''Dardanus arrosor'', the red reef hermit or Mediterranean hermit crab, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

hermit crab Hermit crabs are anomuran Decapoda, decapod crustaceans of the superfamily (taxonomy), superfamily Paguroidea that have adapted to occupy empty scavenged mollusc shells to protect their fragile exoskeletons. There are over 800 species of hermit c ...

.WoRMS
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Description

Carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...

of ''Dardanus arrosor'' can reach a length of . The color varies from bright red to bright orange. The eyestalks are robust, not very long, dilated at the tip and alternately streaked with red and white. The eyes are bluish. Claws show hair-like spines and warty tubercles. The left claw is more developed than the right one, but in both claws the tip is black or yellowish. The abdomen is asymmetrical, bare and hidden within a shell.Lesley Orson Wood,Lawson Woo
Malta, Comino and Gozo: Over 80 Top Dive and Snorkel Sites
Globetrotter dive guide (2nd ed.). New Holland Publishers. .
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Biology

This species breed between July and August. These crabs show the striking behavior of living within empty shells of conches (usually shells of '' Bittium latreillii''), often decorated with

sea anemone Sea anemones ( ) are a group of predation, predatory marine invertebrates constituting the order (biology), order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. Sea anemone ...

s (usually ''

Calliactis parasitica ''Calliactis parasitica'' is a species of sea anemone associated with hermit crabs. It lives in the eastern Atlantic Ocean and Mediterranean Sea at depths between the intertidal zone and . It is up to in size, with up to 700 tentacles, and is ve ...

''). The larvae have a symmetrical shape, but gradually they develop an asymmetrical abdomen that this crustacean will hide in a periodically replaced shell. The relationship with the anemone is truly

symbiotic Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...

, since the anemone gains scraps of food from the hermit crab, while the crab benefits from the anemone's stinging

tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

s deterring

predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

s.D. M. Ross, L. Sutto
The Association between the Hermit Crab Dardanus arrosor (Herbst) and the Sea Anemone Calliactis parasitica (Couch)
/ref> This crab is an opportunistic

scavenger Scavengers are animals that consume Corpse decomposition, dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a he ...

and predator. It feeds on decaying matter, on live crabs and small fishes.

Distribution

This widespread species can be found in the Atlantic coasts, in the

Mediterranean Sea The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...

, in the

Red Sea The Red Sea is a sea inlet of the Indian Ocean, lying between Africa and Asia. Its connection to the ocean is in the south, through the Bab-el-Mandeb Strait and the Gulf of Aden. To its north lie the Sinai Peninsula, the Gulf of Aqaba, and th ...

, in the

Indo-West Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the s ...

(

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

and

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

).Sea Life Base
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Habitat

This species inhabits continental shelf and slope. It usually lives on sandy substrate, on coastal detritic bottoms and on bathyal muds, from a few meters up to depths of .

References

{{Taxonbar, from=Q875919 Diogenidae Crustaceans of Brazil Crustaceans described in 1796