Baby sharks, how strong is your skeleton?

The first part of my project involves testing the effects of warming and acidification on the embryonic development of small-spotted catshark. Now that we know whether they are growing well we’re going to look at a very specific issue linked to water acidification.

Small-spotted catsharks breathe by pumping oxygenated water through their gills. With ocean acidification, sharks filter more acidic water which reduces the pH of the blood. At the same time, it is regulated internally to remain at a constant level. These changes in the acid-base balance of the blood can have effects on other structures, such as mineralised structures like the vertebrae or jaw. But how do we know if their skeleton is strong?

X-ray microtomography (micro-CT) is a non-destructive imaging technique that uses X-rays to create cross-sectional images of an object, allowing for detailed three-dimensional reconstructions of its internal structure with high-resolution images of tiny structures. We used this technique to study the mineralised parts of newborn and juvenile small-spotted catsharks. Here we can clearly see the denticles covering the body of the newborn, the teeth, a mineralised structure surrounding the inner ear and the vertebrae.

Micro-CT of a small-spotted catshark.

These images had been used to carry out a whole range of measurements, including quantifying mineralisation density.