FAUNA AND FLORA O F MANGROVE SWAMPS
185
the burrows. Rhythmic activity centred on the progression of the
tides is aIso important and much of this is as yet ill understood.
Rhythms of this sort have been much studied in the laboratory (see
the work of Fingerman, Vernberg, F. A. Brown Jr. and others), but
little of it has been applied in the field and no work has been done
on these aspects in relation to Indo-west-Pacific forms.
1. Mud-skippers
Mud-skippers are gobioid fishes highly characteristic of the mangal
and/or its immediate vicinity. They comprise Boleophthalmus boddaerti
(Fig. 66), Xcartelaos viridis (Fig. 76), Periophthalmodon schlosseri (Fig.
63) and species of Periophthalmus.
Harms (1929) described ecological differences between species of
Periophthalmus, and Eggert (1929a, 1935) sought for and recognized
morphological differences between these species. Periophthalmus
chrysospilos (Figs. 59 and 60) and other species with fused pelvic fins
are shown by these authors to be characteristic of the seaward fringes
of the mangal. A second series of often sympatric species with partially
fused pelvic fins are characteristic of higher levels. Members of both
groups are difficult to distinguish from one another, and a revision
which takes into account not only morphological features but also
ecological preferences and behavioural patterns is necessary.
The group with fused pelvics is relatively uniform and may well be
a polytypic species with quite well-defined varieties. The other group
is much more puzzling. Herre (1941) states in relation to it that “this
polymorphic species has been divided by Eggert into many species
most of which are merely ill-defined varieties, but a few are valid ”which! He makes no mention. Whitley (1953) states that P. argentilineatw C. & V., P. vulgaris Eggert and P. koelreuteri Pallas are all to
be included in one species, which he identifies as P. kalolo Lesson. This
is the earliest name available, since he considers that P. koelreuteri,
although earlier in fact, is probably not conspecific for it was described
from West African coasts.
P. kalolo has been recorded by McCulloch and Ogilby (1919) from
rock-strewn shores in the New Hebrides and Polynesia. This habitat
Harms and Eggert considered to be typical for P . harmsi Eggert, a
species which is probably identical with P. kalolo. One suspects that
these were wandering, immature and sexually inactive individuals, for
none of the authors who describe finding mud-skippers on open rockstrewn shores give any indication that the fishes found there were
occupying permanent ‘‘ homes ”. My own observations in the Bako
National Park in Sarawak confirm that specimens collected on a rocky
185
the burrows. Rhythmic activity centred on the progression of the
tides is aIso important and much of this is as yet ill understood.
Rhythms of this sort have been much studied in the laboratory (see
the work of Fingerman, Vernberg, F. A. Brown Jr. and others), but
little of it has been applied in the field and no work has been done
on these aspects in relation to Indo-west-Pacific forms.
1. Mud-skippers
Mud-skippers are gobioid fishes highly characteristic of the mangal
and/or its immediate vicinity. They comprise Boleophthalmus boddaerti
(Fig. 66), Xcartelaos viridis (Fig. 76), Periophthalmodon schlosseri (Fig.
63) and species of Periophthalmus.
Harms (1929) described ecological differences between species of
Periophthalmus, and Eggert (1929a, 1935) sought for and recognized
morphological differences between these species. Periophthalmus
chrysospilos (Figs. 59 and 60) and other species with fused pelvic fins
are shown by these authors to be characteristic of the seaward fringes
of the mangal. A second series of often sympatric species with partially
fused pelvic fins are characteristic of higher levels. Members of both
groups are difficult to distinguish from one another, and a revision
which takes into account not only morphological features but also
ecological preferences and behavioural patterns is necessary.
The group with fused pelvics is relatively uniform and may well be
a polytypic species with quite well-defined varieties. The other group
is much more puzzling. Herre (1941) states in relation to it that “this
polymorphic species has been divided by Eggert into many species
most of which are merely ill-defined varieties, but a few are valid ”which! He makes no mention. Whitley (1953) states that P. argentilineatw C. & V., P. vulgaris Eggert and P. koelreuteri Pallas are all to
be included in one species, which he identifies as P. kalolo Lesson. This
is the earliest name available, since he considers that P. koelreuteri,
although earlier in fact, is probably not conspecific for it was described
from West African coasts.
P. kalolo has been recorded by McCulloch and Ogilby (1919) from
rock-strewn shores in the New Hebrides and Polynesia. This habitat
Harms and Eggert considered to be typical for P . harmsi Eggert, a
species which is probably identical with P. kalolo. One suspects that
these were wandering, immature and sexually inactive individuals, for
none of the authors who describe finding mud-skippers on open rockstrewn shores give any indication that the fishes found there were
occupying permanent ‘‘ homes ”. My own observations in the Bako
National Park in Sarawak confirm that specimens collected on a rocky