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-- D a m s e l f i s h e s --
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| Q 1. | ||
| Is it true that some fishes live inside sea anemones? |
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| Q 2. | ||
| What is the small blackish fish that sometimes chases other larger fish about the rocks in the Florida Keys area? |
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| Q 3. | ||
| What fish is green when young and bright red when adult? |
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| Q 4. | ||
| I have noticed a small fish, about 2 to 4 inches long, with black and yellow bars on its sides, that is very common around pilings and docks in the Fort Lauderdale area. Can you tell me what this fish is and something about its habits? |
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| Q 5. | ||
| What is the literal meaning of the scientific name of the sergeant-major, Abudefduf saxatilis? |
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| Q 6. | ||
| I recently fed my sea anemone a bloodfin which it ate but, later, the anemone refused to eat a dead clownfish (anemonefish). Also, my live clownfish are unharmed when they swim among the anemones tentacles. How do anemones tell the difference between fishes? |
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| Q 7. | ||
| While diving off Key Largo, Florida, we saw a small, colorful fish that we could not identify. It was about 1/2 inch long, had a beautiful blue-gray body, a bright orange dorsal fin and back, and a large blue-ringed black spot on its dorsal fin. Can you identify the fish for me? |
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| Q 8. | ||
| While skin diving in local waters, I cornered a garibaldi in a cave, and it made a loud noise. Is this an unusual behavior? |
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| Q 9. | ||
| While snorkeling in Micronesian waters, we observed that large schools of damselfishes (Chromis caerulea and Pomacentrus pavo) will gather around us if we produce bubbles in the water. They do not seem to be as attracted to the bubbles as much as they are to the paths from which the bubbles have arisen. What exactly is attracting these fishes? |
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| Q&A 1. | Is it true that some fishes live inside sea anemones? |
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| Yes, a number of small Pacific fishes belonging to the Family Pomacentridae and all brilliantly colored live inside the stomach cavity of the sea anemone. Ordinarily, the anemone will sting to death and devour any small sea animals with which it may come in contact, but the sea anemone fishes apparently enjoy complete immunity from the sting. One of the sea anemone fishes, Amphiprion persula, is bright orange in color, its body crossed by three white bars bordered with black. This species is said to make an excellent aquarium pet. |
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| Q&A 2. | What is the small blackish fish that sometimes chases other larger fish about the rocks in the Florida Keys area? |
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| This is the dusky damselfish, Pomocentrus fuscus, a small, active fish with a fearless disposition. Like its beautiful blue and yellow relative the beau gregory, P. leucostictus, the brown gregory will not hesitate to drive away a snapper, pinfish, grunt, or any other larger fish that may venture too close to the gregory's own particular niche in the rocks or under a coral head. Both the brown and the beau gregory make particularly hardy aquarium fishes, though they are typically aggressive toward other fishes. |
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| Q&A 3. | What fish is green when young and bright red when adult? |
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| This is the garibaldi or "marine goldfish", (Hypsypops rubicundus), which is abundant in the clear water off the rocky coasts of California. The garibaldi is one of the largest of the great family of damselfishes (Pomacentridae), which are conspicuous, though small, inhabitants of coral reefs and warm shore waters generally. Local members of this family include the beau gregory, (Eupomacentrus), and the serpeant-major, (Abudefduf). |
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| Q&A 4. | I have noticed a small fish, about 2 to 4 inches long, with black and yellow bars on its sides, that is very common around pilings and docks in the Fort Lauderdale area. Can you tell me what this fish is and something about its habits? Fort Lauderdale, Florida |
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| This fish, commonly known as the sergeant major (Abudefduf saxatilis), is also called the cockeye pilot or convict fish. This attractive fish is common in south Florida, and occurs on both coasts of tropical America from Uruguay to Florida, and is even seen on rare occasions as far north as Rhode Island. It reaches a length of about 6 inches. The sergeant major is mainly a shallow water species and seldom enters water deeper than 15 feet. Spawning occurs from June to August. The eggs are adhesive and stick to a rock or piling and are guarded by the male parent. Usually the eggs rest slightly below an overhanging coral, protected by the male's wild lunges at intruding fishes. Incubation of the eggs takes 5 or 6 days. It feeds on small crustaceans such as copepods, and on algae. The sergeant major is an inquisitive and pugnacious fish, darting everywhere among coral or reefs. It is sometimes solitary but more often swims in schools. |
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| Q&A 5. | What is the literal meaning of the scientific name of the sergeant-major, Abudefduf saxatilis? Miami, Florida |
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| The little banded damselfish known as the sergeant-major is quite common in tropical water around rocks and reefs. Its generic name, Abudefduf, is from Arabic, and indicates a fish with prominent sides: "Abu" means father or possessor. “Def” means “side,” with “defduf” an intensive plural. The specific name, saxatilis, is a commonly used name for fishes and means "a rock dweller." |
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| Q&A 6. | I recently fed my sea anemone a bloodfin which it ate but, later, the anemone refused to eat a dead clownfish (anemonefish). Also, my live clownfish are unharmed when they swim among the anemones tentacles. How do anemones tell the difference between fishes? Fairfield,New Jersey |
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| The mechanism by which anemonefishes are rendered immune to the sting of their anemone host has long been studied. The general opinion is that the immunity factor, a chemical that inhibits triggering of the anemone's feeding response, occurs in the slimy coating on the fish. The bloodfin, lacking this chemical, was eaten. A freshly dead anemonefish, however, would still possess the chemical and thus be rejected. This can be demonstrated quite easily. If another anemonefish in the aquarium dies, carefully wipe off all of its mucous coating and offer it to the anemone. It is likely that there will be a complete change in the behavior of the anemone, and it will accept the fish. Further information is given in Anemonefishes by G. Allen (Tropical Fish Hobbyist, Inc., Jersey City, New Jersey, 1972), which is available at most pet stores. A more technical source of information is "Observations on the Symbiosis of the Sea Anemone Stoichactis and the Pomacentrid Fish Amphiprion percula" by Davenport and Norris (Biological Bulletin, 115:397-410). |
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| Q&A 7. | While diving off Key Largo, Florida, we saw a small, colorful fish that we could not identify. It was about 1/2 inch long, had a beautiful blue-gray body, a bright orange dorsal fin and back, and a large blue-ringed black spot on its dorsal fin. Can you identify the fish for me? Haines City, Florida |
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| The fish you saw was a very small juvenile of the dusky damselfish (Eupomacentrus dorsopunicans). As the fish matures, approaching its adult length of about 4 inches, its colors darken until it assumes a uniform gray-black coloration. Such a color change with maturity is typical of not only the damselfishes but also many other species of reef fishes as well. |
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| Q&A 8. | While skin diving in local waters, I cornered a garibaldi in a cave, and it made a loud noise. Is this an unusual behavior? Capistrano Beach, California |
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| No. The garibaldi (Hypsypops rubicundus) is a territorial fish and will emit thumping and popping sounds to warn off intruders. A member of the damselfish family (Pomacentridae), the garibaldi is often extremely pugnacious in defense of its territory. Even females approaching a male's territory to spawn are not immune to threat displays and sounds. Inhabiting waters from Monterey, California to Magdalena Bay, Mexico, the garibaldi prefers rocky bottoms with crevices and holes that offer shelter and is found as deep as about 100 feet. It may reach a length of12 to 14 inches, and itsbrilliant orange coloration, coupled with an aggressive nature, makes it an easy target for collectors. In the State of California, however, the garibaldi is totally protected by law. |
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| Q&A 9. | While snorkeling in Micronesian waters, we observed that large schools of damselfishes (Chromis caerulea and Pomacentrus pavo) will gather around us if we produce bubbles in the water. They do not seem to be as attracted to the bubbles as much as they are to the paths from which the bubbles have arisen. What exactly is attracting these fishes? Majuro, Marshall Islands |
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| The schooling damselfishes that you observed are probably planktivorous and may identify the bubbles with floating plankton, according to Michael Schmale of the University of Miami. The fishes may be searching the stream of tiny bubbles that typically follow in the path of the larger bubbles rising to the surface. These very small bubbles may be mistaken for food items (at least initially) by these fishes. |
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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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