216
WILLIAM MACNAE
than 200 mm, the average for females being around 160 mm, for males
slightly less. I n Ceylon the average size seen on market stalls was
around 50-60 mm-this was probably the result of over-collecting. I n
Australia, Stephenson and Campbell ( 1960) record females reaching
165 mm and males 195 mm. SerBne’s (1952) specimens from Viet Nam
range from about 60 to 95 mm.
Arriola (1940) has given an account of moulting and growth from
6 x 9 mm up to 90 x 130 mm in twelve moults a t intervals increasing
from 9 days for the first two stadia observed up to 23 days for the last
stadium observed. The total period for which they were kept and
studied was 5 months. This suggests that under Philippine conditions
growth is rapid. Mating, according to Arriola, takes place just after
moulting while both individuals are still soft. (De Breitas (unpublished
data), who has been observing captive Penaeus indicus in Lourenyo
Marques, has noted that in this species too, mating occurs just after
moulting between a hard male and a soft female.) Eggs are carried
around (Jide Arriola) for 17 days and hatch as zoeae. Arriola was
unable to rear the larvae and no records of the duration of the
planktonic period exist.
Arriola records that young crabs enter the estuaries around Manila
Bay between June and August in large numbers and suggests that
maturity may be reached within a year. Females may migrate t o
spawn their larvae or they may shed them on an ebbing tide. The
widespread distribution suggests a long pelagic larval period.
Crosnier (1962) records the finding of several specimens almost
undigested in the stomach of a specimen of the tiger shark (Galeocerdo
cuvieri Agassiz) in the Mogambique Channel about 20 km from the edge
of the continental shelf and 50 km from the Madagascar coast. He
comes to the conclusion that these crabs also live at the edge of the
continental shelf since the freshness of the specimens in the shark’s
stomach precluded their having been caught inshore.
I n shore at Inhaca Xcylla has a wide range of habitats. Local Ronga
fishermen have told me that the largest specimens, almost always
female, are collected from burrows exposed by equinoctial tides along
the channels between the sandbanks. They suggest that the crabs
migrate downwards as they grow; smaller specimens are caught far
up the creeks within the mangrove and larger ones as the creeks
approach the sea and the mangrove edge. Specimens taken within the
mangrove are always dark in colour, usually a dark mottled green,
specimens from the channels a t Inhaca are usually brownish rather than
greenish. It would seem that, like most other portunids these crabs are
capable of some degree of colour change related to the environment.
WILLIAM MACNAE
than 200 mm, the average for females being around 160 mm, for males
slightly less. I n Ceylon the average size seen on market stalls was
around 50-60 mm-this was probably the result of over-collecting. I n
Australia, Stephenson and Campbell ( 1960) record females reaching
165 mm and males 195 mm. SerBne’s (1952) specimens from Viet Nam
range from about 60 to 95 mm.
Arriola (1940) has given an account of moulting and growth from
6 x 9 mm up to 90 x 130 mm in twelve moults a t intervals increasing
from 9 days for the first two stadia observed up to 23 days for the last
stadium observed. The total period for which they were kept and
studied was 5 months. This suggests that under Philippine conditions
growth is rapid. Mating, according to Arriola, takes place just after
moulting while both individuals are still soft. (De Breitas (unpublished
data), who has been observing captive Penaeus indicus in Lourenyo
Marques, has noted that in this species too, mating occurs just after
moulting between a hard male and a soft female.) Eggs are carried
around (Jide Arriola) for 17 days and hatch as zoeae. Arriola was
unable to rear the larvae and no records of the duration of the
planktonic period exist.
Arriola records that young crabs enter the estuaries around Manila
Bay between June and August in large numbers and suggests that
maturity may be reached within a year. Females may migrate t o
spawn their larvae or they may shed them on an ebbing tide. The
widespread distribution suggests a long pelagic larval period.
Crosnier (1962) records the finding of several specimens almost
undigested in the stomach of a specimen of the tiger shark (Galeocerdo
cuvieri Agassiz) in the Mogambique Channel about 20 km from the edge
of the continental shelf and 50 km from the Madagascar coast. He
comes to the conclusion that these crabs also live at the edge of the
continental shelf since the freshness of the specimens in the shark’s
stomach precluded their having been caught inshore.
I n shore at Inhaca Xcylla has a wide range of habitats. Local Ronga
fishermen have told me that the largest specimens, almost always
female, are collected from burrows exposed by equinoctial tides along
the channels between the sandbanks. They suggest that the crabs
migrate downwards as they grow; smaller specimens are caught far
up the creeks within the mangrove and larger ones as the creeks
approach the sea and the mangrove edge. Specimens taken within the
mangrove are always dark in colour, usually a dark mottled green,
specimens from the channels a t Inhaca are usually brownish rather than
greenish. It would seem that, like most other portunids these crabs are
capable of some degree of colour change related to the environment.