Posts By Dave
Slug-tastic week!
Things do not get a whole lot more slug-errific around here than they were this week. There have been exciting developments in both boxes of slugs, and it feels like spring will be a good time for Elysia here in Maryland.
In Box of Slugs 1, the group of E. clarki that arrived from Carolina Biological in December has fattened up and started laying eggs. I hope this perfectly coiled mass symbolizes the beginning of a productive time for this setup. With a few new ideas, I think we should be producing small slugs by the dozen.
E. clarki eggs, deposited 1/27/15
Box of Slugs 2 is has been even more fun. The miniature slugs have been growing rapidly, moving quickly from tiny wiggly objects to small versions of their parents.The one below is looking very much like a proper E. clarki.
Baby slug January 27, 2015
Nonetheless, they are still babies. For a sense of scale, here is one of the youngsters perched above mom/dad on a Penicillus plant.
Growing youngster above presumptive parent in Box of Slugs 2.0
Finally, and possibly most exciting, KP Aquatics let me know that the had collected some E. crispata this week. As the project has developed, I have tried to find suppliers who can provide me with the three North American species, E. clarki, E. crispata, and E. diomedea. In the past, I have ordered “lettuce sea slugs” from various suppliers, and always received E. clarki. Don’t get me wrong, E. clarki is a wonderful species, but I was a bit frustrated that the suppliers did not seem very interested in which species they were shipping.
That was not the case with KP Aquatics. After they sent the first batch of clarki, which produced the lovely offspring pictured above, I corresponded with Kara, who seemed very interested in the differences between the species. It was refreshing that they truly wanted to understand the organisms that they collect.
So, Philipp emailed me this week that they had five crispata, and I decided I had to have them. Shipping went fine, despite the frigid temperatures, and they settled into the smorgasbord of Penicillus, Halimeda, Avrainvillea and hair algae without a hitch. Although I should love all slugs equally, I must say the new kids are the real beauties of the collection.
E. crispata in Box of Slugs 2.0
Baby Slugs Already!
As always, there has been plenty to keep us busy after our return from Bonaire, but we have had a little time to look in on the Boxes of slugs. Seahorses and slugs are doing their thing in B.o.S. 1.0, but no new egg masses or babies as yet.
In Box of Slugs 2.0, the new plants have been enjoying the nutrients and growing well. Unsurprisinlgly, hair algae (looks like Derbesia) has also been spreading exuberantly. Not great for aesthetics, but good for Elysia.
One nice development was the presence of a small egg cluster that appeared by the time we were back. Age is not known, but they will presumably hatch within the week. Not collecting these guys, because the tank may be conducive to the settling and maturation of little sluglets. Why would I think that? Keep scrolling down.
Eggs on Caulerpa prolifera in Box of Slugs 2.0
When I glanced at the tank yesterday, I saw some interesting shapes, and thought “goodness me, could it be?” Indeed it was, little wiggly guys with parapodia, rhinophores and chloroplasts! There appeared to be at least half a dozen of them.
Teeny Slug on Penicillus 1/25/15
Unfortunately, I only had the Canon Powershot SX30, which is unbeatable for taking photos of wildlife from a distance, but rather poor for macro photography. Will bring the Canon G12, home from the office to get some better photos. .
Tiny Slug in Box of Slugs 2.0, 1/25/15
A little math suggests that their eggs may have ridden in on one of the plants, rather than being deposited by the current residents. On average eggs from Box of Slugs 1.0 take about 16 days (16.7) to hatch, and then settle after another 3 – 4 days. The guys pictured above appear to be at least another week beyond that. The parents arrived on 1/5/15, and the babies were visible on 1/25, less than 3 weeks later, which seems like breakneck speed. The water temperature is a little warmer for this setup than for B.o.S. 1.0 (~25 C vs ~23 C), but it still seems a stretch for the eggs to be deposited, hatch, settle, and then grow to the point of being miniature slugs in such a short time.
Anyway, it is an exciting development, and I hope that the youngsters will avoid the hazards of tank life and grow to maturity.
Slugs of Bonaire
I know you have all been eagerly awaiting the most recent slug photos from our trip to Bonaire. We had hoped to find some of the less common species, such as E. ornata, E. subornata or E. picta, but efforts to find a local expert to help locate suitable habitats were not successful this time around. Apparently, not everyone is as fascinated by this marvelous genus of slugs as I am. I gave up rather quickly trying to explain that, yes, I know that lettuce slugs (E. crispata) are common on the western side of the island, and no, I am not looking for colorful nudibranchs. Easier to nod my head enthusiastically.
Nonetheless, there were plenty of E. crispata to be had, which was just marvelous. Here are a few of the little beauties we found. One characteristic of the species in the variability in color, and this group shows a little of the spectrum. The strobe failed early in the trip, but the slugs’ preference for shallow water provided the opportunity for available-light photography.
Below is a pastel green specimen, found at Margate Bay.
Light green E. crispata. Bonaire.
These two blue and green fellows were found huddled below a large gorgonian, next to a nice piece of fire coral. In the shallows of Red Beryl, one of our favorite sites at the south end of the island.
E. crispata and fire coral. Red Beryl, Bonaire
Below is “Tridachiasaurus,” the biggest slug I had ever seen. Hard to get a sense of scale in the photo, but notice the relative size of her rhinophores (normal sized rhinophores, dwarfed by a large body) and intense ruffling of her parapodia. Photographed at Andrea I, a nice dive site with relatively easy entry and exit.
Huge, ruffly E. crispata. Bonaire
Also at Andrea I, another blue and green specimen, showing the characteristic large, white spots on the midsection.
Blue E. crispata. Bonaire.
Here are a few other shots from among the hundreds. They may not be slugs, but it is my site, so I can post what I like.
Common Octopus, Bonaire
Green turtle. Dozing on windward side of Bonaire.
Tang Parade!
Box of Slugs 2.0 up and running
As described in Slugkeeping FAQ, one excellent way of having a box of slugs is to set it up as a refugium (a fish-free zone that allows proliferation of plants and small organisms) in line with a marine aquarium. The plants can make use of the nutrients (phosphate and nitrate) produced by the fish and food, reducing their concentrations in the display aquarium while providing food plants for the slugs. Further, supplementation of calcium and carbonate for corals will also support growth of calcareous algae, such as Halimeda or Penicillus. The only concern is avoiding pumps or strainers that the slugs will inevitably encounter and be killed.
A 27 gallon cube (20″ wide X 18″ deep X 20″ tall) was a good fit for the available space, and I found a used stand that fit with the decor reasonable well. To accommodate input from the coral reef tank, and overflow back to the sump, I drilled a couple of holes in the back, and added bulkheads plus fittings.Because the flow through the tank will be very low, there is no need for fancy overflow systems.
Holes for connection to reef tank.
Input from reef tank (left), drain to sump (right)
Then it was just a matter of adding sand for the plants. For a little topography, I added a large-ish piece of base rock. In case flow from the main tank circulation fails, there is also a Hydor heater/pump combination to act as a backup. It has a sponge attachment for the intake that ensures slug safety.
Box of Slugs 2.0
Nice thing about adding a tank to an established system is that it is ready for inhabitants. KP Aquatics (formerly SeaLife Inc) sent me a nice batch of macroalgae, and I indulged myself in a few photosynthetic gorgonians as well. The Elysia clarki settled in well.
Box of Slugs 2.0 with macroalgae and gorgonians
Away for a few more days
Greetings from Bonaire. Hoped to do some live blogging, but the new computer is down. Many exciting things to see here, as always, and we have some wonderful new photos of E.crispata to share when we can upload them.
Meantime, here is one of the new E. clarki that arrived in Box of Slugs 1.0 last week. Will bring real camera back to office next week for better photos.
New resident in Box of Slugs 1.0
Another small step…
For those who have an interest in keeping their own slugs, the Slugkeeping FAQ page is now live.
Fade Away
From time to time, one of the slugs starts to shrink and become pale, despite appearing to have normal appetite and behavior. Ultimately, the slug disappears without a trace. My assumption is that this signals senescence, and the greatly reduced slug becomes food for the boisterous collection of detritivores that dwells in the Box of Slugs.
Slug fading away 10/22/14
Over the past few weeks, the remaining slugs have all apparently succumbed. Although it’s a bit sad, one does not expect the little guys to live forever, especially since their ages on arrival were completely unknown. Living 5.5 months seems a bit short, but not ridiculously so. The production of a couple of clutches of eggs per slug per week for a few months may also have contributed to their demise. They appeared to have happy little slug lives, and taught us much.
There are new adults on the way from Carolina Biological, plans on the horizon for Box of Slugs II in a new location, and an upgraded culture facility (Box of Slugs 1.1) here at USG. Stay tuned for all that.
Seahorse Sculpture
Although there is activity behind the scenes, it continues to be quiet on the front page here. For the moment, enjoy a photo of a seahorse sculpture on Bainbridge Island, courtesy of Ann and Hans.
Seahorse Sculpture on Bainbridge Island
Baby Slug Bottleneck
Life cycle of Elysia clarki in the Box of Slugs
The slug colony, a.k.a. Box of Slugs, has been doing pretty well overall. The slugs have been eating, growing, mating, and laying eggs. The eggs have been hatching, and the veligers have settled as baby slugs. Of the many broods that have been deposited over the past few months, I have collected and hatched about a dozen, so producing juvenile slugs has become routine.
What has been puzzling and frustrating is that the baby slugs are not maturing beyond the first few days. They crawl happily among the macroalgae in the little dishes, but never seem to take in chloroplasts or develop parapodia or rhinophores. I have offered them both Bryopsis and Derbesia, two algal species that are supposedly their favorite first foods, and they appear to be attempting to eat, but the little guys never turn green.
A few observations may or may not be relevant. First, dumping too much Bryopsis into one of their dishes appears to cause immediate and permanent cessation of activity. The simplest interpretation is that, even though Elysia species have been reported to take advantage of the defensive compounds produced by their food plants, too much is simply too much. Also, even though I dip the algae in distilled water for 30-60 seconds before adding it to the cultures, the occasional amphipod, copepod or nasty looking worm sneaks in and may cause a ruckus.
In the end, there are hypotheses to be tested. In order of decreasing likelihood:
1. I am using the wrong food plants. Even though I am feeding species of Bryopsis and Derbesia, the algae were collected from aquaria, so their origin is unknown. I know that the parents love the species of Bryopsis that I am providing, but it may be more difficult for the juveniles to feed on.
2. Temperature. I am currently not controlling their temperature. They hatch on a bookshelf at about 23 degrees C, and then their dishes are moved to the top of the Box of Slugs to provide light when the algae are added. The temperature is probably a bit higher under the LEDs, but I have not measured it.
3. Light. They go from low to relatively high illumination when food plants are added. Maybe they don’t like the light. The little slugs move around happily enough, but who knows.
4. Chemistry. Aside from keeping salinity at 1.025, I do not test or change the water in the crystallization dishes. Given the tiny biomass and the presence of healthy algae, the possibility of waste nitrogen or phosphorous becoming a problem seems slim. Maybe they need to have their water changed to get rid of chemical secreted by the algae?
With finals almost over, I can give some thought to how to separate the variables and get past the roadblock.
Quiet days
Apologies for the radio silence, but little has been happening this past week. The most promising batch of baby slugs has largely disappeared while I was away for the holiday, although the next batch looks excellent. The November 12 clutch, which I have been documenting since it was deposited, has hatched. Unfortunately, I have not found an easy way to video veligers that refuse to stay in one field of view for any length of time. They will probably settle tomorrow, and will be photographed then.
Baby ponies have been hard to find. I rarely see them, but this little one appeared briefly before I left last week. A little more color perhaps, but quite the skinny little fish.
Week old baby seahorse 11/26/14
Tomorrow will be a good day for a little maintenance.
Recent Comments