Dorsal fins

The main building narrowed to a sharp point that cut into the sky like a dorsal fin throwing up ripples of cloud around four supporting towers. 

Escolar and oilfish belong to the Gempylidae (snake mackerel) family in the order Perciformes (Alexander et al., 2004 Nakamura and Parin, 1993). There are currently 24 species under 16 genera in Gempylidae, and they are all found in the marine environment (FishBase, 2008). All species in this family usually occur in very deep waters in tropical and subtropical seas (Nakamura and Parin, 1993). They have elongated and compressed body with isolated finlets after the anal and dorsal fins (Nakamura and Parin, 1993). 

Fish, reptiles, and amphibians are sometimes prepared as whole-body taxidermy mounts, but in collections they are most often preserved in 70% ethanol and water. Dried mounts prepared for display are often painted, since most of the natural pigments change or disappear when the animal dies. Mounted fish, particularly large ones, are often produced as a combination of natural and artificial parts. Large dorsal fins, such as those on sailfish and marlin, are often damaged and are recreated in wax or resin (older mounts) or fiberglass, masonite, or thick cardboard. 

Marlins are large fish with elongated, bill-like snouts, fairly high dorsal fins, and a streamlined body. 

The two species can be differentiated by their eye coloring, dorsal fins, and the position of their ventral keels. As its name infers, the goldeye has gold-colored eyes. Furthermore, the mooneye has 11-12 rays comprising its dorsal fin. The same fin on the goldeye has only 9 or 10 rays. Finally, while both the mooneye and the goldeye have a fleshy keel on their belly, known as a ventral keel, its position on each fish is different. On the mooneye, the ventral keel does not extend in front of its pelvic fins on the goldeye, it does. 

The fins of the ocean sunfish are distinctive there is a single long dorsal fin extending from the top and an equally long anal fin. The body ends abruptly with a low tail fin, and a rounded and wavy tail. The pointed-tailed sunfish (Mola lanceolata), has a tail drawn out into a point in the middle. The oblong-shaped sunfish Ranza-nia truncata) has a tail with a more rounded margin. 

Bony fish are outfitted with fins that facilitate maneuvering and positioning in the water. The fins, which are made of thin membranes supported by stiff pieces of cartilage, can be folded down or held upright. Fins are named for their location Dorsal fins are on the back, a caudal fin is at the tail, and an anal fin is on the ventral side. Two sets of lateral fins are located on the sides of the fish, the pectoral fins are toward the head, and the pelvic fins are near the tail. The caudal fin moves the fish forward in the water, and the others help change direction and maintain balance. 

Fig. 5.2 The special features of bony fish include bony scales (a), opercula (b), highly maneuverable fins (c), a tail with its upper and lower lobes usually of equal size (d), a swim bladder that adjusts the fish s buoyancy (e), nostrils (jj, pectoral fins (g), a pelvic fin (h), an anal fin (i), lateral lines (j), dorsal fins (k), and a stomach (l).

Members of the family Gobiesocidae are considered to be ray-finned fish because their fins have one spine and four or five rays. Each fish in the family has a single dorsal fin that is positioned nearer to the tail than to the head, as well as an anal... 

The eel-like bodies of gunnels have long dorsal fins and flexible lateral fins, so they swim back and forth in very much the same movement as snakes. The butterfish, a gunnel that can grow to be 10 inches (25.4 cm) long, is coated with mucus, an adaptation that most likely developed to reduce drag in water. 

Manatees and dugongs are the only sirenians. These docile, slow-moving herbivores lack a dorsal fin or hind limbs but are equipped with front limbs that move at the elbow, as well as with a flattened tail. Their powerful tails propel them through the water, while the front limbs act as paddles for steering. 

Color Adults in ocean or Great Lakes are steel-blue to slightly green on dorsal surface, sides brilliant silver, ventral surface white, small black spots on back, sides above lateral line, base of dorsal fin, and upper lobe of caudal fin. 

Dolphins live in tropical waters (10-32 °C) and their size is approximately in the range of 2-4 m and they weigh 150-200 kg. Dolphins are highly adaptable in regulating temperature. For example, in flukes, flippers, and dorsal fins, arteries are surrounded by veins to increase heat transfer and maintain body temperature. In addition, the heat transfer is very efficient because it is countercurrent (Fig. 4.4). 

The dorsal fin might help stability, but it also has an important role in body s thermoregulation. What can we learn from this Dolphins have different mechanisms and strategies to regulate temperature ... 

Fig. 4. A coronal section through the skin and scales anterior to the first dorsal fin of a hlacktip shark C. limhatus. Anterior is towards the left. The scales have been manually manipulated by a probe so that the three scales towards the right are erected to greater than 30°, whereas the scale on the extreme left is in the resting position. The picture was taken with a dissecting microscope at 400 X magnification and in-line digital camera. Image courtesy of Dr. Phil Motta (Professor of Biology, University of South Florida).

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