Cetacea and two (external) limbs that are modified into flippers. Though not as flexible or agile as seals, cetaceans can swim very quickly, with the killer whale able to travel at in short bursts and the fin whale able to cruise at . Dolphins are able to make very tight turns while swimming at high speeds. The hindlimbs of cetaceans are internal, and are thought to be vestigial. Baleen whales have short hairs on their mouth, unlike the toothed whales. Cetaceans have well-developed senses—their eyesight and hearing are adapted for both air and water, and baleen whales have a tactile system
What Is and What Should Never Be (Supernatural) creepy look to it". He was pleased to see Smith and Palicki return, and found the character of Carmen to be "a nice addition to the family". Don Williams of BuddyTV agreed, and ranked the episode third in his list of the best episodes of the first three seasons. Deeming it the best standalone episode, he noted that it "can be embraced by anyone who enjoys clever writing, great acting, or a shirtless Jensen Ackles". General Specific Notes What Is and What Should Never Be (Supernatural) "What Is and What Should Never Be" is the twentieth episode of the paranormal