(OOC: If it's okay, I'd like someone to give him a name in-character. I have no preference for the name, as long as it's however your character would see him.)
He was not put into existence to survive alone.
He didn't realize this at first. At first, he had not known the meaning of absolutely anything around him. From his birth, the panther cub's moist fur slick against the treacherous boards of the slum-ship from which he came; he was put at a disadvantage that would one day cost him his life. A vital sense with missing from him, the sense of hearing. He was completely ridden of it from his very beginning, and for this defect, he would suffer the fate of discommunication, confusion, and unawareness. He was not born a very healthy cub... and who knew what else stirred inside the fleeting newborn's head? What life did the unknown defects of his unhealthy birth have in store from him? Whatever that would be: he couldn't do it alone. His fate was written as plainly Darwin had written the tale of natural selection, he was going to have to help himself just as much as those around him would help him. A hard life came ahead of the cub. Nature told him and those around him he wouldn't be any use, but nature was defied here in more ways than one.
The man who had thrown him overboard was clearly no crewman who knew his way around a knot. The cub's eyes had been just practicing their first exposure to the scenic world, but it did not last for long before a harsh, calloused hand peeled him from the boards in which his tiny claws were caught. One had torn completely free, and in its absence it bled profusely. The panther cub, barely reaching the edges of a newborn, was then manhandled by his tiny frame into a small, flimsy black trash-bag. The cub couldn't comprehend what was happening as the world sealed with a single knot, and everything went dark. He had seen his siblings also meet the same fate inside the bag. He couldn't sense danger, but he couldn't sense his mother, either. Though... from the hours he had been by her side, he sensed no life in her, just the scent of decay that he didn't understand. The slum-ship had reeked of despair and death of all animals. That ship had been hell's version of Noah's Ark, and to meet his fate in the ocean inside this bag was truly a blessing to a big cat who had faced a horrible life there for long.
As if he was a newspaper flying from a bicycle, the man tossed him overboard the ship and into the inky water. The ship was short, so the fall didn't hurt him. He was beginning to feel sensations of fear as the water flowed and consumed his entire body. The fear got stronger and stronger, he could sense the mottled fear of his siblings as they drifted further away, but he couldn't hear them. He couldn't see them. He couldn't understand them. As a last resort, the cub went wild. The fear, one of his first negative emotions from the meager content he had experienced before, took him over as he began flailing inside the bag. Blood smeared the plastic of the bag from his claws that had been tattered by the boards. He flailed harder and harder, giving out thin wails and mewls that he couldn't hear, but ripped both naturally and painfully from his throat.
The tide had swept his siblings away. He could sense them no more as the water overtook them as their makeshift deathbeds floated away. The ship, as well, had gone from sight.
The cub, meanwhile, had to live to see his story through. So, fate granted him this, and only this: his flailing had worked, and he was now visible from a beach that was nearby.