Salema porgy

At ten meters, the Posidonia seagrass bed undulates like a field in the wind, and the school arrives from the side: one hundred, two hundred gold-striped fish, almost all of the same size. They do not flee. They plunge into the leaves, come back up, plunge again, and one understands that this disorder is a mechanism.

Large schools followed in seagrass beds graze in turn, some in the canopy, others hovering above, spending up to 90% of their time on a patch of less than 25 square meters. When they move away, the canopy is shorter.

And here begins the story that no one tells: in the most heavily grazed experimental plots, adult sea urchins are four to five times more exposed to their predators than sheltered by tall leaves. The salpa does not touch a sea urchin. It mows the shelter, and the predators do the rest.

Then there is the reputation that earned it its nickname. It has long been said that Rome served it for its effects — no surviving ancient text supports this. One documented case: a forty-year-old man hospitalized after a salpa meal on the Mediterranean coast, suffering from visual and auditory hallucinations, who recovered thirty-six hours later with no memory of the event. The responsible toxins are unknown. We only know that the fish in question are toxic for only a few weeks or months depending on the region, which suggests algae toxins — the very ones the salpa spends its life grazing on.