Though fish are our distant cousins, there are more differences than similarities between us. In today’s post, I’d like to explore the various characteristics that make a fish a fish—or not. Skeletal distinctions Of course, not all fish are the same and the oldest fish are not truly fish. True fish have bones somewhat like us, but not exactly. All of our bones are connected together by cartilage, but in fish, the fins are not connected to anything but muscle. The tail is connected to the spine, but none of the other fins are. Sharks and rays have no bones, only cartilage. Built-in buoyancy compensators The swim bladder in most fish (but not all) allows them to maintain neutral buoyancy, or the ability to stay in one place in the water without sinking. More: A Fishy Biology Lesson From Paul… More:
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