A somewhat traumatizing time-lapse released by the Cincinnati Zoo and Botanical Garden in Ohio shows a Mexican red-kneed tarantula's seven-hour molting process condensed into just 40 seconds.
Named for its rust-colored leg joints, both male and female spiders will molt throughout their lifetimes to accommodate growing bodies. The exoskeleton acts as external housing that protects the spider’s internal organs – much like our skin – but it doesn't grow with the spider. Every year or so, the tarantulas will shed their stiff, old exoskeletons to reveal a newer, fresher body as the arachnid gets larger.
Named Baby Fang, "she was first raised at home by Theresa Austing, a recently retired keeper from the Cincinnati Zoo’s World of the Insect," Mandy Pritchard, team leader of the World of the Insect, told IFLScience. "Theresa says she was the size of a dime when she first got her at 10 days old in 1997."
The video shows the spider lying on its back twerking out of its skeleton. During the molting process, the tarantula contracts its abdomen to push fluid into its upper body (cephalothorax). This fluid increases pressure on the already tight exoskeleton and essentially ruptures weak spots. The spider will twitch, stretch, and kick its legs to work itself through holes until the entire exoskeleton is shed, resulting in a perfect replication of the spider sans head and fangs.
"All arthropods molt in order to grow larger. Adult tarantulas molt once a year or once every other year depending on age and species," said the zoo in a Facebook post. "Young tarantulas molt more often. This time-lapse video shows the 7-hour process of our red-kneed tarantula's molt."
The new exoskeleton doesn’t just look fresher, it’s also softer and more sensitive before hardening within a few days. The ends of a tarantula’s legs act as feelers, sensing smells, tastes, and vibrations.
Depending on their habitat, males will typically reach maturity after four years and will live just a year following their last molt. Females reach maturity in six to 10 years and can live to be as old as 25.
The mildly poisonous but docile red-kneed tarantula (Euathlus smithi) is native to Mexican deserts and scrublands. Due to increasing demands in the pet trade and habitat destruction, the red-kneed tarantula is a species at risk under the IUCN Red List and is protected by the Convention on International Trade in Endangered Species (CITES).
Baby Fang has been living at the zoo since 2008. Pritchard says she can occasionally be seen on exhibit, but is currently behind the scenes while she recovers from molting.