FAUNA AND FLORA OF MANGROVE SWAMPS
177
55FF) and Syncera brevicula (Yfr.) f. miniata which may be abundant.
Where soft mud occurs Telescopium telescopium L. (Fig. 56G) and T.
mauritsi Butot are common. Species of Cerithidea, mostly decollate
forms, are common and these climb up and shelter in clumps on the
bases of the trunks of the trees : C. decollata (L.) (Fig. 55K) is abundant
on the African coast, C. alata, C. djadjariensis (K. Mart), C. cingulata
(Gm.), C. obtusa, C. qundrata Sow. and C. weyersi Dautzenberg all occur
in South East Asia and C. anticipata Iredale in Australia. Where
several species occur there is probably some degree of zonation.
It was most surprising to find a saccoglossan nudibranch Elysia sp.
living in pools of reduced salinity in the forest of Bruguiera cylindrica
near Kuala Selangor in Malaya during December 1966 and January
1967. Swimming in the same pools were tadpoles, presumably of
Rana cancrivora. A second species of Elysia was common in pools
among cultivated Ceriops tagal near Chonburi a few kilometres south
of Bangkok.
3. Rhixophora forests
In mature forests of R. mucronata where the soil is well compacted
one finds a fauna similar to that of the bruguiera forests. I n mature
forests of R. apiculata the fauna shows stronger affinities with that of
the landward fringe.
I n forests of R. mucronata or R. stylosa growing behind a seaward
fringe on soil in an unconsolidated state the fauna is restricted to
alpheid prawns, the snapping of which reveals their presence, and
to species of the crab genus Nacrophthalmus. The bright blue crab
Metopograpsus latifrons (White) runs round on the prop roots of the
trees and scavenges amongst the debris collected among the mass of
interweaving roots. This crab is mainly Indo-Australian but has
recently (Macnae, unpublished data) been found in the mangroves of
northern Mopambique.
Of large snails, Telescopiuna telescopium will be the only one present
for it alone can gain support on the mud.
4. The seaward fringes and channel banks
These two will be considered together for they have much in
common. I n many areas on the western coasts of the Malayan peninsula, both in Thailand and in Malaya, and in many places in the great
estuaries of Borneo they differ only in extent. The seaward slopes tend
to be more gentle and the channelward slopes are steeper but this
merely condenses the fauna.
The fauna will depend on many factors affecting the substratum:
some of these depend on the degree of consolidation of the soil ; others
177
55FF) and Syncera brevicula (Yfr.) f. miniata which may be abundant.
Where soft mud occurs Telescopium telescopium L. (Fig. 56G) and T.
mauritsi Butot are common. Species of Cerithidea, mostly decollate
forms, are common and these climb up and shelter in clumps on the
bases of the trunks of the trees : C. decollata (L.) (Fig. 55K) is abundant
on the African coast, C. alata, C. djadjariensis (K. Mart), C. cingulata
(Gm.), C. obtusa, C. qundrata Sow. and C. weyersi Dautzenberg all occur
in South East Asia and C. anticipata Iredale in Australia. Where
several species occur there is probably some degree of zonation.
It was most surprising to find a saccoglossan nudibranch Elysia sp.
living in pools of reduced salinity in the forest of Bruguiera cylindrica
near Kuala Selangor in Malaya during December 1966 and January
1967. Swimming in the same pools were tadpoles, presumably of
Rana cancrivora. A second species of Elysia was common in pools
among cultivated Ceriops tagal near Chonburi a few kilometres south
of Bangkok.
3. Rhixophora forests
In mature forests of R. mucronata where the soil is well compacted
one finds a fauna similar to that of the bruguiera forests. I n mature
forests of R. apiculata the fauna shows stronger affinities with that of
the landward fringe.
I n forests of R. mucronata or R. stylosa growing behind a seaward
fringe on soil in an unconsolidated state the fauna is restricted to
alpheid prawns, the snapping of which reveals their presence, and
to species of the crab genus Nacrophthalmus. The bright blue crab
Metopograpsus latifrons (White) runs round on the prop roots of the
trees and scavenges amongst the debris collected among the mass of
interweaving roots. This crab is mainly Indo-Australian but has
recently (Macnae, unpublished data) been found in the mangroves of
northern Mopambique.
Of large snails, Telescopiuna telescopium will be the only one present
for it alone can gain support on the mud.
4. The seaward fringes and channel banks
These two will be considered together for they have much in
common. I n many areas on the western coasts of the Malayan peninsula, both in Thailand and in Malaya, and in many places in the great
estuaries of Borneo they differ only in extent. The seaward slopes tend
to be more gentle and the channelward slopes are steeper but this
merely condenses the fauna.
The fauna will depend on many factors affecting the substratum:
some of these depend on the degree of consolidation of the soil ; others