They slowly swim up to Boat, jump on it and drill a hole in 3 seconds that result to a boat leak draining 1 /s.
They are neutral against the player. If attacked they will fight back, delaying the drilling process during the time of the fight. If they are killed before the end of the drilling, no leak is formed.
After drilling they go back into water and stay neutral for 30s. When killed they reappear after 90s.
They will feed on logs, boards, twigs, living logs left in the water, by leaping out of the water and eating one item per jump, they seem to prioritise items left in the water and will go toward them rather than ships.