Ancient Assassin: The Life of a Bark Scorpion

Great indeed is the power of the dragon as the sun,
Yet humbly and slowly it meanders its way shy,
Minuscule indeed is the power of the tiny scorpion,
Yet it swaggers its tail and boasts to the sky. ~ Old Thai verse

 

Ancient Greeks, Romans, Egyptians, and Babylonians included Scorpions in their mythology. 

Public domain image by Johannes Hevelius 1690

Ancient Assassin

Something lurks in the darkness of Grand Canyon, keeping campers awake. Its sting - more feared than a lion's attack. Its hunting ability - so revered it has been immortalized in the night sky. An ancient assassin - it has walked the earth for over 400 million years.

It's the SCORPION.

Of the over 1400 species of scorpion found on Earth, the most venomous in the United States - the bark scorpion (Centruroides sculpturatus) - calls Phantom Ranch home. Often misunderstood, the efficiently evolved arthropod represents death and the cycle of life.

 

Motherhood is dangerous work.  Female scorpions are much slower and more likely to be captured by predators while carrying their young.

© 1978 Paul Berquist ASDM Digital Library

Piggyback Ride

Given common misunderstandings, you might be amazed to learn scorpion life begins with a piggyback ride! A female scorpion gives birth to live young. She will scoop as many as 30 babies onto her back and carry her young for up to 3 weeks. The first time the babies shed their exoskeletons, they leave the safety of their mother's care. On their own, young scorpions struggle to survive.

There are many desert creatures that prey on these growing arthropods. Bats, tarantulas, birds (especially owls), mice, lizards, and more consider scorpions to be a meal.

The light tan coloring of the bark scorpion acts as camouflage, however, against rocks, bark, and leaf litter.

 

Fully grown at 2.5 inches (6.35 cm), these tiny predators are easy to miss.

Licensed under Creative Commons © Noah Charney

Fight or Flight

When confronted by a predator, a scorpion must decide to stay and fight or to run away. If successful in these tactics, it can live to be 5-7 years old.

Instinct tells most scorpions that it would be futile to fight. When they run, the majority of their attackers cannot catch them. And when the scorpion is on the attacking end, their insect-sized victims do not stand a chance.

 

Otherwise nearly invisible against the rocks and leaf litter, this Bark Scorpion reveals itself under an ultraviolet light.  It sits motionless waiting to ambush passing prey.

NPS photo

Ambush

Bark scorpions are efficient ambush predators. They spend the day hiding in dead or downed tree bark or underneath rocks to wait out the scorching temperatures of the day.

They crawl out of hiding at night to hunt. Nearly invisible, they lay in wait for passing prey. Using fine hairs on their legs and comb-like organs on their undersides called pectines, scorpions sense the vibrations of a passing meal. Attacking with lightning speed and impeccable precision, scorpions grab their victims in their pincers and simultaneously sting them. This action can be missed in the blink of an eye. Their venom paralyzes the prey making it easier to consume.

 

They will eat cockroaches, crickets, moths, spiders, and other insects. Scorpions feed several times a week but they can go months without eating, including the cold Grand Canyon winters.

Winter Sleep
As temperatures drop to near freezing, bark scorpions prepare for hibernation. They seek sheltered areas, often in buildings, to wait out the coldest part of the year. They may gather in groups of 40 or more. While many scorpion species are cannibalistic and do not enjoy the company of other scorpions, bark scorpions do not mind snuggling up for the winter. During this time, scorpions will not eat at all. Their next meal will be in spring, when evening temperatures are consistently over 73 degrees Fahrenheit (23C). As these scorpions awake from hibernation, the cycle of survival for this simple cold-blooded killer continues.

 

The best way to see scorpions is with a park ranger and an UV light. 

NPS photo.

The Scoop on Scorps

The secrets of these ancient assassins are revealed each night at Phantom Ranch. Ask a Park Ranger to take you on a scorpion hunt.

Do not worry; bark scorpions are lethal to their prey but not to humans. Many people compare the sting of the bark scorpion to that of an intense bee sting. If stung, relief can be found with ice, aspirin, and time. Take advantage of the opportunity to witness the cycle of life among scorpions.

 

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Related Information

Grand Canyon Invertebrate Species Collection (1.7MB XLS File)

Grand Canyon Threatened & Endangered Species List (52kb PDF File)

Arizona Game and Fish Web Site