Things are moving along, but nothing horribly exciting. Veligers are hatching and sluglets are settling. The brood from 10/30/14 has been rather successful, with a lot of baby slugs climbing out of their shells. I will feel better when I see rhinophores sticking out of their heads and chloroplasts in their bellies, hiopefully by the weekend. Meantime, here is one of the cohort climbing on a Bryopsis branch.
Not much else to say, really.
They may be getting a little more color. I only see one or two at a time. Not sure if it’s a survival issue, or they are just deep in the Bryopsis jungle most of the time.
What is the only thing smaller and cuter than a dwarf seahorse? A baby dwarf seahorse! One of the males has been looking rather pregnant of late, and yesterday was the due date.
The babies are extremely small and pale, and for some reason the camera does not like to focus on them.
It’s hard not to think the adults look proud, even though they are really pretty indifferent to the little guys and the male below is probably not the father of this brood.
The male below is likely to be the father, and seems to have a few more in the pouch.
Because the age of the eggs collected in the previous post is known with some precision, it was a good opportunity to document the time course of development. On day one, the embryos looked like balls of stuff, and did not move much. Below is a video of the eggs, but it may as well be a still.
However, within 5 days, things have really started to get moving. The embryos are starting to look like little veligers, and are spinning in their eggshells constantly. They still have at least 10 days before they hatch, so it seems like a bit of a waste of energy, but it may serve some purpose.
Almost always, egg masses appear sometime after I leave at night and before I return the next morning. I was lucky with this batch, because Mom seemed to be doing something on one of their favorite egg-deposition plants.
You should be able to see the egg mass underneath her as it is being deposited. The eggs to the right are the remains of an earlier mass that should be close to hatching.
Next morning, there it was in all its glory.
It’s a good one to collect for timing of development. So, here’s what they look like on day 1. Balls of cells and yolk, as far as I can tell.
Things are moving along. More veligers have metamorphosed into sluglets, and they appear to be feeding and growing. Come back soon for photos.
I squeezed in a little time to upgrade the setup over the past week. Improvement 1 is the 10 gallon dedicated Bryopsis growout tank on the lower level. The new Evergrow S2 LED lights are supposed to have the optimal spectrum for macroalgae growth (hence the reddishness of the light).
Improvement 2 is the replacement of the ancient compact fluorescent fixture on the Box of Slugs with an Evergrow d2040. Nice little unit, with controls for the blue and white channels. Made a quick and dirty frame from angle aluminum to raise it up to light more of the tank. Still could use a bit more spread.
Next steps include a more controlled environment for hatching and a system for larval growout. As always, stay tuned.
I know you are still eagerly awaiting photos and videos of the developing embryos, but this is just too cool not to post immediately. The eggs I collected October 25 (laid the 18th or 19th) started hatching this weekend. I always thought veligers hovered about in a stately manner, but they really zoom around like radio-controlled helicopters. The video below is pretty awful, but gives a sense of how they move.
Even more exciting is that some of them have settled,like this little one, who still has her shell.
Veliger crawling on Bryopsis.
It gets even better. A few have shed their shells and started to crawl around.
There has certainly been a lot of mortality, and I am trying to figure out how to keep a large proportion of the veligers from getting stuck at the surface. I have also learned that some of the predatory flatworms infesting the Bryopsis are very fast and eat veligers like candy. Little by little, we are figuring things out.
As we start to figure out how to propagate these guys, I thought I’d share a little of the life cycle.
First, when two slugs love each other very much, they become very close. Because they are hermaphrodites, anyone they meet is a possible partner. Since fattening up on Bryopsis, they have been in the mood for love rather frequently. Yes, there really are two slugs in this photo.
The next morning, there was a nice egg mass. In fact, there were two, one on each side of the plant.
Since I knew within about 12 hours when the mass was laid, it seemed like a good idea to collect it and get a better sense of how long the eggs take to develop on the bookshelf. Time permitting, I have been taking photos of the embryos during their development, and they should appear shortly.
In response to hounding from some of my students, I have been trying to move the science portion of the project forward. That has required some hard thinking about the short-term goals of the project, and how to approach them. For a project that involves neurobiology, the biggest gap is a dearth of information regarding the layout of the nervous system Although there is some literature on Sacoglossan anatomy, the description of the nervous system stops at the circumesophageal nerve ring. It is time to know more.
In order to understand the nervous system, we need to do some staining and microscopy. That would be significantly easier if the animals could be observed in wholemount, rather than having to dissect or section them. But the adults are too big! Juveniles, however, would be perfect, but how to obtain them?
It took a little while, but it dawned on me that we could make juveniles. The slugs are laying egg masses regularly, and they are developing perfectly well. On top of that, the veligers are lecithotrophic and settle on Bryopsis in less than a week! We just need to collect egg masses and grow them out in dishes, and then provide conditions for settling.
Egg mass in a dish: Check!
Incubator to maintain a constant temperature. Unfortunately, the one we have available does not like to hold 26 degrees C, so a bookshelf in the office will have to do.
The good news is that the embryos do not seem to mind the conditions in the office, and are developing nicely. Photos and videos to follow.