EARLY DEVELOPMENT OF THE TEN-POUNDER 



641 



may merely reflect individual variation. I have 

 not attempted to fit a regression line to the early 

 metamorphic larvae because of the narrow size 

 range involved. For late metamorphic larvae and 

 juveniles to a size of about 138 mm., the distance 

 from snout to insertion of pelvic fin increases 

 0.500 mm. per millimeter increase in standard 

 length (fig. 30, table 11). Extension of the re- 

 gression line beyond 138 mm. suggests the relation 

 is constant from the late metamorphic period to 

 adult, 



LABORATORY GROWTH EXPERIMENTS 



Three early metamorphic (shrinking) larvae 

 were reared through metamorphosis, and several 

 late metamorphic larvae were reared to juveniles. 

 Water from the location of capture of the fish was 

 used, and an inch of washed builder s sand was 

 placed in 4-gallon aquaria. The water was aerated 

 but never changed, and uneaten food and excre- 

 ment were siphoned off regularly. The water level 

 in the aquaria was maintained by adding distilled 



water as necessary. Water salinity was checked 

 periodically, and water temperatures were checked 

 daily (more frequently during periods of extreme 

 heat). Occasionally a bacterial growth (which 

 smelled of hydrogen sulfide) covered the sand, and 

 it was necessary to move the water and fish from 

 one aquarium to another. In such cases the water 

 was strained through No. 20 silk bolting cloth. 



Feeding habits. — Specimens were fed once daily 

 from the beginning of the experiments on April 

 10 to August 25, and two feedings were made daily 

 from August 25 to conclusion of the experiments 

 on October 1 (fig. 31) . Early metamorphic larvae 

 readily ate brine, shrimp (Artemia sp.), often in 

 such quantities that the digestive tract in vicinity 

 of the air bladder would be distended. No special 

 care was exercised to exclude unhatched shrimp 

 eggs when feeding shrimp to the larvae, and these 

 were often eaten (but apparently not digested). 



Late metamorphic larvae readily took pieces of 

 shrimp (Penaeus sp.) , small, live killifish (Fundu- 

 7u.s sp.), and mosquito fish (Gambusia sp.), and 



130 

 120 

 110 



.100 



5 

 z 90 



fe 80 



Ll) 



- 1 70 



Q 



cr 



g 60 



z 

 < 



40 

 30 

 20 



--9- 



l I I l 



'  



I I I I 1 



APRIL 



MAY 



JUNE 



JULY 



AUG. 



SEPT. 



OCT. 



Figure 31. — Growth of laboratory-reared specimens. Standard length measurements for Individual specimens are con- 

 nected to indicate individual growth rates. Numbers associated with growth lines refer to specimen numbers in 

 table 12. 



