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:
Size:
The carapace (body shell) can grow up to 20 millimeters (0.79 inches) wide.
Shape:
They have a flattened, rounded body, well-suited for hiding in crevices and under rocks.
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).
Claws:
They possess large claws that are easily detachable as a defense mechanism.
Legs:
They have four pairs of walking legs, with the fifth pair being reduced and tucked under the abdomen.
Antennae:
Long antennae are located beside the eyes.
Behavior and Ecology:
Habitat:
They are typically found on rocky substrates in intertidal and shallow subtidal zones.
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.
Defense:
They are known for autotomy, the ability to detach limbs, especially claws, when threatened.
Reef Safe:
They are generally considered reef safe and pose no threat to other inhabitants of a reef aquarium.
Social Behavior:
They often live in pairs or small groups.
In Aquariums:
Tank Setup: They do well in aquariums with plenty of live rock for hiding and feeding.
Water Parameters: Maintain stable water parameters suitable for a marine aquarium.
Feeding: Supplement their filter feeding with meaty foods, such as small pieces of fish or shrimp, and plankton-based foods.
Percnon gibbesi, commonly known as the Sally Lightfoot Crab or Nimble Spray Crab, is a marine crab species characterized by its very flat, thin, and wide carapace (shell). It has a distinctive red to brown coloration, sometimes with fine green marbling, and legs with yellow rings at the joints. Adults can reach a carapace width of about 30 millimeters (1.2 inches). They are known for their agility and speed, especially in their natural rocky habitat.
Physical Characteristics:
Carapace: Flat and thin, with a width of about 30mm.
Coloration: Varies from red to brown, sometimes with green marbling.
Legs: Long and flattened, with yellow rings at the joints.
Spines: Each of the five pairs of walking legs has a row of spines along the leading edge.
Habitat and Behavior:
Percnon gibbesi is native to the Eastern Atlantic, the Mediterranean, and the Canary Islands.
It is considered an invasive species in many parts of the Mediterranean.
It is commonly found in rocky, intertidal and subtidal zones, often hiding under rocks and in crevices.
They are known for their scavenging behavior, feeding on algae, detritus, and small invertebrates.
While generally reef-safe, larger individuals can become aggressive and may prey on small fish and other invertebrates
The Ciliopagurus strigatus, commonly known as the Halloween hermit crab, is a brightly colored hermit crab with a vibrant orange and black striped appearance. They are popular in marine aquariums due to their distinctive colors and usefulness as algae eaters and scavengers.
Key features and characteristics:
Appearance:
The Halloween hermit crab is easily recognizable by its bright orange and red striped "stockings". They also have a small claw on the left side.
Habitat:
They are found in the Central Pacific region, and are often associated with reef environments.
Diet:
They are omnivores, feeding on algae, detritus, leftover food, and sometimes other small creatures.
Behavior:
They are scavengers, sifting through the substrate to clean up detritus and algae. They also help aerate the substrate by moving the sand.
Reef-safe:
Generally considered reef-safe, they do not pose a threat to reef corals or other reef inhabitants.
Shells:
They live in borrowed shells, usually abandoned snail shells, and may even attack and consume snails to obtain a shell.
Maintenance:
In aquariums, they should be provided with a variety of shells to choose from, and their diet may need to be supplemented with algae and other food items if necessary.
In short, the Halloween hermit crab is a visually appealing and useful addition to a marine aquarium, known for its vibrant colors, algae-eating habits, and cleaning skills