SEA BASS: WHAT'S IN A FISH?

The sea bass is a great example of a fish. Fishes are the largest (about 25,000 species) and most diverse group of animals with backbones; they come in every size and shape imaginable. But the sea bass has the characteristics of the most typical fish.  It has a streamlined oval body covered with scales, seven fins, a lateral line and gills for breathing.  It is cold-blooded, which means that it stays the same temperature as the water around it. 

Two fins on its back (the dorsal fins) and the fin on its belly (the anal fin) help steady the bass and keep it upright as it swims.  The tail or caudal fin moves side to side to propel it through the water.   Notice how the tail is rectangular; that shape gives the sea bass quick power so it can snatch its prey. A pair of pelvic fins and a pair of pectoral fins, one on each side, help it steer, brake and balance.

The lateral line--it runs along the side from the head to the tail--is a special "sixth sense" that fishes have to detect motion in water.  It helps them feel tiny changes in pressure from the motion of other creatures.  Sea bass breathe with gills, not lungs.  Under the opercle, or gill cover, are rows of very fine blood vessels.  The bass takes in water by opening and closing its mouth; then, as the water flows over the gills and back out to the sea, oxygen passes through to the blood.

This photo  was taken less than 3 miles from the NJ coast near the Jacques Cousteau Estuarine Research Reserve.  Courtesy Uwe Kils, http://krill.rutgers.edu.

Sea bass are an important food for people, and fishing for them is major source of money all along the Atlantic coast of the US. They are also important in the food chain of the ocean: they are eaten by bigger fish and eat smaller ones. Sea bass like rough bottoms, rocky ledges, wrecks, pilings... anything they can lurk around, then spring out to catch an unsuspecting lunch as it swims by.  Like most fish, they live on the continental shelf, within 20 miles of shore.