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Tackling the Ctenophores

July 10, 2013
The modern ctenophore Mertensia ovum (NOAA photograph)

The modern ctenophore Mertensia ovum (NOAA photograph)

For the past decade or so, my colleagues and I have been working to make sense of the fossils we are collecting from the William Lake site in central Manitoba (some research downloads can be found here, while a description of the fieldwork is here). Many of these specimens are difficult to interpret, as they represent groups that are poorly known elsewhere in the fossil record. We find ourselves doing endless photography and microscopic study, and we carry out a lot of literature research.

We also endeavour to examine comparative material whenever we can. Living and working in Winnipeg it can be difficult to carry out first-hand examination of modern marine organisms, since we are located almost as far from the ocean as you can get in North America! As a result, when I travel I try to visit collections elsewhere.

Fragmented specimens of the modern ctenophore Pleurobrachia sp., in a petri dish

Fragmented specimens of the modern ctenophore Pleurobrachia sp., in a petri dish

The fossils that have risen to the top of my “research heap” are odd little structures that show considerable evidence of being preserved ctenophores, or comb jellies. We have been working to image and document these, and have reached the stage where we need to finalize our interpretation of the various features so that a paper can be written.

I have acquired preserved modern comb jellies and carried out simple experiments to see what happens to them when they are desiccated on and in fine lime mud. The results were intriguing and consistent with the interpretation of our fossils, but we still need to look at specimens showing some of the diversity of modern ctenophores, and at some examples that are better preserved than those could be acquired through commercial channels (the broken ones above were received from a scientific supply house).

Anderson House, a former mansion converted into residence and dining hall by the Huntsman, is glimpsed through the evening fog

Anderson House, a former mansion converted into residence and dining hall by the Huntsman, is glimpsed through the evening fog

This quest has brought me, this week, to the Huntsman Marine Science Centre in St. Andrews, New Brunswick. The Huntsman maintains the Atlantic Reference Centre (ARC), which curates preserved examples of Canadian Atlantic marine life. The large collections include many groups, and I will be examining numerous examples of ctenophores and other “jellyfish.” I am also delighted to be returning to an institution where I spent some of the pleasantest weeks of my life, taking an undergraduate marine biology course, and I really don’t mind that St. Andrews is one of the prettiest towns in Canada!

I start on the collections tomorrow, and I hope to find things that make this visit worthy of a blog update …

© Graham Young, 2013

creek

2 Comments leave one →
  1. July 16, 2013 2:44 am

    I was really interested to see your article because, just a few weeks ago, I saw many large comb jellies swimming with moon jellyfish on the waterfront in Halifax, Nova Scotia. I had never seen them alive and in action before – only small ones washed up on the beach in the UK. I took photographs but none are clear enough to make a definite identification. However, I could see that they were three or four times as large as the sea gooseberries which were also present, and they seemed to have at least two shorter combs as well as longer ones. I tentatively thought they might be Common Northern Comb Jellies (Bolinopsis infundibulum). It is difficult to imagine that creatures so insubstantial and delicate could leave a trace in the fossil record. I hope you had a productive stay in St. Andrews and found what you were looking for in the collections. Have you thought of catching fresh ctenophores for your research?

    Jessica

    • Graham permalink*
      July 16, 2013 7:48 am

      Hi Jessica, many thanks for your thoughts. Yes, the stay in St. Andrews was very helpful, as they had a very large and fresh Pleurobrachia for me to dissect. I would love to catch fresh ctenophores for research, but the problem with that sort of creature is that you tend to see them when you aren’t looking for them, and vice versa! It is interesting about the comb jellies you saw. In the collection in St. Andrews, all the ones that weren’t Pleurobrachia seemed to belong to Beroe.

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