He's an American Pit Bull Terrier. Possibly mixed with manatee.
Can you see the resemblance?
Here are some other reasons that I believe Arnold may be part manatee.
1. Manatees are quite gentle. So is Arnold.
2. Manatees are agile. Arnold has taken some Agility classes.
3. Manatees often have scars due to boat collisions. Arnold has scars too.
4. Manatees like to eat plants. Arnold does too.
5. Manatees spend most of their time feeding, resting or traveling. So does Arnold.
All in all, I think it's safe to say that Arnold is definitely part manatee. He's being fostered by the trainer who is working with Ziggy and me. She claims he is 100% pure American Pit Bull Terrier. Her dog, Jack, is Arnold's littermate, which is how she ended up fostering Arnold when his family had to move to Ohio -to a city that doesn't allow pit bulls. I haven't seen Jack yet, so I'm not sure if he looks like Arnold. But if he does, I might have to give her the bad news that her dog is also part manatee.
In spite of his dubious heritage, Arnold has done quite well for himself so far. He has been Temperament tested and certified through the American Temperament Test Society. He knows basic obedience (both on and off leash) and is currently enrolled in class and working towards his AKC Canine Good Citizenship. Now if he can just find a home with a family who doesn't mind his mixed-species heritage, he'll be all set!