GRAPSUS ALBOLINEATUS - (LATREILLE, IN MILBERT, 1812)
Arthropoda (Phylum) > Crustacea (Subphylum) > Malacostraca (Class) > Eumalacostraca (Subclass) > Eucarida (Superorder) > Decapoda (Order) > Pleocyemata (Suborder) > Brachyura (Infraorder) > Eubrachyura (Section) > Thoracotremata (Subsection) > Grapsoidea (Superfamily) > Grapsidae (Family) > Grapsus (Genus)
Mottled crab, Mottled lightfoot crab, Mottled Sally-light-foot, Sally-light-foot crab
Synonymes
Cancer strigosus (Herbst, 1799)
Grapsus (Goniopsis) flavipes (MacLeay, 1838)
Grapsus albolineatus (Lamarck, 1818)
Grapsus longipes (Stimpson, 1858)
Grapsus peroni (H. Milne Edwards, 1853)
Grapsus strigosus (Herbst, 1799)
-----------------------------------------------
Description
Body width 5-6cm. Body circular flat, dark with a pattern of light spots in bands at the lower portion of the body. Pincers very short flattened. Very long walking legs tipped with pointy claws. With these legs, the crab clings tightly so it doesn't get washed away in the waves, and can scramble quickly among slippery rocks. Colours seen range from reddish to bluish and greenish. 'Alba' means 'white' and 'lineatus' means lines. The body indeed has fine white lines. Males have larger pincers than the females. Colouration - Dark green: Carapace ; Mottled brown: Legs
Distribution
Chisimaio, Gesira, Mogadishu, New Caledonian Exclusive Economic Zone, Red Sea, Sar Uanle , Somalia, Tanzania, West Indian Ocean
Similar species
Plagusia squamosa (Herbst, 1790) which has a more squarish less flat more bumpy body.
Grapsus grapsus (Linnaeus, 1758)
Grapsus adscensionis (Osbeck, 1765)
Grapsus tenuicrustatus (Herbst, 1783)
Guinusia chabrus (Linnaeus, 1758)
Biotope
This colourful and swift crab is sometimes seen on our some of our rocky shores. Small groups may clamber noisily among rocks on seawalls or natural rocks. Sometimes, it may also be seen on the reef flats near the rocky shore. It is more active at night and seldom seen during daylight. Very shy, it disappears instantly into crevices at the slightest sign of danger. Or it may flatten against the encrusted rocks, where it blends in with this surroundings.
Alimentation
The tropical rocky shore crab Grapsus albolineatus feeds primarily on filamentous algae but eats animal matter whenever it is available. During the summer the crab's diet switches to encrusting algae due to a die-off of filamentous algae. As a result of the switch the nutrients in the diet of the crab vary seasonally and may influence the fitness of the crab. Maintenance, growth, reproductive performance and nutrient storage of crabs were examined under four dietary regimes of increasing nutritional value ranging from low organic to high protein content. The nutritional quality of these diets significantly affected crab survival and moulting. Crabs fed on the nutritionally superior diet of algae and meat exhibited enhanced growth, higher levels of energy in the reproductive organs and stored more energy in the hepatopancreas than did individuals on the shore and crabs fed only on algal diets in the laboratory. Filamentous algae were a better food source than other algae, resulting in fewer deaths and superior levels of maintenance and growth. Growth and maintenance can occur on a pure algal diet, but reproductive performance and nutrient storage require some degree of added nutrients in the form of animal matter in the diet. Crabs fed coralline or foliose algae had higher mortality and fewer successful moults than crabs fed the other two diets. The fitness of G. albolineatus appears to be limited by the amount of extra nutrients obtained from animal matter. The opportunistic consumption of animal material in the form of carrion, or of animals associated with dietary algae, could be a key factor in the reproductive success of this crab.
Mottled crab, Mottled lightfoot crab, Mottled Sally-light-foot, Sally-light-foot crab
Synonymes
Cancer strigosus (Herbst, 1799)
Grapsus (Goniopsis) flavipes (MacLeay, 1838)
Grapsus albolineatus (Lamarck, 1818)
Grapsus longipes (Stimpson, 1858)
Grapsus peroni (H. Milne Edwards, 1853)
Grapsus strigosus (Herbst, 1799)
-----------------------------------------------
Description
Body width 5-6cm. Body circular flat, dark with a pattern of light spots in bands at the lower portion of the body. Pincers very short flattened. Very long walking legs tipped with pointy claws. With these legs, the crab clings tightly so it doesn't get washed away in the waves, and can scramble quickly among slippery rocks. Colours seen range from reddish to bluish and greenish. 'Alba' means 'white' and 'lineatus' means lines. The body indeed has fine white lines. Males have larger pincers than the females. Colouration - Dark green: Carapace ; Mottled brown: Legs
Distribution
Chisimaio, Gesira, Mogadishu, New Caledonian Exclusive Economic Zone, Red Sea, Sar Uanle , Somalia, Tanzania, West Indian Ocean
Similar species
Plagusia squamosa (Herbst, 1790) which has a more squarish less flat more bumpy body.
Grapsus grapsus (Linnaeus, 1758)
Grapsus adscensionis (Osbeck, 1765)
Grapsus tenuicrustatus (Herbst, 1783)
Guinusia chabrus (Linnaeus, 1758)
Biotope
This colourful and swift crab is sometimes seen on our some of our rocky shores. Small groups may clamber noisily among rocks on seawalls or natural rocks. Sometimes, it may also be seen on the reef flats near the rocky shore. It is more active at night and seldom seen during daylight. Very shy, it disappears instantly into crevices at the slightest sign of danger. Or it may flatten against the encrusted rocks, where it blends in with this surroundings.
Alimentation
The tropical rocky shore crab Grapsus albolineatus feeds primarily on filamentous algae but eats animal matter whenever it is available. During the summer the crab's diet switches to encrusting algae due to a die-off of filamentous algae. As a result of the switch the nutrients in the diet of the crab vary seasonally and may influence the fitness of the crab. Maintenance, growth, reproductive performance and nutrient storage of crabs were examined under four dietary regimes of increasing nutritional value ranging from low organic to high protein content. The nutritional quality of these diets significantly affected crab survival and moulting. Crabs fed on the nutritionally superior diet of algae and meat exhibited enhanced growth, higher levels of energy in the reproductive organs and stored more energy in the hepatopancreas than did individuals on the shore and crabs fed only on algal diets in the laboratory. Filamentous algae were a better food source than other algae, resulting in fewer deaths and superior levels of maintenance and growth. Growth and maintenance can occur on a pure algal diet, but reproductive performance and nutrient storage require some degree of added nutrients in the form of animal matter in the diet. Crabs fed coralline or foliose algae had higher mortality and fewer successful moults than crabs fed the other two diets. The fitness of G. albolineatus appears to be limited by the amount of extra nutrients obtained from animal matter. The opportunistic consumption of animal material in the form of carrion, or of animals associated with dietary algae, could be a key factor in the reproductive success of this crab.