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Scientists finally identify giant sunfish larva and they're not giant at all

From little things, big things grow.

Steph Panecasio Former Editor
Steph Panecasio was an Editor based in Sydney, Australia. She knows a lot about the intersection of death, technology and culture. She's a fantasy geek who covers science, digital trends, video games, subcultures and more. Outside work, you'll most likely find her rewatching Lord of the Rings or listening to D&D podcasts.
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Steph Panecasio
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The larval specimen isn't quite so giant as its adult counterpart.

 Kerryn Parkinson

The giant Bump-head Sunfish, or Mola alexandrini, is a whopper. It's one of the largest fish in the world, with some reaching up to three meters, or 9.8 feet, in length. Animal Crossing fans might recognize it as one of the biggest fish you can collect in-game.

For a long time, scientists struggled to identify its larval form, partly because there simply weren't many to be found. Now they've finally managed to find the larvae for the first time, but they're far from the giants expected.

As part of a study led by the Australian Museum, a team of scientists in Australia and New Zealand were finally able to genetically identify the fish, analyzing specimens collected in 2017 by the CSIRO RV Investigator and preserved in alcohol -- but the larval specimen itself was tiny.

As a result of the unexpected size, the identification process was particularly difficult -- features normally used to identify adults aren't visible in larval specimens so it required considerable further analysis. 

Giant sunfish

The Mola mola, a variety of giant sunfish, can grow up to almost 10 feet long.

 Daniel Botelho / Barcroft Media via Getty Images

"Using the resources of the Australian Museum's Genomics Laboratory, we were able to conduct DNA analysis on one of the specimens which was preserved in alcohol." said Marianne Nyegaard, sunfish expert and lead on the study, in a statement. 

"A genetic ID of one of these larvae is incredibly important but only one step on the long journey towards describing the early ontogeny of all three Mola species -- an endeavour which will require global collaboration. If we want to protect these marine giants we need to understand their whole life history and that includes knowing what the larvae look like and where they occur."

Despite holding the record for highest potential fecundity, or ability to produce offspring, at 300 million ova in a single female, the lack of larvae thus far has made this identification process incredibly significant.

"Given sunfish are so incredibly fecund, it is an enigma why their eggs have never been found in the wild and why sunfish larvae are so few and far between -- where are they?" Nyegaard asks.