lOBSON ET AL.; CREPUSCULAR AND NOCTURNAL ACTIVITIES OF CALIFORNIA FISHES 



luring the afternoon had food in their guts, with 

 31 of these (88%) containing recently ingested 

 material. 



Fishes That Feed Primarily at Night 



The fishes that feed primarily at night clearly 

 are specialized to detect and capture prey in the 

 dark; nevertheless, under appropriate cir- 

 cumstances some also take prey during the day. 

 The predominantly nocturnal species considered 

 in this paper, w^ith certain of their visual charac- 

 teristics, are listed in Table 2. The following ac- 

 counts of diel activities highlights major features 

 of their crepuscular and nocturnal habits. 



Scorpaenidae: Scorpaena guttata 



The sculpin rests immobile among rocks during 

 the day (Figure 10) and generally is difficult to 

 discern owing to its cr5^tic features. Although 



Table 2. — Some southern Califomian fishes that feed primarily 

 at night, with the spectral absorbance maximum <Amax' °f 

 pigments extracted from their retinae. 



'See Table 1, footnote 1. 

 2See Table 1, footnote 2. 



Limbaugh (1955) noted S. guttata on open sandy 

 bottoms in deeper (to 60 m) water during the day, 

 at our study sites it generally occurred among 

 rocks. This fish seems well suited by its cryptic and 

 immobile attitude to ambush prey that have come 



Figure lO. — The morphology, coloration, and sedentary behavior of Scorpaena guttata render it virtually invisible on the seafloor. 

 Although many tropical scorpaenids use these features to advantage in ambushing prey during the day, S. guttata is primarily 

 nocturnal. 



15 



