|
Found in tropical seas, the best know species of shepherd fish is known as the man-of-war fish or driftfish. They are found in most tropical areas staying close within the confines of their protectors reaching arms. These common names are derived from the shepherd fish’s amazing habit of spending much of its life drifting along within the stinging tentacles of the Portuguese man-of-war. Scientist have been puzzled by the name given to this fish, especially since it acts more like a flock of sheep being kept in line by this jelly-like fish. The shepherd fish feed on the zooplankton that collects on the tentacles and gonads of the Portuguese man-of-war making their actions appear more like that of sheep than the shepherd.
Found in the Nomeidae family from the Perciformes order, the shepherd fish is classified as a ray-finned fish. The shepherd fish is considered one of the smaller marine fish with an approximate length fewer than four inches. Shepherd fish have sacs along the back part of their throats that are lined with folds of skin. Each fold encloses a bone structure that supports the skin, which is covered with teeth. The outer skin of the shepherd fish is rather dull in color with either large uneven spots or stripes. This fish is equipped with a rather large pelvic fin that in some species is around three inches in length. Interestingly, the pelvic fin on the shepherd fish will fold inward much like a flag and then tucked away in a groove on the underside. Of the three genera of this fish, Cabriens, Psenes, and Nomeus, the latter has been studied to a greater extent since this genus is most often found with the Portuguese man-of-war. While the protector of the shepherd fish has stinging structures that can paralyze most small fish, the shepherd fish remain immune to the sting even though this jelly-like creature occasionally eats them. It is believed that, like other species of fish that live within the confines of stinging sea life, this only occurs when the shepherd fish become diseased. It is believed that some species of this fish may live with other species of the Portuguese man-of-war even though this has not yet been confirmed.
Like their protectors, the shepherd fish can be found offshore but when the
Portuguese man-of-war drifts with the wind into coastal waters they are often discovered within its tentacles. Fishermen pulling in their nets from the deeper waters have often been known to bring in several shepherd fish each time a Portuguese man-of-war becomes entangled in their nets. Although little is known of the spawning habits of the shepherd fish it is known that the juveniles of this species prefer to swim in the open waters of coastal areas, as well as, off shore, while the adults can be found in deeper waters. When the relationship between the shepherd fish and the Portuguese man-of-war have been studied it is speculated that the possible connection between these two might be in the attraction the shepherd fish has for other fish that prey on them. As the predators swim in to grab the shepherd fish, the jellyfish paralyses the predator. Studies suggest that the Portuguese man-of-war, which is known for capturing more prey than it can eat, may pass on tiny tidbits of its meal to the shepherd fish.
|
| |
