Posts Tagged: sea slug
Progression of Generations
A matriarch fades away, but the next generation reaches maturity.
At this point, it is a familiar cycle. They start out as a members of an egg mass, with thousands of their siblings. After they hatch, a lucky few dozen or maybe a hundred settle down and feed, selected mostly on the basis of luck. Once they start feeding, they grow rapidly, and a smaller, luckier group gets to go home to Box of Slugs 2. These will be allowed to get large and produce the next generation. And so on.
The previous generation has now come to an end. Several slugs from a brood laid in early January 2019 were placed in the tank on May 1.
Matriarch in her prime. July 1, 2019.
After growing to the usual big size, and laying many clutches of eggs over several months, the last of the group started to fade in late January 2020.
Elysia clarki at one year old. Hatched about 1/25/19, photographed 2/2/20. Note yellow parapodia and faded green body.
The biology underlying the change is unknown, at least to me, but I assume that the slugs fail to maintain or replenish their chloroplasts for some reason. Regardless of the cause, it seems to be a one-way street, and the old Elysia become more yellow, shrink, and start to look unhealthy.
Even in her last days, the old female appeared to feed on the available Bryopsis alongside her daughters, but she was unable to either absorb or process the food. Within a few days, she had disappeared. When a body is almost all water, it does not last long after death. She lived for over a year, which is not close to the record of two years reported by Pierce and colleagues, but is a pretty good life for a sea slug.
Fortunately, life also involves renewals. Over the summer and fall, the slugs produced thousands of eggs, and some of the offspring have matured to produce eggs of their own.
A pair of young slugs from a brood laid on 9/24/19 has produced their first clutch of eggs. As is usually the case, the first egg mass is smallish, maybe a few hundred eggs, but the size will rapidly increase. Production of the first eggs at four months of age is also consistent with previous observations.
So we are, once again, coming full circle. I need to sit down at some point and count how many generations have passed since the first hatchlings survived and grew into baby slugs, but it is satisfying that the group can keep itself going.
New Space!
After a long, tiring semester, we have moved into a new location in a shiny new building.
The Biomedical Sciences and Engineering building opened to great hoopla in November. Local and state bigwigs participated in the ribbon cutting, but, more importantly, so did some Biological Sciences students.
During all the hubbub, the students in the Cell Biology Lab course were going full speed in their new cell culture facility upstairs. A few even made their way into a Washington Post story about the event.
Although the building was officially open, it has token a while for it to be truly ready for use. Even now, there are contractors coming and going to put the finishing touches on the structure, and some necessities, such as ice machines are on the way.
Nonetheless, we made the move to our new space last week. It has taken months of preparation to have the spaces ready for the equipment, and the equipment ready for the spaces. We have been running Cell Biology, Neurobiology, and Physics labs all in the same room, so it will be luxurious to have two large, well laid-out lab spaces and associated preparation areas.
The most important space for the slug project is the new “preserved specimen” room. Someone must have decided that we would be dissecting cadavers, so we have a prep room devoted to dead things, and point exhausts over the lab benches to ventilate fumes from preservatives.
Since we have no plans to store pickled carcasses, the preserved specimen room will make an excellent “live specimen” room. The room is separate from the rest of the lab, so animals can be kept away from chemicals, and it has marine grade shelving perfect for aquaria.
On top of that, it has a floor sink for washing tanks and other equipment.
It took about two full days to set up the plumbing, to move the slug and algae tanks, and to get the control system set back up. Big thanks to Paul, Kevin, and the rest of the IT crew for helping me to get the controller connected to the local network.
The wiring is still a bit messy, but that can wait until I get my office and the two labs unpacked. Meantime, there are about a dozen slugs enjoying their new home.
The slugs will soon be joined by the earthworms, crickets, and crayfish for the Neurobiology Lab course.
Posts will probably continue to be sparse for a while. Elysia is still a wonderful system for teaching neurobiology, and I expect some of the students to use them for projects this semester. In the longer term, I am excited about developing multi-unit recording methods to study the activity many nerve cells at a time during sensory processing. However, that will be on hold for a little while while I work on a few other things.
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