lettuce nudibranch eggs

[cmsargent]

My lettuce nubi laid eggs sometime yesterday (at least I'm pretty sure it was the nudi. There are thousnads of tiny white eggs in a clear rope, laid in a spiral pattern). I'll have to get a pic and post later.

I'm wodering if the eggs are viable. I only have 1 lettuce nudi (I've had him about 3 weeks now). I think I read somewhere that these gals can store sperm and release multiple batches of eggs. Is this true? Do they lay non-fertile eggs if they're no mate around?

If these do hatch any advice on keeping the young alive?

 

[greenbean36191]

It does sound like the slug is the culprit. Slugs (these animals are not nudibranchs) often lay infertile eggs when they're starving. This sounds like what you're seeing. Some slugs can store sperm for short periods, but 3 weeks would be pushing it probably.

If by the off chance these are a fertile batch, they could hatch into crawl away juveniles, lecithotropic larvae, or planktotrophic larvae. The trouble in knowing is that there are at least 3 species of slug sold as lettuce slugs, and probably a few cryptic species within each group. Their reproduction varies between each species. If you get crawl away juveniles then they'll do fine feeding on the same thing as the adults. If you get one of the planktonic larval forms they aren't likely to survive in a typical tank.

 

[cmsargent]

Just curious why these slugs would lay eggs when they're starving? Seems the opposite of what most species do (i.e. only lay when they're healthy as egg production uses quite a bit of energy).

I know these guys starving in tanks can be a problem but I have lots of HA in my tank and this guy does seem to be eating (though it's hard to tell I supose). If infertile egg laying is a sign of starvation...any suggestions on providing a better food source and keeping this guy alive?

 

[greenbean36191]

The animals don't seem to realize that the eggs are infertile, but they know time is wearing thin for them. If they die without making any reproductive effort then their genes get weeded out of the pool and their life was essentially wasted. Instead of letting that happen it seems to be their instinctive reaction to devote their last bit of energy to reproduction rather than trying to prolong their lives a little while longer. Keep in mind these are fairly short lived animals anyway, only living about a year or so. It's not like this strategy dramatically shortens their lifespan.

Usually once they start laying the infertile eggs, it's too late to save them, but you could try a few different foods. Which one it eats will depend on which species of slug you have, but they've been reported to eat Bryopsis, Derbesia, Halimeda, Penicillus, and Caulerpa. If it's eating, it should keep a deep green color.

 

[cmsargent]

Well I guess I'll just wait and see and hope for the best.

This guy is in a planted seahorse tank. It had 4 types of Caulerpa, Halimeda, Penicillus, and patches of Bryopsis. I also have a couple of other types of green algeas, 5-6 red algeas, and a couple of browns. I've also let the back wall of the tank become covered with a patchwork of diatoms and HA (it seems to act as a copepod breeding haven).

He seems to have a nice green color (not pale or washed out). Here's a pic of him.

The only reason I thought I might have a chance with a sea slug is because of the abundace of algea in my tank. This guy seems to spend a bit of time on one of the Caulerpas (the one in the attached pic), the Penicillus (I didn't know they eat Penicillius and was wonding why he spends so much time on top of it), or the back wall.

 

[greenbean36191]

Well, the color of it certainly looks fine. I guess you just wait and see what happens.

 

[kryppy]

I had some eggs hitchhike into my tank. I saw a pair of super tiny ones cruising around for months on end. Eventually they disappeared at about 1/2". I don't know why. Plenty for them to eat.

 

[LeslieH]

This one is Elysia clarki (although the validity of this species is debated by some taxonomists). Here's what was published about it's feeding habits & life span on the The Sea Slug Forum by Bill Rudman:

"E. clarki has lecithotrophic larval development [non-feeding planktonic larvae] with veliger larvae metamorphosing into juvenile slugs after about 5 days. Extensive feeding experiments (Curtis et al. 2004) have found the juveniles will eat Bryopsis plumosa and Derbesia tenuissima [but not Caulerpa verticillata as reported by Jensen (1980)]. The length of the life cycle is unknown, but Pierce's lab have raised E. clarki from eggs in the laboratory that are still alive after 22 months and have not yet reproduced."

You can read more about this species at Rudman, W.B., 2006 (May 30) Elysia clarki Pierce, Curtis, Massey, Bass, Karl & Finney, 2006. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet.cfm?base=elysclar