Description
The "Purple Porcelain Crab," Petrolisthes sp., is a small, flat-bodied crab with a distinctive coloration, known for its vibrant purple hues and the ability to detach its claws when threatened. These crabs are found in tropical oceans and are popular additions to reef aquariums due to their peaceful nature and reef-safe qualities.
Physical Characteristics:
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Size:
The carapace (body shell) can grow up to 20 millimeters (0.79 inches) wide.
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Shape:
They have a flattened, rounded body, well-suited for hiding in crevices and under rocks.
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Coloration:
While often reddish-brown or blueish-grey, they are known for their vibrant purple claws and markings on the body. The claws (chelipeds) are disproportionately large and may have a blueish hue, particularly at the joints (knuckles).
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Claws:
They possess large claws that are easily detachable as a defense mechanism.
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Legs:
They have four pairs of walking legs, with the fifth pair being reduced and tucked under the abdomen.
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Antennae:
Long antennae are located beside the eyes.
Behavior and Ecology:
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Habitat:
They are typically found on rocky substrates in intertidal and shallow subtidal zones.
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Feeding:
Petrolisthes sp. are filter feeders, using specialized limbs near their mouths to capture plankton and other small particles from the water. They may also scavenge for food and are known to feed on "marine snow" and micro-invertebrates.
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Defense:
They are known for autotomy, the ability to detach limbs, especially claws, when threatened.
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Reef Safe:
They are generally considered reef safe and pose no threat to other inhabitants of a reef aquarium.
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Social Behavior:
They often live in pairs or small groups.
In Aquariums:
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Tank Setup: They do well in aquariums with plenty of live rock for hiding and feeding.
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Water Parameters: Maintain stable water parameters suitable for a marine aquarium.
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Feeding: Supplement their filter feeding with meaty foods, such as small pieces of fish or shrimp, and plankton-based foods.