Food of cave fishes 
31 
Table 2 The gut contents of Milyeringa veritas from the American Museum of Natural History collections. 'Fish N' and 
'Prey N' denotes the number of fish containing that prey item. 
Side of peninsula 
AMNH number (N) 
Contents 
West 
45497 (N=23) 
Prey N(%) Fish N(%) 
East 
48568 (N=16) 
Prey N(%) Fish N(%) 
No contents 
- 
8 (31) 
- 
4(21) 
Cockroaches 
1(5) 
1(4) 
9(53) 
7(37) 
Isopods (Armadillidae) 
14 (64) 
12 (46) 
2(12) 
2(11) 
Stygiocaris (shrimps) 
1 (5) 
1 (4) 
1 (6) 
1 (5) 
Crustacea (probably Stygiocaris) 
1(5) 
1(4) 
1(6) 
1(5) 
Trichopteran larvae 
1 (5) 
1 (4) 
2(12) 
2(11) 
Ants 
4(18) 
1(4) 
0(0) 
0(0) 
Unidentified insect parts 
“ 
1(4) 
0(0) 
0(0) 
Worms? 
0(0) 
0(0) 
1(6) 
2(11) 
Total 
22 
26 
16 
19 
the Cape Range peninsula and that of the prey 
items (Humphreys 1993a, 1993d; Knott 1993). 
Indeed, an undescribed species of syncarid 
crustacean of the genus Atopobathynella (H.K. 
Schminke, pers. comm.) (Parabathynellidae, 
Bathynellacea) is the only element in the 
stygofauna of the Cape Range peninsula (and 
Barrow Island) that is clearly Gondwanan (W.F. 
Humphreys, unpublished). 
Milyeringa veritas 
Milyeringa individuals included specialised 
members of the stygofauna ( Stygiocaris sp.) in its 
diet, the aquatic larvae of terrestrial species (caddis 
larvae), and terrestrial species accidentally in the 
water (isopods, ants and cockroaches) (Table 2). 
The identifiable contents were predominantly 
(79%) terrestrial species that had presumably fallen 
into the water and, at the most, only 10% were 
specialised members of the stygofauna. 
Milyeringa on the west coast ate predominantly 
terrestrial isopods ( Buddelundia sp.), while those on 
the east coast fed mainly on cockroaches (Table 3), 
this distribution of prey items differs between 
coasts (G = 16.868, PcO.OOl). Despite these 
differences the source of the food was 
predominantly from outside the water body, of 
terrestrial origin (Table 3). 
Gudgeons examined for prey were larger (F s 1,4 
Table 3 Percentage contribution of prey, by taxa an 
origin, in the guts of Milyeringa veritas on t e 
east and west coasts of the Cape Range 
peninsula (n=34). 
Group 
West 
East 
Insects 
12 
29 
Crustacea 
47 
12 
Aquatic 
12 
9 
Terrestrial 
47 
32 
= 28.75, PcO.OOl) on the west coast (38.5±3.99 mm, 
n=26) than on the east coast (30.6±5.47 mm, n=19), 
as were those (F s 1,31 = 17.5, PcO.OOl) in which 
prey was found (38.6±4.39 mm and 31.2±5.69 mm 
respectively). 
Prey size was converted to common units (body 
length, mm) using empirically derived 
relationships - isopod length (mm) = 2.8 carapace 
width (mm) - 0.04 (r 2 =0.89, P= 0.017); cockroach 
length (mm) = 3.9 head capsule width (mm)+1.5. 
The mean head capsule width of the cockroaches 
was 1.3±0.16 mm (n=8) giving an estimated overall 
body length of 5 mm (by regression). The mean 
carapace width of the isopods was 2.9±1.71 mm 
(n=6) giving an estimated overall length = 8.1 mm 
(by regression). Hence, the bigger west coast fish 
were associated with bigger food items (isopods). 
However, as terrestrial Crustacea generally have 
an energy density only about 70% that of terrestrial 
insects (from Cummins and Wuycheck 1971), then 
the apparent advantage in food size may not confer 
an energetic advantage. 
Associated fauna in the field 
The fish share their habitat with a large number 
of stygofaunal elements, many of which were not 
represented in their gut contents (Table 4). The 
smallest taxa, such as copepods and ostracods, are 
probably outside the size range of prey items, 
which for M. veritas is known to include the length 
range of c. 2.8-14 mm, and for O. candidnm 3 mm 
( Halosbaena ) to an estimated 8 mm (Odonata). No 
fish samples were collected from known remiped 
habitat, although they do occur sympatrically (W.F. 
Humphreys, unpublished 1994). The melitid 
amphipods are sympatric with M. veritas (at 
locations C—24, 25, 105, 274 and 362; W.F. 
Humphreys, unpublished) and abundant in the 
stygal habitat but, despite being within the known 
size range of prey for both species of fish, they are 
not represented in the gut contents. 
