Decorator Crab | Oceana
Home / Decorator Crab

Marine Life Encyclopedia

Cephalopods, Crustaceans, & Other Shellfish

Decorator Crab

Superfamily Majoidea

Distribution

Worldwide

ECOSYSTEM/HABITAT

Varied

FEEDING HABITS

Foraging Omnivore

TAXONOMY

Superfamily Majoidea (around 75% of species in this superfamily are classified as decorator crabs)

The term “decorator crab” describes many different crabs found worldwide, including several different species of spider crabs, harlequin crabs, moss crabs, little seaweed crabs, and toothed crabs.

In general, decorator crabs are opportunistic when looking for camouflage, similar to how colorful hermit crabs scavenge their shells. The crab will select pieces of seaweed, coral, rocks, or even other small animals from around its habitat and then fastens them to hooked bristles on the back of its shell. This camouflage helps protect the crab from predators and so long as they stay in the general area of where they scavenged, the crab can look near invisible on the reef or seafloor.1

The hooked bristles along its body are known as setae and they act very much like Velcro. This allows for the crab to change what is hooked to its body if needed – for example, a crab may take off a ring of seaweed scavenged earlier if it finds a stinging anemone that could better scare off a hungry fish or larger crab.2

Like many crabs, decorator crabs molt as they grow, shedding their inflexible shells when they become too small. The soft crab is incredibly vulnerable during this process and hides from predators as the new shell hardens. Many decorator crabs recycle their old decorations from their old shell, moving them carefully to the new shell as it hardens.

Fun Facts About Decorator Crabs

1. Living animals, including anemones and sea urchins, often wind up used as camouflage by decorator crabs.

2. Some crabs that are large enough to defend themselves don’t decorate – but plants and animals can latch on anyway, seeking protection on the larger crab.

3. These crabs easily blend in with the environments and often stay still in the face of predators.

4. The relationship between decorator crabs and animals on their shells is often mutualistic, the other animals feeding on what the crab leaves behind.

5. Can be mistaken for seaweed and coral on the move.

Additional Resources:

1. UC Davis

2. Behavioral Ecology

Get Involved

Donate Today

SUPPORT OUR WORK TO PROTECT THE OCEANS BY GIVING TODAY

With the support of more than 1 million activists like you, we have already protected nearly 4 million square miles of ocean.

Donate Now

TAKE ACTION NOW

Support policy change for the oceans

Decision-makers need to hear from ocean lovers like you. Make your voice heard!

Sign Now

VISIT OUR ADOPTION CENTER

SYMBOLICALLY ADOPT AN ANIMAL TODAY

Visit our online store to see all the ocean animals you can symbolically adopt, either for yourself or as a gift for someone else.

Shop Today

DOWNLOAD OCEAN ACTIVITIES

HELP KIDS DISCOVER OUR BLUE PLANET

Our free KELP (Kids Environmental Lesson Plans) empower children to learn about and protect our oceans!

Learn More

FEATURED CAMPAIGN

Save the Oceans, Feed the World

We are restoring the world’s wild fish populations to serve as a sustainable source of protein for people.

Learn More

More CAMPAIGNs

Protect Habitat

Bycatch

Plastics

View All

CONTACT

Oceana International Headquarters
1025 Connecticut Avenue, Suite 200
Washington, DC 20036 USA

General Inquiries
+1(202)-833-3900
info@oceana.org

Donation Inquiries
+1(202)-996-7174
wavemaker@oceana.org

Press Inquiries
+1(202)-833-3900
press@oceana.org

OCEANA'S EFFICIENCY

BECOME A WAVEMAKER

Sign up today to get weekly updates and action alerts from Oceana.

SHOW YOUR SUPPORT WITH A DONATION

We have already protected nearly 4 million square miles of ocean and innumerable sea life - but there is still more to be done.

Donate Now

QUICK LINKS: