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Parasites

barracuda, found, fish, host and echeneis

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PARASITES.

From what has been said as to the food and manner of feeding of the big barracuda, it is to be expected that it would be the host of all sorts of entozoa, parasitic helminth worms, but strange to say such is not the case. Having myself paid no attention to such parasites in my specimens, I have naturally turned to the writings of Professor Edwin Linton. Fortunately Professor Linton has spent considerable time at Tortugas studying its parasitic entozoa, and among the fishes exam ined were numerous specimens of S. barracuda. In 1908 he notes that 3 large and 4 small barracudas were examined, and in these immature nematodes were found for the most part encysted in the viscera. Like wise a few trematodes were found. So few were parasites of all kinds that Linton notes: " It is perhaps worthy of remark that the great barracuda, which is a very voracious and predatory fish, appears to harbor but few parasites, either as a final or intermediate host. This conclusion is warranted also from the results of the examination of five barracuda in Bermuda in 1903. The largest Tortugas specimen measured about 1.5 meters in length; the Bermuda specimens were about half that length. It would be of interest to know whether the apparent immunity from parasites of the barracuda and other fish is correlated in any way with the digestive ferments." In his later paper dealing with the trematodes, Linton (1910) notes the examination of eight barracudas, in every one of which he found specimens of a new or at any rate undetermined species of ostomum. This seems to have been the only parasitic trematode which he found in the barracuda.

However, an Ascaris has been found by Linstow (1906) in Sphyra nura barracuda from Tasmania. Linstow's generic name is bly a misspelling of Sphyrcena. Other than the references given, no accounts of internal parasites of the barracuda have come to light.

The fish seems singularly free from such unwelcome guests.

We now turn to an animal which in the past has been considered as an ectoparasite to its hosts, the barracuda included. I have among my notes gravely worded accounts of the finding, when the so-called para sites had been removed, of places worn in the skin or scales of the host; further it has been accused of living on the blood of its host thus obtained through the skin; and, most preposterous of all, one account specifically states that when one had been removed from the bottom of the boat to which it had adhered, the planking was found to be injured. Reference is made to the sucking-fish, Echeneis nav,crates, for small forms of which the great barracuda sometimes acts as host. On July 4, 1914, while trolling east of Loggerhead Key, the writer took a barracuda 40.8 inches long. When hauled in it was very active and called for strong repressive measures before it was quieted.

When the miler was over there was found clinging to the deck the smallest example of Echeneis I had ever seen. This fish was about 4 inches long and had a most remarkable tail, plumose instead of crescent-shaped. It was carried to the laboratory and, as it seemed sick and the hour was late in the afternoon, it was put into an aquarium to be studied the next morning. When morning came it was gone and no trace of its whereabouts or its manner of going was ever found. Some two years later I was greatly interested to read in the " Memorias" of the Cuban ichthyologist, Poey (1856-58), the following description of a little Echeneis which he calls "E. sphyrcenarum, the sucker of the Picudas. " "This little fish has never been found up to the present time save only on the Sphynena picuda. It hides itself among its hosts' gills and escapes therefrom when the large fish is taken. The individual which I describe is 75 mm. long. In size [depth?] it scarcely exceeds a centimeter, since it is shrunken by concentrated alcohol and its body is greatly diminished. One sees, however, that its structures are all elongated. The eye is contained 5 times in the length of the head. The disk ends towards the anterior] third of the pectorals, and has on each side 10 lamellie furnished with spines in one rank alternately long and short. The mouth is homodont: the teeth of the jaws and vomer are cardiform, but the lower jaw shows on the outside a peculiar character; it projects, is a little enlarged, ends squarely, and bears on each side toward the point an external row of five hooks (crochets), strong, and pointed, remarkable for their development. The pectorals arise near the opercles, and between their points and the origin of the vertical fins the distance is equal to the length of the head. The unpaired fins are opposite each other and have the ordinary form. They arise at an equal distance from the point of the snout and the end of the tail, the point not being con sidered. This point, formed of the two middle rays, is times as long as the rest of the caudal, a character very distinctive of this species. The dried condition of my specimen forbids a count of the rays. The color is a very dark blue verging on black. The pectorals are white except at their bases. The two anterior points of the vertical fins are white, as are also the upper and lower edges of the caudal fin, but not the point which terminates it." One other reference may be cited just here: Laken, writing in 1878, speaks of an Echeneis lineata, a fish identical with Poey's E. sphyra' narum, which he found among the collections in the museum of Copen hagen. This was taken in the South Atlantic from a Sphyrcena barracuda. Liitken thinks that this particular Echeneis is to be found attached only to the sphyrmna.

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