These researchers watched the dead fish rot for 70 days – for the sake of science

Science can sometimes be a messy endeavor – not to mention a “disgusting and smelly” activity. This is how British researchers described their experiments, during which they observed the carcasses of sea bass as they rotted for 70 days. In the process, they gained fascinating insights into how (and why) the soft tissues of internal organs can be selectively preserved in fossils. new page Published in the Journal of Paleontology.

Most fossils are bones, shells, teeth, and other “hard” tissues, but occasionally rare fossils are discovered that preserve soft tissues such as skin, muscles, organs, or even an eyeball. This can tell scientists so much about aspects of biology, ecology and evolution of ancient organisms that skeletons alone could not convey. At the beginning of the year, for example Create researchers Highly detailed 3D model of a 365 million year old ammonite fossil jura period by combining advanced imaging techniques, Explore the inner muscles which were not previously observed.

“One of the best ways to turn soft tissues into rocks is to replace them with a mineral called calcium phosphate (sometimes called apatite)” Co-author Thomas Clements said: from the University of Birmingham. “Scientists have been studying calcium phosphate for decades to understand how this process happens – but one question we don’t understand is why some internal organs seem more likely than others.”

Specifically, the muscles, stomach, and intestines tend to “phosphate” more often than other organs, such as the kidneys and gonads. There are two general hypotheses to explain this. The first is that different organs break down at different rates, and the pH of some organs drops below the critical threshold of 6.4. When these organs break down, they create a specific pH microenvironment that increases the possibility of organ ossification. Different minerals can form in different areas within the same carcass.

The second hypothesis is that tissue biochemistry plays an important role. Specifically, a diffuse pH environment develops in the body cavity and lasts until the carcass breaks down.

According to Clement and others. , no previous research has focused on documenting the pH gradients associated with the decomposition of specific anatomical features where the carcass decomposes in real time; Previous experiments have focused on recording pH fluctuations outside the carcass. So the team decided to correct this shortcoming by conducting experiments on decomposing fish, documenting how the pH gradient changed over two and a half months.

First, several mature European seabass were purchased from a local fishmonger as soon as possible (within 24-36 hours at most). Fish were kept on ice to slow decomposition but not frozen to avoid cell damage. They then placed pH sensors in different locations on the six seabass carcasses to target specific organs: the stomach, liver, intestines and epaxial muscles. A fifth probe was used to monitor the pH value of the surrounding environment between 1 and 2 mm of the carcass.

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