The Mola mola (moonfish), which lives in tropical and temperate waters, has a flattened body with a rounded shape -almost disc-shaped- and, instead of a caudal fin, has a rounded tail similar to a rudder, it was considered until now the heaviest bone fish in the world. In fact, it appears in the Guinness Book of Records as such. It is true that there are sharks of greater dimensions than this fish crossing the oceans, but the skeletons of the sharks are not made of bone, but of cartilage.
It had been established that this species – you can see a specimen in the image of this article – had the world record for the heaviest bone fish taking into account the characteristics of a specimen captured in 1996 on the Japanese coasts of Kamogawa, Chiba.
The specimen in question had a mass of 2,300 kilograms and measured about 2.72 meters in length. However, after a more exhaustive and recent examination of the characteristics of the different species of moonfish through photographs and specimens, as well as the analysis of more than a thousand documents -among them, they were half a millennium old-, has come to the conclusion that the fish, worthy of the first place in the aforementioned ranking , was not really a Mola mola , but a mola alexandrini .
Two type specimens of ‘Mola alexandrini’ (left) and ‘Mola mola’ (right).
The Mola alexandrini specimens are distinguished from those of the other species of sunfish – the Mola mola and the Mola tecta – by certain specific morphological features that can be observed in adults, such as, for example, a protuberance on the head – speculation by which also has received the name of moonfish with an irregular head – and a different chin and tail.
The study has been carried out by a team of Japanese researchers led by Etsuro Sawai, who is an expert in moonfish and works at the University of Hiroshima, and his results have recently appeared in the journal Ichthyological Research , published by Springer.
There must be bigger
Sawai is convinced that we will see how this record is surpassed in the future, since he is sure that there must be live examples of Mola alexandrini of greater size in the oceans. In this way, back in 2004, a female measuring 3.32 meters in length was captured on the Japanese island of Aji (Miyagi). However, it can not be considered the heaviest in the world because the mass of this marine giant was not measured.
It is not easy to have a copy of this type to carry out a scientific study because, due to its enormous dimensions, they are difficult to catch and also to be transported to be submitted to the morphological and genetic exams that researchers need to carry out. . But if there is one thing that this research makes clear is that we still have much to discover and rediscover the mysteries that enclose the oceans of our planet.