July 27 - What's that cloudy stuff on the bottom?

Here's a photo of the bottom of the tank. I was at the side of the tank taking the photo

And this is a larger view of part of the top photo. What do you think the cloudy stuff is?

I think it's the molts. I think they pile up in part of the aquarium because of water currents caused by the air stone and the water filter. Just my guess. I think last year I was so fungal-phobic that I thought the cloudy stuff was fungus and took it out. It's true what they say - second time moms are more calm than first timers.  

Checked the chemicals today and all's well. The salinity is up to 14 ppt and the other levels (pH, nitrates, nitrites, and ammonia) look about the same. That's good. 

I'm feeding them 2 of the frozen baby brine shrimp cubes every other day. I think they're happily eating it because I'm not seeing any obvious accumulations. 

July 24 - Another molt?

You know, I think they've molted again. I was away for a couple of days, my husband saved the day when the power went out (again!) and he replaced the batteries in the battery operated air pump. I hadn't looked at the little fellows since before I left but it looked like there were more molts in the tank. So tonight I took some photos - again in the glass bowl on the red table. Now you can actually see tails! Maybe they've made it to that point in their development where they look completely like horseshoe crabs and less like tail-less trilobites!

There they are. Some are molts but the ones with the eyes are definitely horseshoe crabs. They seem to be thriving. When I turn on the light, they seem to get more active - you can see more in the tank.

And, of course, I took a very quick movie with my iPhone:

I wish I had a better way to take videos, especially close-ups. Maybe I'll figure it out. Anyway, that's it for today. I am definitely see a lot more activity than last year. I think this tank could have 60 - 70 horseshoe crabs. Wow!

July 19 - Swimming in slo-mo and body parts

http://www.youtube.com/watch?v=sCtAv7fU1lc

I love this youtube video! It's a terrific look at the coordination required for horseshoe crabs to swim. They are really beautiful swimmers and they use their book gills and all 10 legs flapping together. It's pretty amazing. This should work when you click on the button but right now it doesn't seem to. I'll work on that.

Another one of my videos of horseshoe crabs swimming in a white spoon. I'm trying to figure out what stage these little fellows are at. Obviously not eggs, so they're some stage of larval development. Eventually, they will have their long tails but not yet. I thought they had the start of their tails (telsons) but I'm not so sure. So I've done some research. To understand this, you'll need to know something about horseshoe crab segments or body parts.

Horseshoe crabs are divided into three parts: the prosoma which is the big round part, the telson or tail, and the opisthosoma which is between the telson and the prosoma and has the book gills and the spikes on the outside of the body.

Here's a photo I took today of a larva (again in the white spoon):  

Here's a google image (not my photograph but they look pretty similar:

http://www.city.kobe.lg.jp/information/public/online/photo/number18/english/small_features/index3.html

The site of the google picture describes this as a "first instar larvae." That's a pretty fine name! So I'm going to conclude that whatever the name, there's not yet a larvae with a telson. Prosoma, yes, and opisthosoma, yes - but no telson yet.

And that's the end of this lesson! 

July 15 - 1st molts after hatching

How colorful is this photo? It's all thanks to the molts being in a glass bowl on a red table. But aside from the color, the interesting part is that these are the first molts after the larvae hatched from the eggs. There's no tail - the upper center one shows that best, perhaps.

This one shows the underside of a molt. This doesn't look exactly like a horseshoe crab yet - no tail! - but it's one of the early stages.

And finally for today - a picture of the corner of the aquarium where most of the babies hang out. The blue glob is actually the aerator stone - it looks fuzzy because of the air bubbles coming out of it. This is not a high quality photo but I'm guessing this shows about 50 and another 20 are in the rest of the aquarium. They get active when I add the baby brine shrimp - hungry little fellows!

July 13 - Testing!

Today was chore day: doing all the chemical testing, recording the salinity and temperature, and upping the salinity a bit since the little darlings need to be up to about 20 ppt by the end of the summer. They have been very active lately - much more crawling around on the bottom as the video shows. I estimate that we have about 50 little crabs right now. When I was pouring water into the tank to increase the salinity, I noticed a lot of molts or sheds floating around in the water. I cleaned the filter but they didn't seem to be in the filter so the molts/sheds must be on the bottom on the sand.

Here are the results from the chemistry tests today:
Amonia is the test tube at the left (light green) = 0 (good)
Nitrites are the middle test tube (blue) = 0 (good)
Nitrates are on the right (yellow) = 0
The nitrates are down from 10 and I had added some biospira.

This is the pH, which is about 8.0 and that's good too.
I only have 3 test tubes these days because one broke last year.

The temperature is about 79 degrees which isn't great but it's been consistent and they seem to be thriving so that's okay too I reckon.

(2 hours: testing, preparing water, writing it all up)

July 10 - Part 2

So, I thought it might be fun to do a little video of what the crabs and the tank are looking like now so here goes...

Today I could see 2 different forms of horseshoe crabs larvae - the young ones still don't have tails and swim a lot in the morning. The second type form looks almost like the sand. Pretty good camouflage. The first video shows the two different ages in the same spoon. I say in the video that the larger ones might be ready to molt - but maybe what has happened is that they've already molted and their shells aren't completely hardened yet because you can still see through the shell. I'm just guessing here. Or maybe their digestive system (guts) aren't fully formed yet and that's why they're semi-transparent.

The second video you'll have to look at pretty carefully to see any movement in the sand - like I said, they are well camouflaged and active.

And now for the latest photo: this larvae looks different from the earlier one - the formation of a little tail (maybe) and the lack of a pinkish attached yolk. It's a faint photo and I tried to improve the contrast but it's not the greatest.

It looks a bit more formed than the other day - you can kind of see the tail forming? Maybe? I'm thinking there's no yolk meaning that it has gotten to the point of needing food so I'm glad I added brine shrimp today. This one was on his/her back so you can't see the eyes. 

And that's what the tank and the crabs look like now - July 10, 2012

July 10 - Update

I checked the chemicals in the tank yesterday. Everything looked pretty normal but for the first time - including last summer - I got reading of 10 for nitrates. Yikes! Everything else was fine. I checked the instructing book that said with nitrates, a reading of 100 would be reason for alarm. But I added some more biospira just in case. Probably didn't need to - but just in case. It was about a quarter of a bottle.

Also, today I added a cube of baby brine shrimp. Just in case. I think they're still mostly feeding off the yolk but maybe some of them are advanced enough to be eating food.

July 6 - AMAZING larvae photos

So, this Nervous Nellie (uh, that would be me) looked in the tank today and saw a bunch of larvae floating on the surface and thought - omg! They're all dead!!! Get a grip, Ms. M. I took a spoonful out, took some photos and they started swimming around. OK. So they were just lolling around on the surface. No big deal. I also was worried about the sticks on the bottom thinking they were some kind of organism just waiting to burst forth into nasty little horseshoe crab eating monsters. I took some of them out and guess what? They were just little sticks. Woody things.

But the really awesome part of this post are the following 2 photos.

This is a photo of one larvae showing the eyes
(the 3 black spots) and the guts of the larvae (green). 

These 2 still images are from 2 digital photos I took on my Nikon D50. They are both a small piece of those pictures. Using iPhoto, I cropped them, then zoomed in on the image, and took a screen shot. Voila! Both of them show the yolk sac around the larvae - it's a bit pinkish. That's the source of the larvaes' nutrition after they have hatched.

You can also see the eyes in the top 2 larvae. The bottom
one gives an amazing view of the underside of the larvae

July 4 - Just keep swimming, swimming, swimming

Well, that's a HUGE relief. When we left for the weekend on Friday, it looked like things were starting to happen with the eggs hatching. We left the AC on given the high temperatures outside so I didn't feel too bad about heading out. Then came the huge storm that knocked out power and with outside temperatures soaring to 100+. I have no idea what the water temps were in the tank. When we came back on Monday, the power had been back on so the house was cool and the water temp was around 79. Nothing was happening in the tank. Oh no! There were fewer eggs so I knew a lot had hatched but there were no swimming larvae. Yesterday I saw a few but today - Happy Fourth of July! - lots were swimming around! Life is good in the tank!

Here's what those little swimmers look like (thank you google images for having such great photos of horseshoe crab larvae!).

July 2 - back home after the derecho (no good, very bad, horrible storm)

The nasty storm that struck Friday night left our house without power for 48 hours. The temperatures outside were at least in the upper 90s if not 100 on Saturday. I don't know what the water temperature got up to in the tank. It's about 79 now.

When I left on Friday (June 29), I was starting to see a few hatchlings swimming around. When I checked the tank today I don't see anything swimming and I don't see many eggs. So - did they hatch and die? Are they hiding in the sand? I'll keep looking.