Hello readers! I can’t believe that it is week six already, It feels as if we started just yesterday. This week I took a step away form the swim study and focused in on studying the sizes of the nauplii. In most other species of parasitic barnacles males are typically larger than females. This is generally believed to be related to the sexes differing roles in reproduction. Once the larvae molt into cyprids the female goes in search of an un-parasitized host crab, which are generally in abundance. The male on the other hand has a much more difficult challenge. He must find a crab that has already been parasitized by a female which hasn't already been fertilized by another male. Needless to say, the odds are stacked against him. Since they do not feed and have to spend a longer period of time in the plankton the males have larger energy reserves in the form of lipid stores, resulting in a relatively larger larvae. This dimorphism among the two sexes is usually first observed in the naupliar stages of most rhizocephalan species. Since each brood of larvae released from the adults are believed to be entirely one sex, I began measuring the average size of the second stage nauplii in various broods in an attempt to distinguish the two sexes. Among six cohorts I saw no variation in size in the second instar, suggesting that there is no size difference between the sexes in this species. To see if this is the case throughout the entire developmental process of the larvae I measured two cohorts of cyprids. Interestingly, I saw a 15% difference in the size of the cohorts. I am currently culturing more cohorts in order to increase my sample size. If the averages support the hypothesis that there is a size difference in larvae, I may go back to the later stages of the nauplii to see if the size difference occurs later in the naupliar molts or solely in the cyprid. Only more tests will tell.
I made great progress this week at OIMB. I began the swimming study and spent lots of time observing my nauplii under the dissection scope. While I was hoping that this would help provide some answers about the function of their flotation collar, it only led to a million other questions. From my observations I was able to learn a little about their swimming behavior. All of them have a high affinity for the surface, wherever they are suspended in the water column they always slowly swimming towards the surface. They will generally take two to three strokes upward, then stop and drift downwards with their ventral side up for a bit. Usually they don’t get very far, typically sinking slightly farther than the distance they just swam upwards. Then they might swim for more strikes and cover a greater distance upward. Whenever when they are able to make it towards the surface their swimming pattern changes drastically. Once they where within a few strokes of the surface they reorient with their ventral side down and swim just below the surface in a more continuous motion.
To gain a better understanding of the roll that the flotation collar plays in the swimming behaviors of the nauplii, I attempted to remove it. I did so with the help of a set of thin wire probes. Since the collar only physically attaches to the posterior end of the larvae I was able to insert the probe in between the collar and the anterior end of the body and pry off the collar. The collar could then slide down the length of the probe with the larvae still attached By flicking the probe the nauplus would be freed from the collar with no apparent damage. When I observed the collar free larvae swim, I immediately noticed both differences and similarities with the collared larvae. For instance, they still sank ventral side up. This tells me that it isn't the collar that is responsible for this orientation, but rather the swimming appendages. I also observed that when they reached the surface water their orientation relative to the surface was much different. They where much more perpendicular to the surface rather than horizontal. The absence of the collar alters their interaction with the water surface. While I may not yet definitively know what this interaction is or its purpose, with further observations and testing I will hopefully soon find out!
We had another exciting week over here at OIMB. On Saturday our grad student MacKenna took us crabbing off of the boathouse dock. We loaded the crab rings up with some fish scraps and tossed them in. Over a few hours we caught several dozen red rock crabs. The ones we kept we brought back to the kitchen and MacKenna taught us how to clean and cook them. To no surprise they where delicious! Later that night my family flew in from California and rented a cabin on Tenmile lake. It was wonderful to be able to see them for a while. I got the chance to show them the beautiful Oregon landscape and all the cool things I’ve been working on over the last few weeks in the Emlet Lab.
As the week began it came time for us to present our research project proposals. Working on the proposal was helpful for organizing my ideas on paper. I have now decided that along with the molting study, I will also be looking at the sinking rates and swimming behaviors of the nauplii. One of the interesting physical characteristics of parasitic barnacle larvae is the presence of what has been described as a flotation collar. The flotation collar is a fluid filled ring that wraps around the larvae, it is shed and is regrown with each instar. Its exact purpose is not definitely known, but I have hypothesized that it has something to do with energy conservations. Since parasitic barnacle larvae do not feed at all they must be very efficient with whatever energy stores they are born with. By closely observing things such as their sinking rate and swimming behaviors, I may be able to better understand the collars role. In addition to this I have also worked on a better culturing technique for growing my barnacle larvae. To house the larvae, I cut the bottoms off small plastic beakers and replaced the bottoms with fine mesh that will allow water to pass through but keep the larvae inside. The containers allow me to move the larvae to be examined without having to handle them as much. It was also really interesting to hear everyone else’s projects in detail. It seems like everyone is working so hard and learning a lot on their topic. I’m excited to see how they all turn out at the end of the summer.
Friday we all hit the road to Eugene to visit UO main campus. We got a tour of the biological science labs at UO and got to take an inside look at some of their work. I got really excited in one of the labs that where working on the genetics of stickleback fish. They showed us their storage room which they had hundreds of live fish they where using for study. It was a very impressive set up.
On our day off we decided to end the weekend at the sand dunes. We didn’t have much of a plan and ended up a little lost. Fortunately a kind stranger directed us to a lake that was at the base of a enormous sand dune! We found it eventually and WOW! It really was enormous. We had a great time there together swimming in the lake and exploring the dunes. It amazes me how diverse Oregon is.
We had quite an adventurous weekend here at OIMB. On Saturday we set sail on the R/V Pluteus to go dredging off the coast. The dredge is heavy weighted net that is sent down to the sea floor via a cable attached to the boat. As the boat trawls around the net gathers whatever lays along its path on the sea floor. As excited as I was to go and collect some deeper water specimens, I have a history of sea sickness and was naturally a little apprehensive about the trip. I managed through the first hour and a half as we made our way out to sea, although as soon as we stopped to begin the dredge we where left rocking up and down in the ocean. Within a few minutes I was the first of us to chum the water and proceed to six or seven more times over the next three hours. Despite this, the trip was defiantly made worth it by all of the amazing stuff that we pulled up! We managed to collect some large basket stars, a beautiful leather star and even a small octopus.
The rest of the weekend flew by and before I knew it the Fourth of July was here. We all had the day off and went to Sunset Bay for the OIMB BBQ with everyone. We ate a feast, played volleyball and had the annual OIMB egg toss, which Elena and I killed by the way. All the interns finished the day off by making our way to the water front in downtown Coos Bay for the fireworks! We found the perfect spot on one of the docks right on the water.
Following the fourth it was back to work. On Wednesday I had an exciting development in the Peltogaster culture; 7 of my nauplii molted into cyprids! For those who don’t know the cyprid is the last stage of the barnacle larval development. They kind of resemble a coffee bean in shape with little protruding hairs on one end that they use to swim around with. Unlike normal barnacle cyprids which seek out a nice rock to settle on, the job of the parasitic barnacle cyprids is to seek out a viable host to parasitize. My success in growing these guys through their napuliar stage is a great mile stone in my work towards a greater understanding of their development.
This week at the Oregon Institute of Marine Biology I have begun to develop my research project. I decided that I would study the larvae of parasitic barnacles. While traditionally people think of barnacles simply as those little sharp lumpy things that encrust the coastline the parasitic barnacles that I am studying live much more dynamic lives. Instead of sitting on a rock all day and filtering through water to feed the adults leave their hard exoskeletons and infects the bodies of their fellow crustacean from which they obtains all of there nutrients. While the two adult forms of these barnacles are strikingly different form one another,their larvae have remained relatively the same.
After learning what I could about the larvae of parasitic barnacles and the similarities they share with their non-parasitic kin I decided that I would focus on researching the unique characteristics that separate them. The research that I plan on conducting will help to give science a better understanding of the naupliar larval stages in these barnacles. The nauplii have several unique feature that have not been sufficiently studies. For example, I would like to know how many larval stages (instars) or molts my species has before it metamorphoses and begins seeking out a host. I also want to learn if there is any correlation between developmental stage and the volume of the their lipid deposits. Unlike most barnacle larvae of typical barnacles the larvae of the parasites do not feed. This means that all of their metabolic energy must be provided to them from their mother during development. Considering this, I have hypothesized that the volume of the lipid stores should decease as the larvae develop.
To begin studying this we collected some hermit crabs from mussel point and checked them for the parasites so that I could have newly hatched larvae to study back at OIMB. The field work, I must say it a lot of fun. We drove up the road to a secluded spot then hiked through the wood for several minutes before coming upon a bluff which we had to scale down to get to the point. Once down there I quickly learned why they call it mussel point. The entire surface of the rock is covered in a seas of mussels! Back at the lab, I patiently waited for the eggs to hatch over the course of several days. It took a lot longer than I had anticipated, to the point I was getting worried that they where never going to hatch, but at last they finally did! I couldn’t even tell you how excited I was so see that little tiny spec swimming around in the beaker! Once I had enough to work with, I put the larvae in individual containers and began to could their molts each day as they developed. Dr. Emlet also gave me a crash course in how to take amazing pictures of them using the microscopes we have here in the lab. I think that it’s really amazing being to photograph something thats nearly invisible to the naked eye in such detail. It’s a new skill that I am very happy to be learning. Like the nauplii I am hoping to develop quite a bit myself over the next few weeks.