The Bottlenose Dolphin is the most common and well-known dolphin species. It inhabits warm and temperate seas worldwide and may be found in all but the Arctic and the Antarctic Oceans. Bottlenose Dolphins are grey, varying from dark grey at the top near the dorsal fin to very light grey and almost white at the underside. The salt water makes them hard to see both from above and below when swimming. The elongated upper and lower jaws give the animals their name of bottlenose. The real nose however is the blowhole on top of the head, and the nasal septum is visible when the blowhole is open. Their face shows a characteristic "smile". Adults range in length from six to thirteen feet and in weight from 330 to 1430 pounds with males being slightly longer and considerably heavier than females on average. The size of the dolphin appears to vary considerably with habitat. The flukes (lobes of the tail) and dorsal fin are formed of dense connective tissue and don't contain bones or muscle. The animal propels forward by moving the flukes up and down. The pectoral flippers at the sides of the body serve for steering. This series of "Marine Life Protection" proof one dollar coins has been a hit with collectors since the first coin was issued in 1992. It is hard to say whether the obverse or reverse is the most attractive, but they are becoming exceedingly hard to find. Palau was chosen as the location for the 10th season of the hit reality series Survivor, and this coin depicts regional marine life, as well as a beautiful mermaid. This One Dollar coin is legal tender and has been issued by authority of the government of Palau.