FISHERY BULLETIN: VOL. 71, NO. 2 



(1928); Cyprinidae by Szarski (1956); Spher- 

 oides niphobles by Ishida (1936); Scaridae and 

 Labridae by Gohar and Latif (1959). Both 

 morphological and physiological characters of 

 the stomachless fishes appear to be character- 

 istic of the Labridae. 



The morpholoy and histology of the entire 

 alimentary tract in the cunner were described 

 from the protrusible lip to the anal papillae. 

 A histochemical study was made on the gut, 

 i.e., the postpharyngeal portion of the alimen- 

 tary tract. Also, feeding habits and habitat, 

 gut contents, and the movement and digestion 

 of food were investigated. 



MATERIALS AND METHODS 



The fish were collected at East Point, Nahant, 

 Mass., from May to September 1970 and 1971. 

 Larger specimens, over 100 mm SL (standard 

 length), were taken by hook and line fishing 

 along the shore, and smaller ones in plankton 

 hauls, by bottom dredging, hand netting, and 

 rotenone poisoning in tide pools. Some speci- 

 mens were maintained in constant running 

 seawater aquaria and fed with mussels (Mytili- 

 dae). 



Histological and histochemical studies were 

 made after starvation (7-10 days) and after 

 feeding. Specimens less than 40 mm SL were 

 killed in 10% Formalin,^ larger ones by severing 

 the spinal cord and by intracoelomic injection 

 of Dilantin (sodium diphenylhydantoin, USP) 

 anesthetic (0.1 ml/10 g body weight). Tissues 

 were fixed with absolute acetone. Baker's For- 

 malin, Bouin's (also with seawater), Kelly's, 

 Hollande-Bouin's or Zenker's fixatives in order 

 to demonstrate specific cell types. After fixation, 

 dehydration was done in two ways: the standard 

 method of ethyl alcohol or from water to 

 Cellosolve (2-ethoxyethanol). Infiltration and 

 embedding were carried out using Steedman 

 polyester wax (1960); serial sections were cut 

 at 1 to 8 jU . A variety of routine histological 

 and histochemical stains were used, including 

 hematoxylins (Ehrlich's, Galigher's, Heiden- 

 hain's Iron Alum, Groat's) counterstained with 



^ Reference to trade names does not imply endorse- 

 ment by the National Marine Fisheries Service, NOAA. 



eosin or fast green, Giemsa (Mallory, 1944, in 

 Humason, 1967), Gomori's trichrome (1950, 

 in Humason 1967), Heidenhain's azan (1938, in 

 Humason, 1967), Masson's trichrome mixture 

 (Gurr, 1956, in Humason, 1967). Histochemical 

 methods included: alcian blue (Steedman, 1950; 

 modified by Mowry, 1956, 1963, in Humason, 

 1967), periodic acid Shiff's technique (McManns 

 and Mowry, 1960, in Humason, 1967), toluidine 

 blue (Lillie, 1929, in Humason, 1967). Acid 

 and alkaline phosphatase tests were done by 

 Gomori's modification according to Pearse 

 (1960). 



To determine the natural food and feeding 

 habits, gut contents were examined immediately 

 after capture, or specimens were frozen for 

 subsequent examination. Also the feeding habi- 

 tat was observed by SCUBA diving. Food move- 

 ment and digestion rates were observed in 

 specimens from 150 to 200 mm SL which 

 were fed whole, small mussels less than 20 mm 

 (shell length), or the visceral mass of larger 

 mussels. Gunners were either fed daily or were 

 starved for 7 days prior to experimentation. 

 Fish were allowed to feed voluntarily on a 

 cluster of mussels during the V2- to 1-hr periods. 

 Uneaten mussels and broken shells were re- 

 moved after the feeding period. Carmine, 

 Chinese ink, or ultramarine blue were in- 

 jected into the visceral mass as indicators. 

 Fishes were killed by severing the spinal cord 

 at the base of the skull, at 1-hr intervals from 

 to 36 hr after feeding. Autopsy was done 

 immediately after sacrificing the fish in order 

 to locate the position of the food. All pH values 

 of the gut lumen were determined from narrow 

 range pH papers. 



Ten adults (180-240 mm SL) and 6 juveniles 

 (30-34 mm SL) were used for histological and 

 histochemical studies, and 68 specimens (30- 

 300 mm SL) for analyses of gut contents. 



RESULT 



Morphology and Histology 

 of the Alimentary Tract 



As reported by previous authors for other 

 labrids (Barrington, 1942; Suyehiro, 1942; 

 Al-Hussaini, 1947b; Gohar and Latif, 1959, 



566 



