Pinki the tarantula molts
We came in to work to find Pinki the tarantula on her back in her desert aquarium.
Like many people who see a tarantula in this position, our first thought was "Is she dead?" She wasn't moving. Her legs were wide apart. She was on her back. She certainly appeared dead.
However, even naturalists have things to learn, and some Internet research showed that Pinki was not dead at all. She was just getting ready to molt --- shed her exoskeleton.
(Read more reasons why tarantulas are cool.)
All spiders molt, and a sign that a tarantula is getting ready to molt is that it will spin some webbing and flip to its back to help it ease the escape from its old exoskeleton.
Why spiders molt
Unlike humans, spiders don't have bones in their body. Instead, they have an exoskeleton, which is a hard outer covering that protects the inner organs and also is used to move. Spiders contract muscles attached to their exoskeleton to help them move, just like humans do, but opposite. The spider skeleton and spider joints are all on the outside instead of the inside.
However, spiders' exoskeletons can't grow with them. Made out of cuticle, the exoskeleton is extremely strong and rigid and does not expand like human bone and tissue. To increase in size, a spider must create a new exoskeleton inside the smaller, old exoskeleton and then crawl out of the old one.
Molting occurs more often when a spider is young and less often as it ages. Pinki molted in June 2017 and then again in October 2018.
How molting works
The molting process begins before we can see it, before the spider exits the old exoskeleton.
Pinki would have begun molting when her hormones told her to by secreting cuticle material inside her old exoskeleton and creating a new exoskeleton layer inside. The new layer is larger than the old, so it begins slightly softer and folded.
She would then secrete a molting fluid between the two exoskeletons, dissolving the tissue between the two layers and creating a gap.
Tarantulas then contract the abdomen to push fluids into the cephalothorax --- the fused head and upper body on the diagram below. This pressure helps the old exoskeleton lift from the new one and crack open.
This is the point that Pinki turned over onto her back. She flexed her muscles and made the old exoskeleton fall away, sliding from it in her new, flexible exoskeleton.
Right after, Pinki grew into her new "skin." She then needs to be left alone for about a week for her new exoskeleton to fully harden.
Many creatures molt, whether it be losing an exoskeleton or shedding skin. Crustaceans, caterpillars, lizards, snakes, frogs --- all of these molt to reveal a new exoskeleton or new skin as they grow.
(Read more about our animal ambassadors, like Pinki, on our Just for Kids page.)
Reasons why insects are beneficial
Insects are beneficial. For some reason, most people grow up thinking “Ew” whenever they think “Insect.” However, the vast majority of insects are actually beneficial to humans and the environment. Even those that we think of as annoying, such as mosquitoes, can actually be beneficial in some way. Mosquitoes are actually pollinators. A type of Read More »Read More
Tarantula defense mechanisms
One might think that the first thing a tarantula, like Pinki — the Chilean rose-haired tarantula at the Dickinson County Nature Center, would do to protect itself would be to bite with its venomous fangs. Yet, they actually have several warning signs to tell predators, including people, that they are uncomfortable and to not get Read More »Read More
What animals are thankful for
Every Thanksgiving, our naturalists speak at Harris-Lake Park Elementary for a grandparent program, and this year, our environmental education coordinator Bryanna Kuhlman discussed what animals are thankful for. I thought her topic was so creative that I decided to share her ideas with you. Many of the things animals are thankful for are what humans Read More »Read More
Easy pasta creatures
The Great Lakes Mall in Spirit Lake hosts an annual Festival of Trees in which local businesses and non-profits can decorate a tree for a chance to be voted to win the top prize. This year, the theme is about our local food pantry through Upper Des Moines Opportunity, and each organization that decorates a Read More »Read More
Easy and inexpensive pipe cleaner animals
I was flipping through Pinterest last night when I saw some photos of amazing miniature animal creations and realized that they were all made out of pipe cleaners. That’s something we have a lot of in the craft supply area at the nature center, so I figured it would be the perfect craft to feature Read More »Read More
Creepy but cool: How snakes can move without legs
Besides their forked tongues, probably the main thing that creeps people out about snakes is their ability to move without legs or feet. (The reason a snake sticks out its tongue, and why it’s forked.) I have to say, before I started working at the Dickinson County Nature Center, back when I was still petrified Read More »Read More
Venom and barbed hairs: Why tarantulas are actually quite cool
Spiderwebs. Big black spiders. Furry tarantulas. Halloween decorations are often centered around arachnids — the family of creatures with four pairs of legs that includes spiders, scorpions, mites and ticks — of some sort. (Teach your kids why they should appreciate all nature.) I think it’s just because spiders and their relatives are considered creepy with their many Read More »Read More
Really interesting explanation!