266 
Abstract— The feeding habits of the 
Mediterranean spiderfish, Bathypterois 
mediterraneus , the most abundant fish 
below 1000 m on the deep slope of the 
Catalan Sea (western Mediterranean), 
were studied. Samples were obtained 
at depths between 1000 and 2250 m. 
Diet was analyzed for two different size 
classes (immature and mature speci- 
mens) and three different bathymetric 
strata. The most important food items 
found were benthopelagic planktonic 
calanoid copepods. In juveniles from 
1800 to 2250 m, benthic tanaidaceans 
were secondary, whereas in the adults, 
mysids were secondary. At other depths, 
there were no secondary prey: calanoid 
copepods were consumed almost exclu- 
sively; other items were very scarce. 
Adults ingest larger amounts and sizes 
of prey than juveniles. The scarcity of 
resources below 1200-1400 m diversi- 
fied the diet, although it still primarily 
consisted of elements from the ben- 
thopelagic plankton. 
Manuscript accepted 12 September 2000. 
Fish. Bull. 99:266-274 (2001 ). 
Feeding ecology of the Mediterranean spiderfish, 
Bathypterois mediterraneus 
(Pisces: Chlorophthalmidae), 
on the western Mediterranean slope 
Maite Carrasson 
Jesus Matallanas 
Dpto. Biologia Animal, Biologia Vegetal y Ecologla 
Universidad Autonoma de Barcelona 
Bellaterra, E-08193 Barcelona, Spain 
E-mail address (for M Carrasson): Maite.Carrasson@uab.es 
The genus Bathypterois Gunther, 1878 
comprises a small group of benthic chlo- 
rophthalmid species adapted for life 
in the deep sea. The genus is circum- 
global at temperate latitudes (Sulak, 
1984a). Two species of Bathypterois are 
found in the Mediterranean: Bathypter- 
ois dubius and Bathypterois mediterra- 
neus (Bauchot, 1962). The presence of 
a third, Bathypterois gi'allator, based 
on underwater photographs, has been 
suggested by Sulak (1984a). The Medi- 
terranean spiderfish, Bathypterois med- 
iterraneus, is the only endemic species 
of the genus, and undoubtedly the most 
abundant in the Mediterranean (Sulak, 
1977; Bauchot, 1987). 
Some species of the genus Bathyp- 
terois, such as Bathypterois dubius, 
Bathypterois grallator, Bathypterois 
atricoloi', and Bathypterois viridensis, 
have been observed from submersibles 
(Church, 1971; Heezen and Hollister, 
1971; Saldanha, 1977; Jones and Su- 
lak, 1990; Chave and Mundy, 1994; 
Chave and Malahoff, 1998). The fish 
are benthic, rest on the bottom, and 
touch the sediment with their longest 
pelvic and caudal rays (Heezen and 
Hollister, 1971; Saldanha, 1977), while 
the long pectoral rays are directed for- 
wards over the head (Saldanha, 1977). 
Pectoral rays are likely used as sensory 
devices to detect the presence of plank- 
tonic prey, by both direct contact and 
chemoreception (Sulak, 1977). 
According to Sulak ( 1984a ), Bathypter- 
ois mediterraneus is benthic on the con- 
tinental slope and rise, at 260-2800 m. 
However, in the Catalan Sea (western 
Mediterranean), the species is restricted 
in its bathymetric distribution to depths 
greater than 748 nr (Stefanescu et al., 
1992a, 1994; Morales-Nin et al., 1996). 
Of the 31 different species of deep-wa- 
ter fish in the Catalan Sea (Stefanescu 
et al., 1992a), Bathypterois mediterra- 
neus is subdominant between 1000 and 
1 500 m, and dominant below this depth. 
At 1000-2250 m Bathypterois mediter- 
raneus is the fourth in importance for 
biomass of all fish (Stefanescu et al., 
1992a). This species aggregates (Stefan- 
escu et al., 1992a; Morales-Nin et al., 
1996), contrary to Sulak’s ( 1984a) obser- 
vation that it is usually solitary, but may 
aggregate occasionally. 
Knowledge of the biology of deep-sea 
fauna in the Mediterranean is limited. 
The feeding habits of some deep-water 
fish and decapod species in the Cat- 
alan Sea have been studied recently 
(Cartes and Sarda, 1989; Carrasson 
et al., 1992; Cartes and Abello, 1992; 
Cartes, 1993a, 1993b, 1993c). Informa- 
tion on Bathypterois mediterraneus bi- 
ology is limited and fragmentary. Data 
regarding growth and depth-size trends 
are given by Morales-Nin (1990), Ste- 
fanescu et al. (1992b), and Morales-Nin 
et al. (1996). The morphological and 
morphometric characteristics of the al- 
imentary tract and some generic data 
on the diet of this species have been 
reported by Carrasson and Matallanas 
(1990, 1994). 
