pustular structures and elongate pellet-roofed tunnel workings appearing on the tidal flat surface. Dense tunnel workings may coalesce to form extensive mats of pellet-roofed
tunnels over the tidal flat resembling “pustular mats.”
Soldier crabs function ecologically as major
bioturbators and aerators of sediment in the intertidal ecosystem and as food items both for avifauna at low tide and
for nekton on the high tide. Their daily ingestion of the
substrate and cycling of groundwater in conjunction with
a physiological tendency to accumulate heavy metals suggests that they can act as bioindicators of pollution events.
They have an effect on meiofauna assemblages and nutrient fluxes within the substrate over an area that may be
kilometers in extent, depending on the scale of the habitat.
Soldier crabs recorded in estuaries
Soldier crabs have been documented in estuaries throughout their Indo-west Pacific biogeographic range and studied in regard to various aspects of their ecology including
activity patterns, physiology, burrowing behavior,
swarming behavior, feeding behavior, reproductive
behavior, population dynamics, benthic metabolism, and
the effect of soldier crab feeding on sediment and
meiofauna (Cameron, 1966; Kelemec 1979; Farrelly and
Greenaway, 1987; Maitland and Maitland, 1992; Dittman,
1993; Shih, 1995; Dittman, 1998; Rossi and Chapman,
2003; Sadao, 2003; Webb and Eyre, 2004; Takeda,
2005). The importance of soldier crabs in estuaries has
been recognized for their role as burrowing organisms in
rapidly reworking sandy substrates and effecting oxygenation, nitrogen fluxes, and other chemical changes. They
effect sediment turnover and sediment structuring to
a depth generally of 10–15 cm (Unno and Semeniuk,
2008), though they can occur to a depth of 30 cm.
River mouths are often locations for major towns or cities, and consequently researchers are located close to their
study sites. In Japan and Southeast Asia, mountainous terrain and monsoonal climate result in short rivers draining
to the coast and developing estuaries. Most estuaries are of
the ria, coastal plain (flooded valley), or deltaic estuarine
types and are bordered by dense stands of mangroves
(Fairbridge, 1980). For instance, M. guinotae has been
studied on shore-parallel platform tidal flats adjacent to
mangroves in the Nadasa River estuary on Iriomote-jima,
Japan, and, similarly, Shih (1995) observed
M. brevidactylus on sandy tidal flats bordering mangrove
woodlands in the Tanshui River estuary in Taiwan.
Soldier Crabs (Mictyridae), Table 1 (Continued )
Species
Biogeographic range
General features
Image
Mictyris
thailandensis Davie,
Wisespongpand &
Shih, 2013
West coast of Thailand: Andaman coast
between Ranong Province and Pakbara Beach,
Satun Province
Typical size: 15 mm
Eyes: medium
Color: light blue, with pale blue to cream
sides; white chelipeds and fawn walking
legs (Photo: Puntip Wisespongpand)
Soldier Crabs (Mictyridae), Figure 1 Map of coastal central Asia
and Southeast Asia and Australia showing the distribution of the
eight species of Mictyris.
SOLDIER CRABS (MICTYRIDAE)
609
tunnels over the tidal flat resembling “pustular mats.”
Soldier crabs function ecologically as major
bioturbators and aerators of sediment in the intertidal ecosystem and as food items both for avifauna at low tide and
for nekton on the high tide. Their daily ingestion of the
substrate and cycling of groundwater in conjunction with
a physiological tendency to accumulate heavy metals suggests that they can act as bioindicators of pollution events.
They have an effect on meiofauna assemblages and nutrient fluxes within the substrate over an area that may be
kilometers in extent, depending on the scale of the habitat.
Soldier crabs recorded in estuaries
Soldier crabs have been documented in estuaries throughout their Indo-west Pacific biogeographic range and studied in regard to various aspects of their ecology including
activity patterns, physiology, burrowing behavior,
swarming behavior, feeding behavior, reproductive
behavior, population dynamics, benthic metabolism, and
the effect of soldier crab feeding on sediment and
meiofauna (Cameron, 1966; Kelemec 1979; Farrelly and
Greenaway, 1987; Maitland and Maitland, 1992; Dittman,
1993; Shih, 1995; Dittman, 1998; Rossi and Chapman,
2003; Sadao, 2003; Webb and Eyre, 2004; Takeda,
2005). The importance of soldier crabs in estuaries has
been recognized for their role as burrowing organisms in
rapidly reworking sandy substrates and effecting oxygenation, nitrogen fluxes, and other chemical changes. They
effect sediment turnover and sediment structuring to
a depth generally of 10–15 cm (Unno and Semeniuk,
2008), though they can occur to a depth of 30 cm.
River mouths are often locations for major towns or cities, and consequently researchers are located close to their
study sites. In Japan and Southeast Asia, mountainous terrain and monsoonal climate result in short rivers draining
to the coast and developing estuaries. Most estuaries are of
the ria, coastal plain (flooded valley), or deltaic estuarine
types and are bordered by dense stands of mangroves
(Fairbridge, 1980). For instance, M. guinotae has been
studied on shore-parallel platform tidal flats adjacent to
mangroves in the Nadasa River estuary on Iriomote-jima,
Japan, and, similarly, Shih (1995) observed
M. brevidactylus on sandy tidal flats bordering mangrove
woodlands in the Tanshui River estuary in Taiwan.
Soldier Crabs (Mictyridae), Table 1 (Continued )
Species
Biogeographic range
General features
Image
Mictyris
thailandensis Davie,
Wisespongpand &
Shih, 2013
West coast of Thailand: Andaman coast
between Ranong Province and Pakbara Beach,
Satun Province
Typical size: 15 mm
Eyes: medium
Color: light blue, with pale blue to cream
sides; white chelipeds and fawn walking
legs (Photo: Puntip Wisespongpand)
Soldier Crabs (Mictyridae), Figure 1 Map of coastal central Asia
and Southeast Asia and Australia showing the distribution of the
eight species of Mictyris.
SOLDIER CRABS (MICTYRIDAE)
609