| Calcinus elegans | |
|---|---|
 | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Crustacea |
| Class: | Malacostraca |
| Order: | Decapoda |
| Infraorder: | Anomura |
| Family: | Calcinidae |
| Genus: | Calcinus |
| Species: | C. elegans |
| Binomial name | |
| Calcinus elegans (H. Milne-Edwards, 1836) | |
| Synonyms [1] | |
| |
Calcinus elegans, also known as the blue line hermit crab, is a small, tropical hermit crab.
It features the typical body plan of a member of the phylum Arthropoda: a segmented head, a thorax, and an abdomen. As a member of order Decapoda, this organism has 5 pairs of legs, with one pair having developed into sharper claws, or chela. This hermit crab supports the heavy shell of a gastropod with its four pairs of ambulatory legs, shielding its soft abdomen inside. It features a unique and exotic color pattern, sporting alternating bright blue and black stripes on its legs and olive green chela with white speckles on the ends. Two bright blue eyes peer out of the shell alongside two orange antennae and two orange antennules. The organism also features maxillae to help guide particles of food into its mouth. Some morphological differences arise based upon the geologic habitat the organism resides in. For instance, some individuals of Calcinus elegans found in Hawaii display orange bands on their ambulatory legs, differing from the pure blue bands found in individuals of the Indo-Pacific. [2] Calcinus elegans is distinct from all other species in the Calcinus genus as it is the only one to be covered with small hairs known as seta. [2]
Calcinus elegans primarily makes its home in shallow tidal and subtidal regions found within the Indo-West Pacific, stretching from Eastern Africa to island chains just south of Hawaii. [3] [4] Some of them can also be found living in the tropics of the U.S. Virgin Islands near Puerto Rico. [5] Some sightings have even been reported at various locations in Japan including the Ryukyu Islands, Izu, Ogasawara, Kochi, Boso, and the Kii Peninsula. [2] Its distribution primarily follows the path of the equator; these places are known to have tropical conditions such as higher ocean temperatures, clear waters, and little primary productivity. These habitats have a depth range of 0–20 meters (0–66 feet), a sea surface salinity range of 30-35 ppt, and a sea surface temperature range of 20–30 °C (68–86 °F). [3]
Each member of the Calcinus elegans species will select a shell for itself, occasionally switching shells with other species members or empty shells it finds during its lifetime. Shell exchanges could be performed due to the current shell being structurally unstable, too heavy, or perhaps too large or small. Shell exchange was also found to occur within the Calcinus genus as a result of interspecific competition, as individuals of a certain species battle for a perfect shell. [6] Some studies show that the sex of the individual may also play a role in the competition; this behavior is observed in individuals of Calcinus verrilli. [7] These shells are primarily used to provide shelter and protection from predators as well as the surrounding environment. Individuals of Calcinus elegans were found to show a preference for the shells of dog whelks, but were also observed wearing shells of the snakehead cowrie and variable worm. [8] This shows that the species exhibits a variety of morphology.
Shell shape was also found to influence the distribution of Calcinus elegans within their habitat. Those with cowrie or variable worm shells often remained in shallow waters, refraining from entering the subtidal areas out of fear of predation. When tested, cowrie shells and variable worm shells proved to be a weak defense system against the predators of the subtidal. Calcinus elegans that wear the shells of dog whelks prefer to live within the subtidal region, as their shell shape allows them to effectively deter predators. [8]
Shell shape shows no significant impact upon the travel rate to obtain food for individuals of Calcinus elegans. [8] Therefore, there is no select locomotive advantage of wearing a certain species’ shell.
Studies conducted using simulated surges show that shell shape influences the ability of Calcinus elegans to withstand wave action. Individuals wearing shells of dog whelks were proven to resist surge much more effectively than those with snakehead cowrie or variable worm shells. [8]
Calcinus elegans relies heavily on its keen sense of smell for detecting danger in the surrounding environment. This hermit crab is constantly wary of not only the smell of its predators, but the smell of gastropod shells being broken. As it relies on its gastropod shell for protection, Calcinus elegans knows that such a smell indicates that a predator is nearby and on the hunt. Usually, Calcinus elegans will attempt to find shelter or a place to hide from its predators. In the event that it is unable to locate shelter, Calcinus elegans will withdraw into its shell for defense, only emerging when it feels safe or the scents of danger have passed on. Studies have shown that the amount of time that Calcinus elegans spends withdrawn into its shell is partially determined by what species of gastropod the shell belonged to. [9]
The blue line hermit crab shows a sign of remarkable intelligence. These organisms will traditionally engage in unique behaviors before mating. Some such examples include the male rotating the female’s shell or rubbing their chilipeds, or claws, around the opening of the female’s shell. Unlike most crustaceans, Calcinus elegans does not perform a shell exchange during mating. [10]
Calcinus elegans are nocturnal omnivorous detritivores, exploring seagrass beds at night to scavenge for detritus and larger decaying plant and animal matter. [5] [11]
Ocean acidification and a continual decline in the ocean’s pH will likely have drastic consequences for hermit crabs such as Calcinus elegans. The shells of hermit crabs, primarily composed of calcium carbonate, are easily susceptible to a decline in pH. Low pH environments degrade calcium carbonate rapidly, creating a large amount of structural instability within the hermit crab’s primary defense system. Without proper protection from sturdy shells and a decline in the number of suitable shells within the environment, the population of Calcinus elegans, and other hermit crabs may begin to drop. Studies have also been performed that indicate that the resulting stress of ocean acidification could be impacting the hermit crabs’ sense of smell. Insufficient sensory stimuli were found to reduce both feeding behavior and even the rate of shell exchange. [12] As stated before, the sense of smell is key to the survival of Calcinus elegans. If inhibited, many individuals may have difficulty sensing predators, and as such, populations could decline.
As Calcinus elegans primarily relies on the shelter of its shell for protection and defense, its primary predators are individuals who have adapted to breaking gastropod shells. The white spotted eagle ray is one such predator. Found in Australia and Taiwan's Penghu Islands, this organism uses unique crushing plates in its mouth to shatter the shells of its prey. It feeds on mollusks, gastropods, and members of the Diogenidae family, which includes hermit crabs such as Calcinus elegans. [13]
While typically reclusive, hermit crabs will on occasion forge a relationship with other marine organisms. Some cnidarians use the hard surface of hermit crab shells to settle and grow polyps. The cnidaria aid in defending the crab from predators using their stinging cnidae and may reduce the need for frequent shell exchange. In return, the hermit crab provides them a settling ground as well as transport to new environments, which may contain more nutrients for the cnidaria in the form of detritus or microorganisms. However, relationships with other organisms can prove to be complicated and are not always symbiotic; some cnidaria interfere with reproduction and may even increase a hermit crab's risk of predation. These relationships have to be carefully considered so that the benefits to the hermit crab outweigh the costs. [14] If the cost is too high, the hermit crab may abandon its shell and locate a replacement.
Some algae also use the heavy shell of Calcinus elegans as a settling ground. Many of its shells have been found crusted with coralline algae. This algae provides a strong and smooth surface for coral polyps to settle on, possibly being responsible for the symbioses that can occur between corals or other cnidarians and hermit crabs. [15]
Hermit crabs are anomuran decapod crustaceans of the superfamily Paguroidea that have adapted to occupy empty scavenged mollusc shells to protect their fragile exoskeletons. There are over 800 species of hermit crab, most of which possess an asymmetric abdomen concealed by a snug-fitting shell. Hermit crabs' soft (non-calcified) abdominal exoskeleton means they must occupy shelter produced by other organisms or risk being defenseless.
The Caribbean hermit crab, also known as the soldier crab, West Atlantic crab, tree crab, or purple pincher, is a species of land hermit crab native to the west Atlantic, Bahamas, Belize, southern Florida, Venezuela, the Virgin Islands, and the West Indies. Adults burrow and hide under the roots of large trees, and can be found a considerable distance inland. As with other terrestrial crabs, they use modified gills to breathe air. Their shells help maintain the humidity necessary for gas exchange to function.
The Australian land hermit crab is a terrestrial hermit crab species, native to Australia. It is a nocturnal, omnivorous crustacean. They are gregarious and thrive in tropical areas near water.
The halloween hermit crab, also known as the striped hermit crab or orange-legged hermit crab, is a brightly colored aquatic hermit crab of the family Diogenidae. Besides its ability to routinely clean algae in aquaria, the halloween hermit crab's festive striped coloration also appeals to enthusiasts; it is considered the most brightly colored hermit crab in normal aquarium use.
Coenobita brevimanus is a species of terrestrial hermit crab belonging to the family Coenobitidae, which is composed of coastal living terrestrial hermit crabs. From there it belongs to the genus Coenobita, one of two genera split from the family, which contains sixteen species. The Latin origins of the species name, brevimanus, come from the adjective brevis ("small") and the noun manus ("hands"). It is known as the Indos crab or Indonesian crab because it is primarily distributed throughout the Indo-Pacific.
Pagurus longicarpus, the long-wristed hermit crab, is a common hermit crab found along the Atlantic and Gulf coasts of the United States and the Atlantic coast of Canada.
The coconut crab is a species of terrestrial hermit crab, also known as the robber crab or palm thief. It is the largest terrestrial arthropod in the world, with a weight of up to 4.1 kg (9 lb). It can grow to up to 1 m in width from the tip of one leg to the tip of another. It is found on islands across the Indian Ocean, and parts of the Pacific Ocean as far east as the Gambier Islands and Pitcairn Islands, similar to the distribution of the coconut palm; it has been extirpated from most areas with a significant human population, including mainland Australia and Madagascar. Coconut crabs also live off the coast of Africa near Zanzibar.
Diogenes pugilator is a species of hermit crab, sometimes called the small hermit crab or south-claw hermit crab. It is found from the coast of Angola to as far north as the North Sea, and eastwards through the Mediterranean Sea, Black Sea and Red Sea. Populations of D. pugilator may be kept in check by the predatory crab Liocarcinus depurator.
Dardanus pedunculatus, the anemone hermit crab, is a species of hermit crab from the Indo-Pacific region. It lives at depths of up to 27 m and collects sea anemones to place on its shell for defence.
Dardanus megistos, the white-spotted hermit crab or spotted hermit crab, is a species of hermit crab belonging to the family Diogenidae.
Vermicularia spirata, common name the West Indian worm-shell or the West Indian wormsnail, is a species of sea snail, a marine gastropod mollusk in the family Turritellidae. Juveniles can move around, but larger individuals become sessile.
Pagurus samuelis, the blueband hermit crab, is a species of hermit crab from the west coast of North America, and the most common hermit crab in California. It is a small species, with distinctive blue bands on its legs. It prefers to live in the shell of the black turban snail, and is a nocturnal scavenger of algae and carrion.
Calcinus tubularis is a species of hermit crab. It is found in the Mediterranean Sea and around islands in the Atlantic Ocean, where it lives below the intertidal zone. Its carapace, eyestalks and claws are marked with numerous red spots. C. tubularis and its sister species, C. verrilli, are the only hermit crabs known to show sexual dimorphism in shell choice, with males using normal marine gastropod shells, while females use shells of gastropods in the family Vermetidae, which are attached to rocks or other hard substrates.
Calcinus verrillii, commonly known as Verrill's hermit crab, is a species of hermit crab in the genus Calcinus which is endemic to Bermuda. It was first described by the American zoologist Mary J. Rathbun and named in honour of the American zoologist Addison Emery Verrill, who spent much time with his students studying the geology and marine fauna of Bermuda.
Diogenes heteropsammicola is a species of hermit crab discovered during samplings between 2012 and 2016 in the shallow waters of the Japanese Amami Islands. This D. heteropsammicola is strongly associated with the walking corals. This hermit crab species is unique due to the discovery that they use living, growing coral as a shell. Crustaceans of this type commonly replace their shell as the organism grows in size, but D. heteropsammicola are the first of their kind to use solitary corals as a shell form. Heteropsammia and Heterocyathus are the two solitary corals that this hermit species has been observed as occupying. These two coral species are also used as a home by symbiotic sipunculans of the genus Aspidosiphon, which normally occupy the corals that the crabs were found inhabiting.
Calcinus laevimanus is a species of hermit crab in the genus Calcinus found in the Indo-West Pacific region, the type locality being Hawaii. It is also known as the blue-eyed hermit crab, zebra hermit crab, dwarf zebra hermit crab, left-handed hermit crab, Hawaiian reef hermit and other similar names.
Calcinus morgani, commonly known as Morgan's hermit crab, is a species of hermit crab in the family Diogenidae found in the Indo-West Pacific region, the type locality being Indonesia.
Dipolydora commensalis is a species of polychaete worm in the family Spionidae. It has a commensal relationship with a hermit crab and occurs on the lower shore of coasts on the western side of the Atlantic Ocean.
Neanthes fucata is a species of marine polychaete worm in the family Nereididae. It lives in association with a hermit crab such as Pagurus bernhardus. It occurs in the northeastern Atlantic Ocean, the North Sea and the Mediterranean Sea.
Dardanus deformis is a species of nocturnal hermit crab that is found in the Indo-Pacific. Its common name is pale anemone hermit. The species is known to transfer sea anemones from one shell to another when it moves to a different shell. It can be kept in an aquarium.
Data related to Calcinus elegans at Wikispecies
Media related to Calcinus elegans at Wikimedia Commons