200
WILLIAM MACNAE
Periophthalmus chrysospilos tends to be carnivorous but taking
some supplement of plant material. Periophthalmodon schlosseri is
completely carnivorous-in the confined space of a vivarium it has
eaten a specimen of Scartelaos viridis half its own size (Khoo, 1966).
2 . Crustaceans
The crustaceans living in the mangal fall into a few highly
specialized families. Gecarcinids tend t o occur along the landward
fringe but the only one related t o the mangal is Cardisoms carnifex.
The others are more terrestrial and tend to be restricted to oceanic
islands. The family Grapsidae is represented by an assortment of crabs
mostly belonging to the subfamily Sesarminae-they include Clistocoeloma, Cyclograpsus, Ilyograpsus, Helice, Metasesarma, Metopograpsus,
Sarmatium, Sesarma and Utica. Some of these are burrowers, some
wander around seeking shelter where they may, among knee roots of
mangrove trees, under logs, stones, etc. The ocypodid genera associated
with the mangrove include Camptandrium, Cleistostoma, Dotilla,
Dotillopsis, Euplax, Heloecius, Hemiplax, Ilyoplax, Leiopecten, Metaplax, Paracleistostoma, Pseudogelasimus, Tmethypocoelis, Tylodiplax,
Uca and some of the numerous species of Macrophthalmus ; species of
Ocypode may also wander into the mangal. Some representatives of
these genera are found a t similar intertidal levels in cooler waters. Of
xanthids, one of the most conspicuous families of crabs on tropical
shores, only a few representatives have penetrated the mangal. Taxonomic accounts are rarely helpful in locating a species likely to occur
in the mangal, for only occasionally do the taxonomists append any
note about habitat.
Thalassinidean and alpheid prawns burrow in the mud. The mounds
of Thalassina anomala are a conspicuous feature of Asiatic and Australian mangrove forests. Species of Upogebia are widespread in areas
where the ground is firm enough to support a U-shaped burrow.
Species of Alpheus make their labyrinths in wetter areas and are
dominant within certain rhizophora forests.
A single stomatopod, Squilla choprai, has been described from the
mangal of Malaya (Tweedie, 1935a).
All these crustaceans are distributed through the mangal with
reference l~ several variables of which the most important concern the
nature of the substratum-its particle size and degree of consolidation,
humidity, saltness of the ground water, and t o a lesser extent temperature but then only towards the northern and southern limits.
Very few of the crabs listed above, apart from Cardisoma and some
species of Sesarma, reach a large size. None has any great importance
WILLIAM MACNAE
Periophthalmus chrysospilos tends to be carnivorous but taking
some supplement of plant material. Periophthalmodon schlosseri is
completely carnivorous-in the confined space of a vivarium it has
eaten a specimen of Scartelaos viridis half its own size (Khoo, 1966).
2 . Crustaceans
The crustaceans living in the mangal fall into a few highly
specialized families. Gecarcinids tend t o occur along the landward
fringe but the only one related t o the mangal is Cardisoms carnifex.
The others are more terrestrial and tend to be restricted to oceanic
islands. The family Grapsidae is represented by an assortment of crabs
mostly belonging to the subfamily Sesarminae-they include Clistocoeloma, Cyclograpsus, Ilyograpsus, Helice, Metasesarma, Metopograpsus,
Sarmatium, Sesarma and Utica. Some of these are burrowers, some
wander around seeking shelter where they may, among knee roots of
mangrove trees, under logs, stones, etc. The ocypodid genera associated
with the mangrove include Camptandrium, Cleistostoma, Dotilla,
Dotillopsis, Euplax, Heloecius, Hemiplax, Ilyoplax, Leiopecten, Metaplax, Paracleistostoma, Pseudogelasimus, Tmethypocoelis, Tylodiplax,
Uca and some of the numerous species of Macrophthalmus ; species of
Ocypode may also wander into the mangal. Some representatives of
these genera are found a t similar intertidal levels in cooler waters. Of
xanthids, one of the most conspicuous families of crabs on tropical
shores, only a few representatives have penetrated the mangal. Taxonomic accounts are rarely helpful in locating a species likely to occur
in the mangal, for only occasionally do the taxonomists append any
note about habitat.
Thalassinidean and alpheid prawns burrow in the mud. The mounds
of Thalassina anomala are a conspicuous feature of Asiatic and Australian mangrove forests. Species of Upogebia are widespread in areas
where the ground is firm enough to support a U-shaped burrow.
Species of Alpheus make their labyrinths in wetter areas and are
dominant within certain rhizophora forests.
A single stomatopod, Squilla choprai, has been described from the
mangal of Malaya (Tweedie, 1935a).
All these crustaceans are distributed through the mangal with
reference l~ several variables of which the most important concern the
nature of the substratum-its particle size and degree of consolidation,
humidity, saltness of the ground water, and t o a lesser extent temperature but then only towards the northern and southern limits.
Very few of the crabs listed above, apart from Cardisoma and some
species of Sesarma, reach a large size. None has any great importance