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Size of Young and Number Carried

mouth, eggs, male, cc and fish


It is to be regretted that no such full data can be given for larvae as for eggs carried by the gaff-topsail paterfamilias. Unfortunately but few lots of larvae were taken, and these larvae were rarely killed at the time of capture, but were kept that their behavior might be studied, their organogeny worked out, and drawings of them made.

On July 18, 1907, an 18-inch male was caught and from his mouth were taken 21 larvae. One of these, of average size, after being in 10 per cent formalin for 24 hours, measured: extreme length (point of snout to tip of upper lobe of caudal) 57 mm.; outside width over eyes 11.25 mm.; length of dorsal spine 14.75 mm.; yolk-slit, longitudinal measurement 18 mm., transverse 16.5 mm.

On July 7, 1908, an ovigerous male was taken in whose mouth were found 6 larvae measuring 53 to 55 mm. long over all. On July 21, 1910, 5 larva were taken from the mouth of a male, but unfortunately neither father nor young was measured. Young of about this stage are shown in figure 11, plate iv.

As to the size the young attain before leaving the shelter of the paternal mouth, fairly definite data can be given. In general it may be stated that departure does not occur until the fishlet is grown, i. e., until the yolk-sac has been inclosed by the body-walls. This a priori conclusion was verified when, on July 20, 1908, my fishermen brought in a young catfish which they had taken from the mouth of an adult some hours before. In this fish, which was about 4 inches long, the body-walls had completely closed over the yolk of which there was no outward sign save for a fine aldermanic curve in the abdominal region. The escape overboard of the little fish in the trans fer to my bucket forestalled the taking of any measurements. The fishermen (men in whom I have large confidence) told me that towards the close of a haul they had noticed one big catfish and a number of little ones swimming around in the net. The little ones got away but the big one was hastily secured and in his mouth was found the 4-inch young one referred to. A little catfish in this stage of devel opment is portrayed in figure 12, plate iv.

In this connection the following incident may be related, the narrator being long and favorably known to me. Mr. T. E. Adair says that

in the early nineties, he and his brother Charles were seining one day off the mouth of Wading Creek in Newport River, when their seine brought in a number of gaff-topsails. These spat out a lot of young some 2.5 or 3 inches long "with a great big yolk dividing the little fish in two." Then he and his brother both distinctly saw the old one open his mouth and the little ones swim into it. He then "took up the big one and poured out a double handful of young ones." In the section on size of mouth cavity, it was stated that 5 casts had been made but only 4 were described; the fifth cast was that of the mouth of the 18-inch male brooding 21 larva as previously noted (p.37). The volumetric displacement of one of these larva, for which measure ments have been made, was 4 c.c. That of a slightly smaller one was 3 c.c. scant. Thus the total volume of the 21, if they averaged 4 c.c., would be 84 c.c., or if 5 c.c., only 105 c.c., while the capacity of the mouth as shown by the plaster cast was 120 c.c.

In intimate relation with the number of eggs and young carried by an adult male is the question of how many eggs an adult female may extrude. The largest number of eggs gotten is 55 from the mouth of a 22-inch male. Only one adult female has ever been spawned. This fish is merely noted in my records as being very large (probably about the size of the male above) and from her were obtained 68 eggs. Whatever the facts for smaller fish, it would seem that the largest male does not carry in his great buccal cavity as many eggs as the largest adult female can produce. From which it seems probable that the fish are polyandrous as well as polygamous.

The data at hand indicate that not all the ova extruded are fertil ized, and it is quite probable that all the eggs fertilized are not hatched, and that all the young hatched are not matured. However, it would seem from my experiments that, when once the eggs are fertilized, the mortality in the paternal mouth is far less than in the best-regulated hatching-jars. Considerable data on this point have been previously given (Gudger, 1916).