Crabs can deliver painful pinches with their claws. The level of pain varies by crab species, based on the size and strength of their claws. Determining the most painful crab pinch is difficult, but researchers have conducted studies analyzing claw strength across crab species.
Measuring Crab Pinching Force
Researchers use specialized equipment to measure the pinching force of crab claws. A common method is to attach sensors to their claws, provoke the crab to pinch, and record the force in newtons or pounds per square inch (PSI). Studies have tested various crab species to compare their relative pinch strengths.
Several physical factors determine pinch force:
- Claw size – Larger claws can exert more force.
- Claw muscle mass – More muscular claws are stronger.
- Mechanical leverage – The claw’s structure affects force amplification.
- Species attributes – Some species have innate stronger claws.
The claw’s mechanical leverage is important. Crabs can generate a force 5-10x their muscle strength by using joints and the shape of their claws. Even small crabs can produce dangerously strong pinches.
The Strongest Pincher: Coconut Crab
Research suggests the coconut crab (Birgus latro) has the most powerful pinch of any crab species. This very large land crab lives on islands in the Indian and southern Pacific oceans. It has massive claws that can reach over 9 inches (23 cm) long.
In a 2009 study, a coconut crab achieved an estimated pinch force of 3,300 newtons (740 lbs of force). This is equivalent to the bite force of an adult lion. Their claws are capable of cracking open coconuts, hence their name.
A 2016 study tested the claws of several coconut crabs. The strongest individual achieved a pinch force of 3,541 newtons (795 lbs). The average pinch force was 1,765 newtons (396 lbs).
For comparison, studies have measured the claw strength of other common crabs:
| Crab species | Average pinch force |
|---|---|
| Blue crab | 182 Newtons (41 lbs) |
| Dungeness crab | 91 Newtons (20 lbs) |
| Rock crab | 73 Newtons (16 lbs) |
The coconut crab’s pinch force dwarfs these smaller crab species. Their massive claws, coupled with bigger muscles and stronger leverage, allow them to crack objects these crabs cannot.
Other Powerful Pinchers
While the coconut crab pinches hardest, a few other crab species can deliver powerful and painful pinches:
Japanese spider crab
The Japanese spider crab has a claw span reaching 12 ft (3.7 m). Their claws are weaker in proportion to body size than other crabs, but can still exert over 130 newtons (29 lbs) of force. Getting pinched by their baseball-sized claw tips would be very painful.
Atlantic blue crab
The Atlantic blue crab has thick, strong claws for its size. Large males can deliver around 200 newtons (45 lbs) of pinch force. Their pincers are strong enough to break a human finger bone.
European edible crab
This crab, popular in European fisheries, grows claws up to 2.75 in (7 cm) long. Their muscular claws can exert over 90 newtons (20 lbs) of pinching force, enough to draw blood from human skin.
Giant Tasmanian crab
This Australian crab grows up to 16 lbs (7.3 kg), with claws over 3 inches long. While their pinch force hasn’t been measured, it’s likely over 100 newtons (22 lbs), given their massive claws.
Why Do Crabs Pinch?
Crabs mainly use their claws for feeding, but also use pinches for self-defense and competition. Here are some reasons why crabs pinch:
- Capture prey – Crabs seize and crush prey with their vice-like claws.
- Crack open shells – They crack mollusk shells or coconut husks with their claws.
- Excavate burrows – Crabs use claws to dig out sand or mud to make burrows.
- Intimidate rivals – Pinching and claw waving threatens competing crabs.
- Fend off predators – Powerful claws can deter potential predators.
- Defend territory – Crabs pinch to scare away intruders.
Crabs will pinch humans in self-defense if stepped on or handled roughly. Even relatively light pinches can be quite painful.
Pain Level from Crab Pinches
There are no scientific measurements of pain levels from crab pinches. However, first-hand accounts provide insight into how painful the bites can be:
- Sharp, piercing pain – The pinching force of claws penetrating skin causes intense pain.
- Possible tearing of skin – Powerful crabs can tear flesh if the pinch breaks skin.
- Persistent ache – Soreness and aching can remain for hours or days afterwards.
- Possible bleeding – Broken skin from the pinch can cause bleeding.
- Hand and finger impacts – Pinches to the hands or fingers can disrupt delicate nerves and bones.
- Infection risk – Bacteria from crab claws can infect the wound.
The most powerful crabs, like coconut crabs, could potentially even break bones with their claw strength. A full-force pinch from a large crab is likely among the most painful a human can experience.
Preventing Painful Crab Pinches
You can reduce the risk of being painfully pinched by following these safe handling practices:
- Wear thick gloves – Protect your hands with thick rubber or leather gloves.
- Grip the back shell – Pick up crabs only by the back of their shell to restrain claw movement.
- Keep crabs chilled – Cold temperatures make crabs sluggish and less likely to pinch.
- Support the legs – Hold crabs gently but securely so they don’t feel the need to pinch.
- Keep hands clear – Avoid reaching directly over the top of crabs where they can easily pinch.
- Be aware of surroundings – Watch where you step so you don’t accidentally tread on a buried crab.
Take care when handling crab claws, even when the crab is dead. The muscles may still reflexively close the claw and pinch if triggered.
Treatment for Crab Pinches
If you do suffer a painful crab pinch, here are some first aid suggestions:
- Wash the wound – Thoroughly clean any broken skin with soap and water.
- Apply antibiotic cream – Use an antibiotic ointment to prevent infection.
- Bandage the area – Wrap the wound with sterile gauze or a bandage.
- Take anti-inflammatory medication – An anti-inflammatory like ibuprofen can help reduce swelling and pain.
- Ice the area – Apply an ice pack to relieve pain and swelling.
- Get medical help for severe pinches – Seek medical care if the wound or pain seems extreme.
Conclusion
Of all known crab species, the coconut crab has the most powerful pinch based on direct measurements of claw strength. Its massive pincers can exert forces over 3,000 newtons, easily capable of cracking coconuts or breaking bones. Other very large crab species may rival the coconut crab, but have not been tested.
Any full-size crab is capable of a painful pinch, especially if it latches onto a sensitive area. Even relatively small crabs can generate enough force to break skin or cause bruising. Appropriate handling techniques, gloves, and basic first aid can help reduce the risk and pain of accidental crab pinches.
