubes on a rod opposite each other, connect them to a power drill, and turn the drill on….THAT’S the best RPMs for the money. 🙂

The Post – What to Feed the Babies and How Salty Should the Water Be?

March 1, 2008

Just a reminder that coming up over the next week, the next few installments on the journey of my Under the Pier novel. I had to take a break from those for taxes, actually finishing some more chapter revisions, and of course, taking care of the “grandchildren.” But stay tuned. More to come on Under the Pier.

Re the grandchildren:

What wonderful goings on! Soooo many little black dots in the nursery and they are definitely swimming around. Many are hiding out in the shadows of the live rock caves. So tiny and already they know to hide and avoid “predators.”

I am feeding them three times a day with a mixture of ground up mini-freeze dried krill, some ground up flake food, a few drops of the liquid Small Fry baby fish food, and a little distilled water mixed in. We shall see how it goes. And no, I am not grinding the mini-krill with my husband’s lovely stone mortar and pestle that he uses for grinding up herbs and spices in the kitchen!!

Regarding salinity – it’s a tricky call. While Uca minax, which are the type of fiddler crabs I have, are seen furthest up the estuary in areas of lowest salinity, there seems to be evidence that for at least the first two weeks of their larval development (zoeae) , they actually survive and do better at a higher salinity. However there is also evidence that for the next (megalopae) stage to metamorphose into crab Stage 1, this species does best with the lower salinity seen in the upper estuary environment that the adults live in. I will post more information tomorrow including the links to the two papers I found today on this subject. Long story short today though, is that zoeae of all the species of fiddler crabs, seem to need a couple weeks of “being at sea,” hence higher salinity.

I’ll also explain about the three species used in one of the studies and how their selectivity for salinity levels puts them in different spots in the estuaries and thus probably keeps them from competing with each other for resources and food.

Also to come – I dug out the small microscope I had as a kid and will pick up some microscope slides. So to follow, descriptions of babies, under the glass.

A couple of other notes – courtesy again of my engineer husband. He noted a bunch of white things all over the gravel and wondered if the babies had already molted. Maybe they have but these white dots were too big and irregular in size for baby shells. I believe it’s salt crystals that didn’t dissolve in the water before I added it. I added more water to bring the salinity up closer to a marine environment. I started at 1.010 (brackish) when they were born and over the course of yesterday raised the salinity first to 1.012, then by last night 1.015. Today I’ll finish raising it to 1.020. Then in two weeks I’ll bring it back down to 1.010-1.012, the optimal range for Uca minax adults.

Sand. Again, my husband was watching the babies swim – it is amazing to see these tiny things whiz around the tank – but he shined a light to see if they would follow the beam. The article I posted in yesterday’s gift mentioned that the babies will go to the light. My husband didn’t see evidence of that, but what he noted was that many little babies had worked their way down between the gravel bits, all the way down to the bottom of the tank. Unless they figure out how to get back up to the water, they’ve had it. Now let’s face it. Their parents had a brain the size of a pinpoint. How large a brain do you thing babies the size of a pinpoint have? So the odds of them getting back to the surface are not good. I said “evolution at work. Anybody who tunnels down in the gravel probably won’t live to reproduce. ” My husband noted that gravel is less than optimal for this (engineers talk like this by the way, things are optimal, less than optimal, sub-optimal 🙂 ).

The real important point though was his next comment: “The NEXT time we do this, we should use sand.” There you have it folks. My husband has fallen in love with the fiddler crabs. In all truth, he has. He watches them, thinks about how to make their lives better, anticipates the babies getting ground up in the water filter…..those babies are lucky to have him!!!

Anyway, stay tuned for the links on those two articles about optimal (yes, OPTIMAL) salinity levels for fiddler crab larvae.