These researchers watched dead fish rot for 70 days—for science’s sake

Science can sometimes be a messy endeavor – not to mention “disgusting and smelly”. This is how British researchers described their experiences of observing the carcasses of sea bass as they rotted over a period of 70 days. In the process, they gained some fascinating insights into how (and why) the soft tissues of internal organs could be selectively preserved in the fossil record, according to new paper Published in the Journal of Paleontology.

Most fossils are bones, shells, teeth and other forms of “hard” tissue, but occasionally rare fossils that preserve soft tissues such as skin, muscles, organs or even the occasional eyeball are discovered. This could tell scientists so much about aspects of biology, ecology, and the evolution of such ancient organisms that skeletons alone could not convey. For example, earlier this year, Create researchers Highly detailed 3D model of a 365 million year old ammonite fossil from Jurassic period by combining advanced imaging techniques, Reveal the inner muscles that have not been observed before.

“One of the best ways soft tissues can turn into rocks is when they are replaced by 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 trying to understand how this process occurs – 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 frequently than other organs, such as the kidneys and gonads. There are two common hypotheses to explain this. The first is that different organs degrade at different rates, and that the pH of some organs will drop below the critical threshold of 6.4. When these organs degrade, they create a distinct pH microenvironment that increases the potential for those organs to ossify. Different minerals may form in different areas within the same carcass.

The second hypothesis is that tissue biochemistry plays a major role. Specifically, a diffuse pH environment forms within the body cavity and persists until the carcass breaks.

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

First, they purchased several adult European seabass from a local fishmonger as soon as possible after death (no more than 24-36 hours). Fish were kept on ice to slow decomposition but not frozen to avoid any cellular damage. Next, they inserted pH sensors at different locations on each of the six carcasses of seabass to target specific organs: the stomach, liver, intestine, and epaxial muscle. A fifth probe was used to monitor the pH of the surrounding environment between 1 and 2 mm of the carcass.