When they were getting near to the place where the adult dragon turtle was trapped, they saw a large army of Merfolk idling there. The reason they were standing by was that the enclosed tunnel where they trapped the dragon turtle wasn't big enough to hold all of them. If all of them went in, there would be hardly any space to maneuver. They would become easy targets for the more physically powerful dragon turtle.
Hence, these merfolk took turns going inside. If one of the merfolk inside died, the one from outside would go through the gaps and take over the deceased one's place. The merfolk were using their own lives to wear the dragon turtle one.
When the merfolk children had been successfully rescued, John sent a message to Bowler to let him inform Ama. Of course, there was a chance that Ama decided to pull back after learning the children were safe. However, John didn't think the sea mother would do so.