Jellyfish taphonomy

Jellyfish taphonomy, a photo by hallucygenia on Flickr.

One of the nice things about being a palaeontologist is that fun things quite often qualify as work. For example, a trip to the beach offers an opportunity to make observations on modern marine ecosystems and examine natural taphonomic experiments. To anyone else this may look like peering into rock pools, picking up seaweed and carefully turning over rotting jellyfish, but we know better.

We recently visited Abereiddy Bay in South Wales. I have wanted to go there for a long time, because it’s a very famous site for graptolites. Not only does it have fossils, but also public toilets, interesting insects, rock pools, dead jellyfish and a van selling snacks. This makes it an ideal field location, the only difficulty being deciding what to look at first. We started with the insects, moved on to the fossils, then the snack van, then rock pools, then more fossils, and finally walked along the sandy part of the beach to look at the jellyfish.

Jellyfish, being about as soft-bodied as it is possible to be, aren't common in the fossil record. Most palaeontologists never find one in their entire careers! Seeing the dead jellyfish strewn around the beach, we decided to see look at the impressions they had left in the sand, in the hope of being able to recognise similar structures in the fossil record.

This is the jellyfish itself, or what is left of it. The tentacles are gone (eaten or rotted away), but the bell is more or less intact. (This photo was taken after we had examined the impression it had left in the sand.)