Hunt for Hemi'sLatest update December 19, 2018 Started on October 11, 2018
Scientists study strange animals for strange reasons.
In this case, we're searching for the hemichordate worm Schizocardium californicum, to understand how animals can build two different bodies (a larval and adult body) with the same genome.
For some reason, we've only ever found this animal in this small patch of mud in the Morro Bay State Park. For an animal that spawns 10,000 embryos in the water column, where do the larvae end up and is there a larger cryptic population of adult animals that we've missed?
With successful collecting trips come long experimental days, so things have been quite busy in the lab. Before it becomes a thing of the far-off, distant past I want to tell you about our two most recent collecting trips down to Morro Bay.
The first was back in mid-November with "Hunt for Hemi's" team member Auston Rutledge. Auston first joined our lab as an anemone tech after completing his undergraduate degree from CSU Monterey Bay and now works in the lab on a variety of projects and animals. It can always be a little nerve-wracking to return to our collecting site after a long while. Would that small pocket of PhD-thesis-essential worms still be there?
Low-and-behold the tide treated us well, but something we hadn't realized was how early it would get dark! We were able to dig for a couple of hours but then had to pack up quickly as the sun went down. One of the most interesting parts of the trip was finding what we think might be another species of hemichordate!
A bunch of different strange worms and wild creatures live in the thick sediment, but hemichordates typically stick out with their significantly larger size, particularly in diameter (around a couple millimeters). What we discovered was something that I naively at first thought could be some sort of albino version of Schizocardium, the hemichordate we've targeting down in Morro Bay. However, after getting back to the lab, taking some photos and consulting with a few of our colleagues who are experts in hemichordate taxonomy, we think this might be Balanoglossus occidentalis which has never been reported in this area. While we only found one individual this time, we're keeping our eyes out on future collections with the hopes of spawning and raising this species in the lab!
This last week brought a series of good low tides to the central California coast which allowed us to finally go out and do some collecting. The animals we work with seemingly live just at the edge of the low tide mark so unless we want to be up to our waist in water trying to look through a few feet of sloshing sea water, a low tide is our best bet.
Our first attempt at collecting took us out to Pigeon Point in Santa Cruz. We were looking a species of hemichordate that we hadn't found up in that area before, but were alerted to by our staff librarian. I had been asking him if there were any old reports about hemichordate collections or sightings and while we didn't find much else locally in the historical record he did find a sighting on a website called iNaturalist. Interestingly this "observation" was made as part of a larger "San Mateo County Bio-Blitz" showing the power citizen-science and crowd-sourcing in potentially impacting academic science.
So last Tuesday Paul Minor, a postdoc in our lab, and I made the trip up from Monterey in search of this potential acorn worm sighting. From the picture on the iNaturalist page we thought this could be hemichordate in the genus Saccoglossus. In our lab currently scientists who work on Saccoglossus are limited to field seasons that occur in Woods Hole, Massachusetts in May and September so finding a West Coast species would be a big deal!
Unfortunately, several hours of poking around shale and the small inlets of sea grass sand flats didn't lead to any discoveries. Whether or not this animal naturally lives here is still a mystery, potentially in lives in deeper water but this isn't currently something we can answer. Maybe in future! If nothing else it was some beautiful tidepooling.
Stay tuned for some updates about our collection trip the following day down to Morro Bay to look for the hemichordate Schizocardium!
So once we actually find these animals is that the end of the adventure?
No, because that's actually where most of it begins! A main focus of our research is studying metamorphosis a process that is similar to when a small caterpillar goes into chrysalis and emerges as a butterfly. Metamorphosis comes from the Greek “meta” to change and “morphe” to form and occurs across many phyla in the animal kingdom. We study this in Schizocardium californicum, an indirect developing hemichordate worm, which transforms from a small swimming planktonic balloon into a burrowing, muscular worm in a 24-48 hour time period.
An important aspect of our work involves visualization and microscopy. In the video below you'll see a live larvae, a stage we call the "tornaria" which has been embedded in agarose (molecular jello) and then stained with a dye that binds to DNA in the nucleus of cells.
Many animals in the ocean have distinct larval and adult body plans, what scientists call indirect development. We study the metamorphosis of Schizocardium californicum, an indirect developing deuterostome hemichordate worm, to gain a novel perspective on the processes that remodel and reshape the larval body plan.
The only place we have ever found the hemichordate Schizocardium californicum is in the Morro Bay State Marine Recreational Management Area of the coast of Central California. It has been thought that hemichordates require very specific conditions of sediment size, wave exposure etc., and their distribution is very patchy.
While we have made many collecting trips out to Morro Bay, we have often been stymied by the tide and on one occasion not found a single animal!
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