FAUNA AND FLORA OF MANGROVE SWAMPS
151
The lists of birds and mammals given below, are the result of my
own sight records supplemented by records given in various taxonomic
books on the birds and mammals of the regions concerned.
A few studies of the insects affecting such crops as coconuts,
mangoes, cloves and cashew nuts grown in the maritime regions round
the Indian Ocean give hints as to which insects might be expected in
the mangrove areas nearby. The accounts given by Vanderplank (1960)
and by Way (1954a,b) of the ecology of the tailor ant, Oecophylla sp.,
probably apply to the colonies of these ants on various mangrove trees
(see Fig. 57).
( 2 ) The presence of rot holes in the branches, and collections of
water in the clefts between branches and trunks provide a near freshwater environment for developing insects and are of medical importance
in relation to mosquito carriers of viraemias, filariases and to a lesser
extent malaria.
(3) The surface of the soil constitutes an environment which is now
submerged and now emergent and sub-aerial. The surface layers of
the soil and the small collection of sodden litter above it have interstices which are now water-filled and now air-filled. The animals living
there must be tolerant of both sets of conditions or have developed
behavioural patterns which enable them to survive. For example, as
the tide rises certain crabs and ants close their burrows with a plug of
soil and remain in a bubble of air while the tidal water covers the soil.
Compared with a completely terrestrial forest there is little or no
litter. Dead leaves are dropped at all seasons and only in the landward
fringe do they tend to collect, there t o provide shelter for many species
of tiny gastropods-species of Melampus, of Xyncera (= Assiminea),
and of various other genera. Elsewhere the leaves are devoured soon
after they fall. I have often seen specimens of Sesarma scrambling after
and squabbling over a fallen leaf which is finally dragged to a burrow
and eaten in the doorway.
(4) Animals may live in the soil and by their activities modify it.
(5) Permanent and semi-permanent pools may provide an environment at a topographically higher level for animals which would
normally be found only in the water courses of the mangal or a t the
seaward fringe.
It is only the last three of these categories that I have studied
personally, and then primarily to establish what crabs and molluscs
are there, their habits, zonation and distribution. Few attempts have
been made to find out how any individual species arrives in its chosen
environment, and once there, how it succeeds in coping with these
types of environment.
A.iK.B.-6
6
151
The lists of birds and mammals given below, are the result of my
own sight records supplemented by records given in various taxonomic
books on the birds and mammals of the regions concerned.
A few studies of the insects affecting such crops as coconuts,
mangoes, cloves and cashew nuts grown in the maritime regions round
the Indian Ocean give hints as to which insects might be expected in
the mangrove areas nearby. The accounts given by Vanderplank (1960)
and by Way (1954a,b) of the ecology of the tailor ant, Oecophylla sp.,
probably apply to the colonies of these ants on various mangrove trees
(see Fig. 57).
( 2 ) The presence of rot holes in the branches, and collections of
water in the clefts between branches and trunks provide a near freshwater environment for developing insects and are of medical importance
in relation to mosquito carriers of viraemias, filariases and to a lesser
extent malaria.
(3) The surface of the soil constitutes an environment which is now
submerged and now emergent and sub-aerial. The surface layers of
the soil and the small collection of sodden litter above it have interstices which are now water-filled and now air-filled. The animals living
there must be tolerant of both sets of conditions or have developed
behavioural patterns which enable them to survive. For example, as
the tide rises certain crabs and ants close their burrows with a plug of
soil and remain in a bubble of air while the tidal water covers the soil.
Compared with a completely terrestrial forest there is little or no
litter. Dead leaves are dropped at all seasons and only in the landward
fringe do they tend to collect, there t o provide shelter for many species
of tiny gastropods-species of Melampus, of Xyncera (= Assiminea),
and of various other genera. Elsewhere the leaves are devoured soon
after they fall. I have often seen specimens of Sesarma scrambling after
and squabbling over a fallen leaf which is finally dragged to a burrow
and eaten in the doorway.
(4) Animals may live in the soil and by their activities modify it.
(5) Permanent and semi-permanent pools may provide an environment at a topographically higher level for animals which would
normally be found only in the water courses of the mangal or a t the
seaward fringe.
It is only the last three of these categories that I have studied
personally, and then primarily to establish what crabs and molluscs
are there, their habits, zonation and distribution. Few attempts have
been made to find out how any individual species arrives in its chosen
environment, and once there, how it succeeds in coping with these
types of environment.
A.iK.B.-6
6