#dromiidae

[artifacts-and-arthropods]

Lamarckdromia beagle: this species of crab wears living sea-sponges as protective "hats," with each crab selecting a sea-sponge, trimming it, and then draping the tailored sponge across its carapace

Above: Lamarckdromia beagle wearing a sea-sponge on its head

Last year, a newly-classified species of sponge crab known as Lamarckdromia beagle was discovered off the coast of Western Australia. This species belongs to the Dromiidae family, which contains many different crabs that are known to use living sea-sponges and ascidians to protect themselves from predators.

Above: Lamarckdromia beagle without the sea-sponge

This article explains how the crab's peculiar "hat" is used:

Dr. Andrew Hosie, a curator of crustaceans and worms at the Western Australian Museum, says that sponge crabs have hind legs that are specially adapted for holding their protective hats. “The sponge or ascidian just keeps growing and will mould to the shape of the crab’s back,” he says. "It will never attach. It forms a nice cap that fits quite snugly to the top of the crab."

Similar to how hermit crabs use shells for protection, the sponges help Dromiidae crabs remain camouflage from predators such as octopuses and other crabs.

The sponges can be bigger than the crab itself, and also provide a chemical deterrent. “Some of the compounds that these sponges are producing are very noxious,” says Dr. Hosie. “There’s not a lot of active predators that would be interested in munching through a sponge just to get to a crab.”

Sponge crabs come in many different shapes and sizes, but this particular species has a dense, shaggy coat of bristles, which makes it look even more peculiar. The other crabs in genus Lamarckdromia are much less fuzzy, and there are many sponge crabs that have no "fur" (i.e. layer of bristles) at all.

Some of the other examples of sponge crabs from the Dromiidae family are depicted below.

Sources & More Info

The Guardian: "Fluffy" Crab that Wears a Sponge as a Hat Discovered in Western Australia

Reef Builders: Lamarckdromia beagle: A New Species of Sponge Crab from Australia

Zootaxa: Sponge Crabs of Western Australia and the Northwest Shelf with Descriptions of New Genera and Species

Live Science: An Extremely Fuzzy Sponge Crab

Australian Broadcasting Corporation: New Sponge Crab Species Named After Charles Darwin's Research Boat

Slate: Meet the Fluffy Crab that Wears a Hat

[herpsandbirds]

Bristled Sponge Crab, Austrodromidia octodentata, family Dromiidae, South Australia

Photograph by Steve Johns

[astronomy-to-zoology]

Dromia personata

...is a species of dromiid crab that occurs in the North Sea, Mediterranean Sea and parts of the northeastern Atlantic Ocean. They are typically found in areas ranging from the lower shore to depths of around 30 ft, however they are often found in caves as well. Like several other unrelated crab species the last two pairs of leg of D. personata are positioned dorsally and are used to hold a sponge in place as a form of camouflage.

Classification

Animalia-Arthropoda-Crustacea-Malacostraca-Decapoda-Brachyura-Dromiidae-Dromia-D. personata

Images: Hans Hillewaert and Tihomir Gržinčić

*they totally look like they're wearing little beanies too.

[astronomy-to-zoology]

Dromiidae

(Sponge Crabs)

Dromiidae is a family of crabs noted for their habit of putting a live sponge onto their "backs" to use as a shelter or camouflage. they hold them in place with a pair of modified back legs which bend upwards. Once the sponge is on the crab the crab will actually trim the sponge to fit the crabs needs using its claws, this is no harm to the sponge and actually benefits it as the sponge can get new bits of organic material from the waterstream as the crab moves around. it also looks like the crab is wearing a huge beanie.

Phylogeny

Animalia-Arthropoda-Crustacea-Malacostraca-Decapoda-Brachyura-Dromiidae

Source,Source