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mogurnda

Solar Sea Slugs: my new project

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Fascinating.

 

I liken your description of #1 to our fat cells.

 

#2 brings up the question, do these slugs have discernible fat cells? If so, #1 would seem to make less sense unless there was some reason to favor two separate strategies for energy storage.

 

#3 sounds interesting.

 

#5 - I like your test approach. 

 

If the chloroplasts were being retained to produce energy and they required energy to harvest and maintain, what would happen if they were plunged into prolonged darkeness? Would they expel (or consume) the chloroplasts since they become an energy sink? Would the chloroplasts simply die?

More great questions, Tom.  I honestly have no idea how they store energy.  Unlike mammals and insects, there is not an obvious fatty tissue, but I expect that there are fat cells somewhere.  They also store sugar as glycogen.  On the other hand, energy storage may be a whole body kind of thing.  They tend to grow fast when food is plentiful, and shrink down to nothing when they starve.  Another area I need to know more.

 

As far as the effects of darkness, starved slugs in the dark do not lose color or the ability to photosynthesize any faster than controls kept in the light.  The idea seems to be that both groups are digesting the chloroplasts once they are starved.  I do not know of any studies in which they were allowed to feed while in the dark.

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Has it really been two years since I last updated this thread?  

 

Lots and lots and lots has happened in the meantime.  The colony is increasingly successful, and we are gearing up for another semester of experiments in the spring.

 

One of the biggest changes in the replacement of the old, narrow slug system, with one that provides better access to everything.  

 

6372_SlugSystem122018-1024x683.jpg

 

The top two tanks are a 20L for Bryopsis pennata, and a 15 regular for sea slug stock; the middle row has half-height 5's and 10's for Bryopsis plumosa, and the bottom has the sump,  Apex controller, and a doser for NO3, PO4, HCO3, Ca, vinegar, and micronutrients.  

 

The biggest breakthroughs have been:

1) figuring out the conditions for sustainably rearing enough Bryopsis to keep the slugs fed.

2) finding out that the babies will only eat B. plumosa, and not B. pennata.  They look very similar, but plumosa is finer.  

 

They start out very cute...

0116clarki011918brood021318adj-1024x683.

 

Soon they have rhinophores and parapodia...

 

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and before you know it, they are all grown up (the girl below is about 2 months old).

004clarki092918-1024x768.jpg

 

I am still fine-tuning the rearing procedures to be a little more predictable, but I am on the third generation.  I just collected an egg mass from which I hope to rear the exact right number of little slugs for the students' experiments.  They are susceptible to starvation and attack by protists during their first weeks of life, but at any other stage the eggs and baby slugs are essentially bulletproof.  

 

It will be exciting to do some neuroanatomy.  Big thanks to WAMAS, by the way, for providing funds for some of the reagents we have been using.  I hope to be able to show off some of the results before summer.

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