No.32 Bluefin tuna

It is a saltwater fish belonging to the mackerel family of the order Perchidae. It is found in the Pacific Ocean in the northern hemisphere and grows up to about 3 meters in length. It has grooves on its fins to eliminate irregularities when they are closed, and its scales are very small, so it has low water resistance and can swim at a maximum speed of about 100 km/h.
This specimen was CT scanned at the request of NHK Enterprises, Inc. as part of NHK E-television's “Gyogyotto Sakana★Star” project.
Giggle at Sakana★Star" program HP: https://www.nhk.jp/p/ts/P58QMGP4K1/

CT imaging revealed that the skeleton of the bluefin tuna is very similar to that of the chub mackerel, which belongs to the same family, but the bluefin tuna has a parietal foramen, a hole in the parietal bone. Bluefin tuna dive to a depth of about 400 meters in search of prey. It is thought that the structure of the parietal foramen was changed to protect the brain from water pressure during this process.