Life behind a Hermit Crab's Shell

By Mia Stertzer


When you see a hermit crab, what do you think? Small, ugly, or dumb? If that's what you think, you're absolutely wrong. Hermit Crabs are adventurous, smart, and interesting. When you walk in a mall and see a kiosk selling hermit crabs with painted shells, do you think, pretty, cute, or beautiful? Well you're wrong on that too, that paint will soon chip off and the hermit crab will eat it. It can poison the hermit crab and potentially kill it as well. There are a lot of things you can guess about hermit crabs from the outside, but most people don't know the true facts on the inside. By the end of this presentation, I hope you think differently and become more educated and passionate about these little critters.


  • Hermit crabs are scientifically named Paguroidea (pag-ear-oadia)

  • Hermit crabs weight ranges from 200-500g (7-18oz.)

  • They are omnivores

  • 500 species

  • Lifespan is 1-10 years

  • The size of a hermit crab is 2-10 cm (.8-4 in)

  • Hermit Crabs conservation status is threatened

  • Their skin is their shell

  • They can be Green, Red, Blue, Yellow, Orange, Brown, Pink, and White

  • Average litter size is 200

  • Natural habitat is coastal water



  • Painted shells can be toxic to the hermit crab

  • They need access to a bigger shell when they get bigger

  • The shell can’t have holes and must fit snugly

  • Ideal shell helps maintain moisture level--necessary for survival

  • Some hermit crabs will change shells multiple times a week, or everyday, while other hermit crabs will stick with one shell.

  • Hermit crabs may be unwilling to move if they’re cramped in their shell.

  • You can boil his new shell to make sure no germs are in it.

  • You can determine the size of a hermit crab’s shell by the size of their claw. (⅛ inch larger than the size of his big claw.



  • They eat fish, worms, and plankton

  • Hunted by fish, shark, and cuttlefish

  • They enjoy variety

  • They cannot eat processed food

  • Sugar and table salt can be harmful

  • They eat baby food, and the especially enjoy fruit flavors

  • You can give a hermit meat if it’s not seasoned with spices or table salt

  • Don’t put painted shells in a hermit crab’s tank, because soon paint will start chipping off and the hermit crab will eat it and become infected with the toxins in the paint.

  • Hermit crabs will store food in their shell

  • Hermit crabs poop little logs, like fish, out not ball shaped.

  • Hermit crabs poop in their shells and then get rid of them when the change shells

  • They release waste gases near their eye, which makes a farting sound.
  • Hermit crabs drink from a sponge



  • Jonathan Livingston Crab and Crab Kate

  • They turned 29 in August

  • Carol Ann Ormes is the caretaker of these crabs

  • Jonathan is an explorer and likes to run around--he once climbed the bathroom wall!

  • Once Jonathan fell and made a nickel size hole in his shell

  • After that, she gave him a bath

  • The hermit crabs like a moist environment


Interview with Emily

How long have you had your hermit crabs?

"4 months."

How many times do you clean their tank?

"Once a week."

What do you feed them?

"I feed them two different mixes of hermit crab food from the pet store so they can have variety."

How many times do you feed them a day?

"I give them fresh food each day."

Do you interact with them?

"I'll let them crawl on my desk when I clean their cages, but they normally stay in their cages"

Where did you get your hermit crabs?

"The pet store."

Are their shells painted?


How many hermit crabs do you have?


What type of environment do you put your hermit crabs in, and why?

"There is sand, shells, water, and things that can hide in, because I try to get things from where they naturally live."


More in-depth about Herbie and Smiley

Jackson and his family won Smiley at a carnival ring toss. Smiley is the football player, (as Jackson explained,) and they received him in a smiley face shell--hence the name. Herbie, the one with the more shell-like-shell they adopted from Pets Mart. Now these two fine young hermit crabs live a life of peace with each other in the custody of Jackson.

To further explain the molting process...

Hermit Crabs molt as a way of growing and getting bigger. They shed their original or past exoskeleton and develop a new one. This process can take up to a month. During this time the hermit crab might look dead because they can't move. Their muscles are sore because they are unable to regain it. After molting the hermit crab is much bigger, as mentioned by Jackson.


  • Fertilized eggs grow attached to the female’s abdomen

  • The left claw is larger for protection

  • Their antennas are the organs that they use to smell

  • Their eyes are on the end of optic stalks

  • Hermit crabs can be found around the world

  • Hermit crabs have not ever been bred successfully in captivity