Surrounded by eight Nagas from the Immortal Realm's early stages, even someone from the fifth layer of the Immortal Realm and with a powerful heritage as Saria shouldn't be really calm.
If those eight captains attacked at the same time, she could block two of them, yet the other six could hit her. And even if her treasures and natural defenses blocked that damage, it would be nearly impossible to prevent at least one of them from harming her.
And after one of them hurt her, the others would keep attacking until they suppressed her with brute force. Even if some of them died, they could actually defeat the great Mermaid Princess.
With that thought in mind, those eight Naga captains try to take Saria's concentration down with intimidating threats before attacking with everything they have.