Petshrimp.com Discussion Forum

Way to go! Your hard work is paying off. I hope this is the first of many more to come. Thanks for the nice picture of the little one

Newjohn wrote:What was the time frame, from when you noticed the berried Female to the dropping of the babies ?

I'm afraid I don't know yet, as I noticed this female when she was already carrying hatched eggs. But now that I have isolated the last batch of berried females, that I have been talking about, I'll be able to figure out the answer to this one soon.

Thanks everyone, but the real credit goes to the crayfish and all I do is give them some clean acidic water and some food from time to time. I'm just fortunate enough to be able to observe them doing what they do.

Congrats and nice pic. You are doing a great job. Keep up the good work.

Jason

Now there are 5 baby crays from that one female. It took an extra 2 days for the last one to drop off.

I think it is a very good thing to be isolating the berried females, but when I moved a female from one isolation tank to another, she lost several eggs in the process. From here on out, I am going to do my very best not to disturb pregnant females once I have them isolated.

Even though they start with a significant number of eggs, these crays are so small that it seems that only a very few eggs make it all the way through larval development.

Would it be possible to hatch the dropped eggs in an egg tumbler, like the ones used for cichlid eggs when the females are stripped?

I don't know if such a thing would be possible. The problem I see is the fact that the larvae do receive some parental care between hatching and molting into a free-living juvenile. I just don't know if they would they be able to undergo all of their larval stages without the parent.

Last night, I pondered why these crays would produce 20-30 eggs but drop so many of them because what I am observing in my aquaria is typical of what has been reported from wild collections. I formed this rough hypothesis:

These crays evolved from larger species, and there must have been some competitive benefit to being small for them to make this evolutionary step. I suspect that this benefit is their ability to utilize their very specific habitat of emergent vegetation in shallow water along the banks of streams.

Although the body size has decreased, larval development still requires a normal sized egg. Also, there is very limited space available for juvenile crays to develop underneath the adult female.

So, in short, their reproduction is very limited due to the relative large size of egg compared with the body size of the female. Even though they are capable of producing a relatively large number of eggs, their body size is too small to be able to carry all of them for the duration of larval development.

To put their size into perspective, C. diminutus grows to half the length of C. shufeldtii. This means that the actual body size is 1/8 that of the larger species. Because of this, I expect that the maximum number of offspring per female will not ever exceed 10.

Very interesting! Since they develope from normal sized eggs, their babies must hatch at a size comparable to larger speies. Does this shorten the time it takes to for them to reach adulthood compared to the larger sized species?

Another advantage to the smaller size would be food/energy requirements. Smaller species require less than larger ones, so a larger population would be sustainable on limited resources, territory space, etc.

ToddnBecka wrote:Another advantage to the smaller size would be food/energy requirements. Smaller species require less than larger ones, so a larger population would be sustainable on limited resources, territory space, etc.

Definitely! There are always so many factors that influence the appearance and behavior of species.

The sand bottomed streams they live in have very few rocks so there is minimal cover available other than plants. A small crayfish can blend into the plants and leaf litter much easier and avoid predation.

Just a photo from this evening of a newly isolated berried female. This is a good example of the maximum number of eggs I've seen.

Interesting. For comparison a C. shufeldtii:



I know the C. diminutus female is smaller so the eggs look larger on the C. diminutus female, but I wonder if the eggs are still bigger than the C. shufeldtii eggs. Those eggs look huge!

Other than keeping the eggs/larva oxygenated, what other care would the female provide? It seems unlikely she would feed the larva.

With the assumption that Mustafa's crayfish is twice as long as mine, the eggs appear to be approximately the same size. At some point in the future I will measure eggs size, but for now I'll just say they are "about the same size". They are definitely huge in comparison with the tiny body.

After hatching, there are still two larval stages that must be completed before the free-living juvenile leaves the mother. The larvae are still feeding upon egg yolk during these stages, but it may not be possible for larvae to develop through these stages without being attached to the female. Hormones from the female may play a role in larval development.

In addition to oxygenating the eggs, the females also clean the eggs to prevent fungal or other infections.

The female above was about 1 1/4 inches or a little over 3 cm at that time. So, your female is only about 1.5 cm? That would be truly tiny and explain why the eggs look so huge.

I'd try incubating some dropped eggs in a fine-mesh net breeder with an airstone to circulate water, either in or under the net. It may not work, but would be quite worthwhile if it did. Even if only a few develop, it would still produce more crayfish to work with.

I know nothing about what role hormones or other care provided by the female may play in the development of the larva. It just seems possible that they may develop the same way fish eggs do if artificially incubated.

What becomes of the dropped eggs? Are they eaten?