Decorator crabs have little hooks on their arms and legs that they use to attach things to themselves. These hooks are called setae, and sort of works like Velcro. Photo: Paul Sorensen.
Once the crabs find an item that they want to use as a covering on their shell they use their claws to snip of a piece of the chosen covering. They use a special gland to release discharge that will harden in saltwater and use this to stick the covering to their carapace (shell). Photo: Paul Sorensen.
The decorator crab, like its name suggests, decorates itself for camouflage. They are often found on pier pylons that are covered in other sponges, seaweeds, kelps and other small marine life including sea horses and sea stars. Photo: Paul Sorensen.
Welcome to the Marine Mili series, a regular column about all things marine! During this series I aim to inspire people to want to protect our oceans and all the marine life that call our oceans home. Hopefully after reading each column, you would have learnt something new, including what we can do to help protect and preserve our oceans. You can follow me and my journey on my Instagram page: _marine_mili.
The decorator crab, like its name suggests, decorates itself for camouflage.
There are hundreds of species of decorator crabs (a species of spider crabs).and they all are crustaceans.
They use sponges, seaweeds, algae, bryozoans, anemones and sometimes even other creatures, to decorate themselves. This can include other little crabs, shrimp, and sea stars.
These creatures help the decorator crabs blend in. In return the creatures that live on the crab's shell get an ongoing supply of new water so they can filter feed.
The crabs decorate themselves to hide from predators such as pacific halibut, octopuses, and other various fish species.
Decorator crabs have little hooks on their arms and legs that they use to attach things to themselves. These hooks are called setae, and sort of work like Velcro.
Once the crabs find an item that they want to use as a covering on their shell, they use their claws to snip off a piece of the chosen covering.
Then they use a special gland to release discharge that will harden in saltwater and use that to item the covering to their carapace (shell).
Decorator crabs can be found underneath piers and in rocky intertidal zone where they can easily camouflage.
Although the crabs often live on pier pylons, because the pylons are covered in other sponges, seaweeds, kelps and other small marine life including sea horses and sea stars, it is hard to spot the crabs as they camouflage so well.
As crabs grow, they moult which means they leave their old shells and grow a new one that fits their body better. They do this as their shell is not flexible and doesn’t grow with them.
When decorator crabs moult, they reuse most of their old decorations, and usually keep the same decorations for their entire life unless they change environments. In which case, they will adjust their camouflage to the new area.
However, they don’t often move to locations that look completely different.
