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imi_sky
2nd Sep 2005, 12:16 PM
hey everyone,

i think this is a simple question, but i am not sure. so here it goes

when a shrimp has eggs, when does it get fertilized, is it before the eggs show up?? or while the female shrimp is carrying the eggs??

retardo
2nd Sep 2005, 04:00 PM
Eggs are fertilized right before the eggs are moved from the "neck" region to the "abdomen." You will see all the males go crazy and swarm the female that is ready to lay her eggs. You may see the male and female embrace with the male on the back/top of the female; fertilization occurs during this embrace.

GunmetalBlue
4th Sep 2005, 03:40 AM
Hi Im_isky, I've learned since posting a Red Cherry thread that the actual fertilization takes place belly to belly.

http://img.photobucket.com/albums/v321/ZeroCatgravity/Shrimp%20-%20RCS/12DSCN0189600WC.jpg

I think the reason the "on top of the back" pose is seen most is because the male alights atop the female and grasps her head and tries to flip her over. I've seen this done while the female is busy trying to eat (ah, the ever opportunistic male! lol ), and if it's not the right time, she will shake him off. I should also comment that the "right time" is after the female molts. But she still is the one who choses to accept the advance or not. Of course if there is a mob of males, perhaps she can't really choose. I've only had one male, so I've not observed mob behavior.

Of course there is always the possibility that if it's a matter of the shrimp delivering a sperm packet with a limb (this part, I don't know), it *could possibly be accomplished in some other position than the belly to belly, but I have been told by a reliable source that belly to belly is the actual mating.

One other comment is that after the mating takes place, I've observed the female - hard to describe - does a quick whip/shake of herself, sort of like what you would do if you were trying to make ketchup come out of an upside-down bottle. That seems to kick-start the process of the eggs descending into the pleopod area, and I've pondered if it is at that time that the eggs pass over the sperm and are fertilized.

I've also observed a female not accept the advance and wait until the next molt (she continues to keep the eggs in the saddle area). Next round (molt), when she feels she is ready, she may choose to accept the advances of a male and fertilization. I've actually been quite impressed with the Red Cherry shrimp's motherhood capabilities.

-GB

amber2461
4th Sep 2005, 01:48 PM
As usual, wonderful photography going on here girl ... thanks for sharing the pictures and your observations too :D

retardo
4th Sep 2005, 02:22 PM
GB--

Can you clarify whether the method of fertilization you described applies to all species of shrimp or Red Cherries only? It is not clear in your response, since you have posted a pic of RC mating behavior. Thanks.

imi_sky
4th Sep 2005, 02:55 PM
hey GB is the method true for all shrimps?? im also wondering about that too

NanoDave
5th Sep 2005, 12:52 AM
From the look on the shrimps' faces I think he took the photo at the just the right moment... lol :D

GunmetalBlue
5th Sep 2005, 05:06 AM
Oopz! Yes, thanks for asking - my observations concern Red Cherries only. I don't own many of the other shrimps, so haven't been fortunate enough to observe their methods.

Haha! My shrimps don't get much privacy, do they? lol

-GB

Walter
14th Sep 2005, 04:51 PM
I think it is the same method for all crustesean of this type, lobsters mate that way as well. As long as the female carries eggs in the neck region and leg when fertilized, it is probably done this way. :)

Jane of Upton
4th Mar 2006, 06:05 AM
Great thread!

GB - I have a further question (hard to belive after your thorough description, but I do!).

If the female's eggs have already decended from the ovaries (saddle) to the abdomen underside (pleopod area), does that mean she has already mated?

What exactly is the sequence of events?

Is it

1. Molt
2. Mate
3. Eggs Decend

or it it

1. Mate
2. Molt
3. Eggs Decend

or could it be

1. Molt
2. Eggs Decend
3. Mate

Sorry, I'm confused. I'm also excited because my female Snowball shrimp (very similar to Red Cherries) was carrying eggs in her pleopods this morning, and seemed to be in the vicinity of a fresh molt skin that was likely hers. I have three males in the small tank (5.5 gal planted) and one (the biggest one) was occasionally coming up to her, and they seemed to batt at each other with their legs, then he'd swim away.

Is she refusing to mate, or has she already and he's just still smelling whatever pheromones signal that she's receptive/fertile?

And what about when folks see females (Red Cherry) that drop eggs, and other posters say they were probably unfertilized, if water parameters are not to blame?

I'm getting FAR too wound up in my shrimps' lovelife, LOL!
-Jane

GunmetalBlue
4th Mar 2006, 01:17 PM
Hi Jane, congrats on your pregnant Snowball shrimp! :)


GB - I have a further question (hard to belive after your thorough description, but I do!).

If the female's eggs have already decended from the ovaries (saddle) to the abdomen underside (pleopod area), does that mean she has already mated?

Yes (provided there's a male in there).


What exactly is the sequence of events?

Is it

1. Molt
2. Mate
3. Eggs Decend

This is the right one :D . After a female shrimp molts, she becomes available for mating. After mating, from what I gather, the eggs "pass" over the sperm as they descend from the ovaries onto the pleopods (I'm not absolutely sure when the exact moment of fertilization is). At any rate, the eggs are definitely fertilized (or not, as the case may be) by the time they are on the swimmerettes (pleopods).


Is she refusing to mate, or has she already and he's just still smelling whatever pheromones signal that she's receptive/fertile?

As to the males still chasing the female around after the eggs are already on the swimmerettes, they probably are just responding to the pheromones, but the initial mating to fertilize the eggs most likely already took place. I've seen females try to escape the situation and hide out if she continues to get harrassed.


And what about when folks see females (Red Cherry) that drop eggs, and other posters say they were probably unfertilized, if water parameters are not to blame?

An update on my most recent experiences with female cherries is that after a molt and WITHOUT the presence of a male RCS, the unfertilized eggs can and will descend onto the swimmerettes. Those are the eggs that will be "dropped." Sometimes the eggs drop right away, that's why someone might say the saddle "disappeared" but they never saw the eggs. That's because it dropped when the owner wasn't around or did not notice. I've also had a female "hold" her unfertilized eggs on her pleopods for as long as 4 days, then finally, the last egg dropped.

So, if I'm ever wondering if eggs on swimmerettes are fertilized, I give it 4+ days to a week; then I know for sure they probably are fertilized.


I'm getting FAR too wound up in my shrimps' lovelife, LOL!

It's all good - to have curiosity helps us observe and learn! lol

-GB

Jane of Upton
4th Mar 2006, 08:04 PM
Thank you SO much, GB! A thorough and thoughtful answer as always! I really appreciate it!

So, with 3 males present, I can be pretty sure she's mated. Here I was thinking I might have a "frigid Snowball", LOL!

Well, now I'll be watching for the next several days, to see if she holds them. The eggs are not as pristine white as I've seen in pictures, more of an antique white. But, for heaven's sake - I'm sure I'm just worrying about every little thing! It HAS been very interesting to watch her, and with the color of the eggs, and the clear exoskelaton, I've been able to observe more of what's going on than I can with Red Cherry eggs in the pleopod area.

Your photography is wonderful, by the way! That closeup on the shrimp "in the act" is fabulous!

Thanks!
-Jane

Jane of Upton
5th Mar 2006, 10:03 AM
Oh well, congratulations were premature.

I found the whole clump of eggs hanging on some plants this afternoon. Also, the other female had molted overnight, and was hiding up under a crevice where I couldn't see her. Then, a few hours later, her eggs dropped out (still couldn't see her, but saw the eggs rain down).

Oh well.

Both female shrimp look fine, and are both eating well, so I'll be patient. It occured to me, perhaps the males are not fully mature yet - that could be a real possibility.

One interesting side note - the area around the pleopods seems to have more depth on both females now. I wonder how common it is for the first brood to just be practice? I used to see no difference between the body shape of the males and females, but now, even without the ovary saddle showing (which used to be the only indicator of gender) I can spot which is a female, and which is a male within a moment of glancing at them. I wonder if the females' bodies needed to develop this expanded pleopod area in order to hold the next brood?

LOL - I guess they've lost their "girlish figures", eh?
-Jane

Beviking
7th Mar 2006, 03:23 AM
It is my understanding that the sperm are delivered and held in a gelatinous "packet" (produced by the female). So when GB says "...the eggs 'pass' over the sperm..." that is what is happening.

Superb photography as usual GB!!!

Jane, I don't know for sure but in many fish species, the males become sexually mature before the females. That would be an interesting bit of information to know. So to would be your postulations on "practice run pregnancies" :)
Sorry to hear your eggs dropped :(

-Be

retardo
7th Mar 2006, 05:09 AM
One interesting side note - the area around the pleopods seems to have more depth on both females now. I wonder how common it is for the first brood to just be practice? I used to see no difference between the body shape of the males and females, but now, even without the ovary saddle showing (which used to be the only indicator of gender) I can spot which is a female, and which is a male within a moment of glancing at them. I wonder if the females' bodies needed to develop this expanded pleopod area in order to hold the next brood?

LOL - I guess they've lost their "girlish figures", eh?
-Jane

Yep. Once you get acquainted with the differences, it's almost a cinch to figure out without hurting your noggin. lol

Certainly the pleopod area will grow as the female matures. More mature females will have more eggs than a juvenile female. Eggs have been known to hang outside the pleopods because the pleopod incubation area is not large enough.

Also, be aware that Cherries and Snowball shrimp are from the same family and can cross-breed, so if you have both in the same tank, isolation may be a good course of action.

Nickel
8th Mar 2006, 08:03 AM
Can I ask if the eggs hatch while on the female's swimmerettes or eggs are released onto sand bed before their hatch ?

REason I ask is that I intent to change the current substrate to ADA Soil and if eggs are released on sand before hatching, then I will think of alternative method to change the sand to ADA to control PH.

thanks.

retardo
8th Mar 2006, 08:47 AM
Eggs are released from the swimmerettes. During the hatch, the female is constantly fanning her swimmerettes. One by one, the new batch shrimp launch from the swimmerettes into the water. The fanning motion is part of the birthing process.

Nickel
8th Mar 2006, 09:31 AM
Thanks for fast response, retardo.

I believe once hatched, the new fry should be at least mobile enough to get out of way when I replace the sand with ADA. Of course care needed to go slow (over period of few days) to prevent de-stablise the water parameter too sudden and huge swings.

Great help. Cheers.

Obama
21st Jul 2008, 02:12 PM
two related breeding questions on cherries ;

1. do the females tend to get pregnant around the same time ie mating seasonally or in response to some kind of stimuli or environmental trigger? Noticed that i have quite a few pregnant females lately; something that wasn't there a week or so ago.

2. I have seen pregnant females with white, yellow and even greenish-black eggs. Are these different stages of egg development or are some of the eggs unfertilized or gone bad?

crandf
22nd Jul 2008, 02:22 PM
Am I the only one disturbed by the presence of this picture of animal porn?