Comparing a fossil jellyfish found at Solnhofen with jellyfish found stranded along the coast of a recent inter-tidal mudflat

This post is one in a series of posts which compares the depositional environment of the late Jurassic lithographic limestones at Solnhofen in Germany based on extracts from Solnhofen: A Study in Mesozoic Palaeontology with observations made at a modern inter-tidal mudflat at Ha Pak Nai, Deep Bay, New Territories, Hong Kong and proposes an inter-tidal mudflat origin for the examples cited.

This post compares comments on, and a photograph of a fossil jellyfish (Rhizostomites admirandus) found at Solnhofen with photographs of stranded jellyfish found along the coast at the inter-tidal mudflats at Ha Pak Nai, Deep Bay, Hong Kong.

It should be noted, there are individual jellyfish strandings at Ha Pak Nai year round, while mass strandings occur around October.

Extracts from: Solnhofen: A Study in Mesozoic Palaeontology

“These animals stopped functioning in hypersaline solutions because water is drawn osmotically from the tissues. The shriveled appearance of many Solnhofen jellyfish (especially those from Gungolding-Pfalzpaint area) is quite consistent with this idea of hypersalinity” (Barthel et al - Page 59).

“The weaker swimmers, or really floaters, lived in the quieter surface waters. Of these the jellyfish, and free-swimming hydrozoans and planktonic crinoids, were most numerous and most susceptible to being swept into the lagoon” (Barthel et al - Page 84).

“Amongst the early post-mortem features to develop was the osmotic wrinkling of normally turgid animals when bathed in these hypersaline solutions, as exemplified by some jellyfish” (Barthel et al - Page 90).

Photographs of jellyfish found stranded at Ha Pak Nai

(Scale where shown: 30 centimetre/12 inch ruler)

October 2009 - Mass strandings

  

Photographs of individual jellyfish in the mass strandings of October 2009. 

October 2009 - Jellyfish showing beginnings of dessication and burial.

June 2009 - Jellyfish showing effects of mild dessication (the haloes may be due to ant predation).

October 2009 - Jellyfish showing effects of advanced dessication.

References

Barthel, K.W., Swinburne, N.H.M., and Conway Morris, S. (1994). Solnhofen: A Study in Mesozoic Palaeontology. Cambridge University Press, Cambridge.