Eusociality, is the most sophisticated level of organization of sociality, is defined by the following characteristics: cooperative brood care, overlapping generations within a colony of adults, and a division of labor into reproductive and non-reproductive groups.
Eusociality is an incredibly successful evolutionary strategy; the Hymenoptera family is one of the most species abundant and one of the largest by biomass on the planet.
But Eusocial animals are small in size. The largest of the eusocial animals are the mole rats, which of course have exponentially smaller colony sizes than ants for example.
The reason for this is rather apparent in that a larger body mass necessitates more resources, but we do have a multitude of megafauna that’s lived in massive groups, just none of them eusocial.
I want to know if it would be possible to have megafauna exhibit eusocial traits, whether it is a roving herd that protects a central queen as it crosses grasslands or some sort of predatory fish school, I just want to know if you could ever get a decently sized eusocial animal.