Ghost crabs are a fascinating species found along sandy beaches worldwide. Their pale, translucent bodies allow them to camouflage seamlessly against the sand, making them elusive to spot. While many people enjoy observing these quirky crabs scuttling across the shoreline their eating habits remain a mystery to most. In this article we’ll uncover everything you need to know about the ghost crab’s diet and feeding behaviors.
An Overview of Ghost Crab Diet
Ghost crabs are omnivorous opportunistic feeders, meaning they will eat both plant and animal matter depending on availability. Their diet consists of
- Insects and insect larvae
- Mole crabs
- Clams
- Small crustaceans
- Turtle eggs and hatchlings
- Rotting vegetation and detritus
- Anything else they can scavenge along the beach
Rather than hunting, ghost crabs mostly scavenge for already dead or decaying organisms to eat. They use their powerful claws and legs to dig through sand in search of food. Their senses of smell and touch allow them to detect prey buried in the substrate.
Ghost crabs are nocturnal, emerging from their sandy burrows at night to feed. This helps them avoid overheating in the hot sun and avoid predators that are active during the day. Under the cover of darkness, they forage along the swash zone, where waves wash ashore potential sources of food.
Hunting and Foraging Behaviors
While ghost crabs are adept scavengers, they do occasionally hunt for live prey as well. They may chase down small crustaceans trying to escape an incoming wave or dig up unsuspecting mole crabs buried in the sand.
One unique hunting technique ghost crabs utilize is to locate female sea turtles laying eggs on the beach at night. The crabs then dig up the eggs and eat them before they have a chance to hatch. They also prey on newly hatched turtle hatchlings attempting to make their way to the sea.
Ghost crabs use their claws and legs in different ways while foraging:
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The large, unequally sized claws are used to dig, capture and shred food.
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The walking legs have sensitive hairs that detect chemicals from potential food sources, guiding the crab toward tasty morsels buried in the sand.
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Shorter fifth legs are used to push sand behind the crab as it burrows. This also uncovers potential meals.
The crabs’ ability to dig quickly and efficiently through the sand gives them an advantage when searching for food along the beach.
Preferred Foods
Ghost crabs are opportunistic feeders, but there are some foods they prefer when available:
Mole crabs: A burrowing crab species that ghost crabs actively dig up and consume. Their soft bodies provide lots of nutrients.
Turtle eggs: Sea turtle eggs are a prized high-protein meal. Ghost crabs seek out turtle nests and dig up the eggs before they can hatch.
Insects: Beetles, flies, ants, grubs and other insects are a convenient food source ghost crabs can easily capture and eat.
Clams: Ghost crabs pry open clam shells using their claws and eat the meat inside.
Fish carcasses: When fish wash ashore, ghost crabs scavenge the remains. Rotting flesh provides essential nutrients.
Vegetation: Decaying seaweed and marsh grass provides carbohydrates.
Targeting turtle eggs and mole crabs does involve some hunting effort, but most of these foods are simply scavenged opportunistically by ghost crabs patrolling the beaches at night.
Digestion and Waste Processing
Once ghost crabs capture prey, they use their claws and mouthparts to shred or tear it into bite-sized pieces. The smaller food particles are then passed from the mouth towards the stomach using rhythmic motions.
Within the digestive tract, enzymes break down the food material into simple compounds like amino acids that can be absorbed. Any indigestible parts like shells or exoskeleton pieces are compacted into a pellet within the rectum.
Ghost crabs process waste differently depending on their life stage:
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Younger crabs: Release fecal pellets directly onto the sand. The incoming tide then removes the waste.
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Older crabs: Deposit feces into their sandy burrow so predators don’t detect their presence from the smell.
Proper waste removal is important, as decaying feces can attract predators to a crab’s hiding place if left on the beach.
Feeding Behavior Changes
Ghost crabs alter their feeding patterns depending on factors like:
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Age: Younger crabs scavenge more opportunistically while older, larger crabs may hunt live prey.
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Molting: Crabs stop eating for several days before and after molting to allow the new exoskeleton to harden.
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Weather: Hot, dry conditions mean less food gets washed ashore, leading to increased hunting. Cooler temperatures result in crabs staying buried and eating less frequently.
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Food availability: Crabs eat more often when large amounts of seaweed and carrion wash ashore after storms or changing tides. Long periods without new food may result in crabs moving to a new area.
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Breeding: Female ghost crabs need extra nutrition before reproducing to develop healthy eggs. This leads to increased foraging.
Ghost crabs are versatile, opportunistic feeders that utilize a variety of food sources available in their sandy beach habitat. Their ability to switch between scavenging and hunting allows them to thrive in many coastal environments around the world. Keep an eye out for these elusive crabs on your next beach trip and see if you can observe their fascinating feeding behaviors in action!
Reproduction and life cycle
Mating can occur throughout the year, and often takes place in or near the burrow of a male. Crab burrows can be up to four feet deep, and are often found hundreds of feet from the waters edge. Younger ghost crabs burrow close to the water, while older ghost crabs burrow higher up on the beach.
While mating, males release a fluid with their sperm that will harden and prevent rival sperm from reaching the females ova. Females carry developing eggs under their bodies before releasing them into the water, where larvae will develop. The average life span of a ghost crab is three years.
- The Latin name Ocypode means “swift-footed.”
- Ghost crabs do not have to return to the water to wet their gills; instead, they are able to use fine hairs located on the base of their legs to wick up water from damp sand.
- Ghost crabs can create three sounds: striking the ground with their claws, rubbing their legs together or making a bubbling sound.
- More terrestrial than any other crab in the Chesapeake Bay, ghost crabs enter the water only to moisten their gills and develop eggs. Rather than enter the water completely, ghost crabs prefer to brace themselves on the sand and allow incoming waves to wash over their bodies.
Ghost Crab Facts: the Crabs in Holes on Beaches | Animal Fact Files
FAQ
Can you keep a ghost crab as a pet?
While ghost crabs can be kept as pets, it’s not generally recommended due to their specific needs and potential for aggression. They require a large, saltwater tank with a sand substrate for burrowing, and their aggressive nature can make cohabitation with other animals difficult.
Do ghost crabs bite?
Yes, ghost crabs can bite, but it’s usually a pinch that won’t cause serious injury.
Why can’t you eat ghost crabs?
In theory, you can eat ghost crabs. But you probably shouldn’t. Their bodies are small, maxing out at perhaps three inches, containing barely a mouthful of meat. And, as noted, a ghost crab’s diet includes Portuguese man o’ wars, which are known to be a beach hazard.
Are ghost crabs harmless?
The ghost crab’s diet includes coquina clams, mole crabs, sea turtles, and shorebirds eggs.) Ghost crabs are harmless to people. Their biggest threat comes from human activity in their environment.