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I haven't added to the blog lately because I wasn't seeing anything moving in the tank. However! The news is that tonight I can see 1 (one) tiny horseshoe crab moving on the bottom of the tank. One. There used to be lots and lots of them. Now only one. Kind of depressing because it's the same thing that happened last year. What is it about early August and this house that does them in????? I would take a photo but I don't want to risk killing it. I'm going to name her Hermione. It's a bit tough to name 70 but with only one, I don't think I'll run the risk of calling her by the wrong name.

Meanwhile, our contact at the MD Dept of Natural Resources posted a youtube video of what her tank looks like. She's probably got 300 little critters on the bottom of her tank. If I can figure out how to embed that from youtube, I will post it here. The only difference between her tank and mine is that if you took out all but one horseshoe crab, it would look exactly like mine.

Gallows humor.

August 10 - What's up?!

Not seeing a whole lot of movement in the tank. That's been true for the last few days. I fed them again. Yesterday I gave them 2 cubes of the baby brine shrimp and then added in one of the bigger cubes of just plain ol' brine shrimp. Today I put in another big cube. Feed them! That's the ticket!

The main clump of them is in the end near the air stone. I don't know if that's the result of currents in the tank or what but that's where they are. A few are down near the filter so I made sure to get some of the brine shrimp to them as well. It's a pretty long trek for them down to the big clump.

August 6 - So how big are the baby horseshoe crabs? And other questions.

How many do you think would fit on a penny? 12? That's my estimate. Or guess. Anyway, you now see the famous pyrex bowl I've been using to take photos. On the equally famous red table with the white kitchen garbage bag that the aquarium sits on. This is a molt - an empty shell - so the horseshoe crab that came out of it is about 25% bigger than the molt.

Now on to my latest concern. I'm seeing lots of molts in the tank but not a lot of movement. That's probably okay. The videos below are of the accumulation of molts in the tank where some little crabs are moving around. For the second one, I used a tablespoon to gently - sooo gently - scoop out some of the molts/crabs into the bowl. You can see one moving around.

And last are two photos. The first is of some of molts that were floating on top of the water - so none of them are alive.

And then there's the one below. I could only see one of them moving. So - do you see much difference? Are some of them in the photo below alive but not moving? Stay tuned, horseshoe crab fans.

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!