Bony fish have a swim bladder, a gas filled sac. The swim bladder originates as part of the belly. The swim bladder aids in creating an equilibrium with what is going on inside the fish and the surrounding water.
Some fish have a bladder that is part of the respiratory system, called an air bladder. It even creates a drumming sound. Croaker, red drum and black drum are part of the group.
Fish that have a skeleton made of cartilage do not have a swim bladder.
Do you have another great question? Check out www.beachchairscientist.com and enter let us know or e-mail beachchairscientist@gmail.com!
ripping apart prey. This may seem like it will hurt, but, a shark’s entire skeleton is made out of 
The electrosensory organ are useful for traveling far distances in the open ocean. It is like a internal GPS system. (I am not sure if it comes with a funny British accent like the one in my uncle’s car though.)
The Atlantic wolffish (Anarhichas lupus) may look rather frightening, but, the fish will only harm you if it is out of water. This is rather understandable since it is out of its natural habitat. It prefers to live on rocky bottoms of the ocean floor in very deep, cold waters.
What people are saying …