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-- S u n f i s h f a m i l y --
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| Q 1. | ||
| What fish has bones so soft that they may be cut with a knife? |
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| Q 2. | ||
| Recently I found a fish on the Oregon Coast which was of a peculiar shape, rounded and appearing to have no tail. Could this be an ocean sunfish? I have heard that this fish only inhabits tropical waters. |
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| Q 3. | ||
| Why is the ocean sunfish called by that name? It is very unlike our freshwater sunfish. |
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| Q 4. | ||
| What is the difference between the sharp tail mola and the ocean sunfish? |
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| Q 5. | ||
| How large does the giant ocean sunfish grow to be? |
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| Q 6. | ||
| On a trip to the Perlas Islands in the Bay of Panama, we encountered very calm seas and spotted many fins breaking the surface. On approaching more closely, we saw among the sharks and sailfish a fish I have never seen before. It was about ten feet long and the fin stuck up three feet from the body. The body itself was about 18 inches in diameter and cylindrical. The tail fin resembled the wing of a delta-winged aircraft and pas about five feet from tip to tip. We got a very good look at it and have since decided that it was some kind of sunfish. However, it does not seem to resemble any of the sunfishes I have heard about. Can you shed any light on this? |
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| Q 7. | ||
| In certain years, ocean sunfish seem to be plentiful in the Pacific off the coast of southern California. It appears that these fish would be easy to capture with harpoon or spear. Will they take artificial lures or natural bait? Are they considered game fighters on rod and reel? Are they edible? |
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| Q 8. | ||
| In Sea Secrets, Vol. 11, No.8, you state that "ocean sunfish eat jellyfish." I am sure that you are aware of the sea nettle problem in Chesapeake Bay. Have sunfish ever displayed selectivity in their predation on coelenterate species? Have sunfish ever been observed in the upper Chesapeake? Would you consider their introduction as a possible means of reducing the sea nettle population? |
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| Q 9. | ||
| I have seen what I believe is called a headfish at Port Hueneme, California. Approximately, it weighed 20 pounds and was 2 feet in length and 8 to 10 inches in both height and width. It was gray in color. Can you identify this fish? |
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| Q 10. | ||
| While trolling for salmon several years ago off the coast of Washington State, I thought I saw a large ocean sunfish jump completely out of the water. Is this fish commonly found in cool waters? Also, is it capable of such powerful leaps? |
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| Q&A 1. | What fish has bones so soft that they may be cut with a knife? |
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| This is the giant ocean sunfish, Mola mola. In addition to its mammoth size and bulk (10-foot examples may weigh more than a ton), this fish is noted for its extremely sluggish movements and its habit of resting on its side on the sea surface, apparently “sunning” itself, which accounts for its common name. For all its vast weight, the sunfish has flabby flesh and bones of a soft, cheesy consistency, and subsists largely upon a diet of jellyfish. It is sometimes hunted for the oil in its liver, but otherwise the ocean sunfish is worthless commercially. |
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| Q&A 2. | Recently I found a fish on the Oregon Coast which was of a peculiar shape, rounded and appearing to have no tail. Could this be an ocean sunfish? I have heard that this fish only inhabits tropical waters. |
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| It is quite possible that it was an ocean sunfish (Mola mola). Although this fish, normally of tropical seas, reaches a weight of over 2,000 pounds, it is a weak swimmer and leads a planktonic existence, being transported from place to place by ocean currents. Frequently specimens of this fish on the Atlantic coast are carried into cold northern waters by the Gulf Stream, and finally washed ashore in a freezing or numb condition. A more elongated form of the sunfish (Ranzania truncata) is also found in 'warm seas throughout the world. Both these fishes have a curious “chopped-off” appearance, due to the peculiar form of the fringe-like tail fin. |
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| Q&A 3. | Why is the ocean sunfish called by that name? It is very unlike our freshwater sunfish. Columbia, South Carolina |
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| The ocean sunfish (Mola mola) is so-called because of its habit of lying at the surface almost motionless, apparently sunning itself. Since the ocean sunfish and its relatives are practically all head, they are also called head-fishes. |
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| Q&A 4. | What is the difference between the sharp tail mola and the ocean sunfish? Riviera Beach, Florida |
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| Both the sharptail mola (Mola lanceolata) and the ocean sunfish, or headfish (Mola mola), are members of the ocean sunfish family. They are alike in general characteristics except that the sharptail mola, a rare form not seen as commonly as the headfish, has a pointed tail with large dark brown spots on it. These strange-looking fishes are pelagic. Mola mola is more widely distributed, occurring as far north as Nova Scotia and the Gulf of St. Lawrence, while the sharptail mola restricts itself to tropical and temperate seas. Although they are large, the ocean sunfishes are related to the small fishes of the porcupine fish, puffer and filefish groups. Sea Frontiers for February, 1961, contained an informative article on Mola mola, "The Fish That is All Head." |
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| Q&A 5. | How large does the giant ocean sunfish grow to be? Miami, Florida |
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| There are four species of the genus Mola, all of which reach large size. These animals are higher than they are long and the largest specimen of each species (according to a 1951 review) follows below: Mola lanceolatus 10 feet by 11 feet 3 inches Mola oxyuropterus 7 feet Mola ramsayi 9 feet 8 inches Mola mola 10 feet by 11 feet Accurate weights on such giant fishes are difficult to come by. The 9 foot 8 inch individual was said to have weighed 31/2 tons. One specimen of Mola mola that measured 8 feet 6 inches weighed 1410 kilograms (or approximately 3,102 pounds) and this weight at least seems to have been accurately taken. The ocean sunfishes rank with the sturgeons as the largest of the bony fishes, with the blue marlin, black marlin, and the bluefin tuna not far behind. |
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| Q&A 6. | On a trip to the Perlas Islands in the Bay of Panama, we encountered very calm seas and spotted many fins breaking the surface. On approaching more closely, we saw among the sharks and sailfish a fish I have never seen before. It was about ten feet long and the fin stuck up three feet from the body. The body itself was about 18 inches in diameter and cylindrical. The tail fin resembled the wing of a delta-winged aircraft and pas about five feet from tip to tip. We got a very good look at it and have since decided that it was some kind of sunfish. However, it does not seem to resemble any of the sunfishes I have heard about. Can you shed any light on this? Fort Amadur, Canal Zone |
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| We believe that you did, in fact, see one of the ocean sunfishes, of which three types occur in your area. The one called Ranzania is quite elongate, although we have not heard of it reaching ten feet. This is not impossible, for we know little of this species. The delta effect you mention is achieved by the high, posterior dorsal and anal fins and the absence of a caudal (or tail) fin, this last being replaced by a posterior cartilaginous keel that serves as a rudder. |
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| Q&A 7. | In certain years, ocean sunfish seem to be plentiful in the Pacific off the coast of southern California. It appears that these fish would be easy to capture with harpoon or spear. Will they take artificial lures or natural bait? Are they considered game fighters on rod and reel? Are they edible? Bakersfield, California |
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| There would appear to be little value in catching these fish by harpoon or rod and reel. The flesh is edible, but not of a high grade. The ocean sunfish is not an extremely active swimmer, virtually planktonic, in fact, and you can expect about as much fight from it as you would from a rubber boot. Sunfish may attain a weight of over 2,000 pounds, so boating one would take considerable effort and would probably not be worth your while. Little is known about their feeding habits, except that they eat jellyfish. Their distribution is variable, as you have noticed. It is most likely dependent on the changing patterns of wind and current. |
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| Q&A 8. | In Sea Secrets, Vol. 11, No.8, you state that "ocean sunfish eat jellyfish." I am sure that you are aware of the sea nettle problem in Chesapeake Bay. Have sunfish ever displayed selectivity in their predation on coelenterate species? Have sunfish ever been observed in the upper Chesapeake? Would you consider their introduction as a possible means of reducing the sea nettle population? Washington, D.C. |
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| The ocean sunfish is worldwide in distribution, but favors tropical and warm temperate waters. Although it is true that they feed on jellyfishes to a very considerable extent, the introduction of the ocean sunfish into the Chesapeake Bay region is totally impractical. In the first place, the ocean sunfish is strictly an oceanic species. In the second place, it does not do well in cool waters. In the third place, they could not possibly make any significant inroads in the population of the sea nettle or any other jellyfish. |
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| Q&A 9. | I have seen what I believe is called a headfish at Port Hueneme, California. Approximately, it weighed 20 pounds and was 2 feet in length and 8 to 10 inches in both height and width. It was gray in color. Can you identify this fish? Simi, California |
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| The headfish is better known as the ocean sunfish. There are a number of species all of which reach a large size. The common ocean sunfish Mola mola, when full grown, has been measured at 11 feet in length and weighed nearly 2,000 pounds. It feeds primarily on jellyfish and other soft-bodied marine invertebrates. Ocean sunfish are of no commercial value, but are so curious in appearance that they excite interest wherever they wash ashore or come into shallow water. They prefer tropical or warm temperate waters. Although awkward in appearance, they have been observed in Florida waters as capable swimmers, skulling with the large dorsal and anal fins. Off Monterey, California, they have been observed as sluggish in movement, probably because they were numbed by the cold water or diseased. Further information is given in "Mola Mola Go to the Cleaners," Sea Frontiers, Vol. 13, No.2, March-April, 1967, and "The Fish That is All Head," Sea Frontiers, Vol. 7, No.1, February, 1961. |
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| Q&A 10. | While trolling for salmon several years ago off the coast of Washington State, I thought I saw a large ocean sunfish jump completely out of the water. Is this fish commonly found in cool waters? Also, is it capable of such powerful leaps? Brookline, Massachusetts |
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| Yes. The ocean sunfish, or headfish (Mala mala) is found worldwide in temperate, as well as tropical, seas. In waters off the Pacific coast of North America, it may be found as far north as British Columbia. The ocean sunfish typically is a pelagic, or open-ocean, species; however, it does occasionally wander into coastal waters, most likely in pursuit of some favorite prey. The oval-shaped ocean sunfish is capable of jumping out of the water, according to A Field Guide to Pacific Coast Fishes of North America (Houghton Mifflin Company, 1983). At first glance, this may seem unlikely, since this fish does not have a caudal fin, or tail, with which to propel itself. The blunt rear end of the ocean sunfish consists of only a scalloped, leathery flap. Observations in tropical waters indicate, however, that a healthy, unstressed ocean sunfish is capable of strong swimming. For propulsion, this odd-shaped species apparently relies on the sculling power of its long dorsal and anal fins. Although there are many accounts of the ocean sunfish lolling at the sea surface, it is now believed that this sluggish behavior is more typical of stunned or dying individuals. Cool water temperatures may induce this behavior and eventually lead to thermal shock and death. Another explanation is that the ocean sunfish may get stung by jellyfishes, one of its preferred foods. Similar behavior has been observed in the leatherback turtle (Dermochelys coriacea), which also eats jellyfishes. |
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Rosenstiel School of Marine & Atmospheric Science Library
University of Miami, FL USA 4600 Rickenbacker Causeway, Miami, Florida 33149 Phone: 305 421 4060 Fax: 305 421 9306 E-mail: libcirc@rsmas.miami.edu |
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