| Diogenes heteropsammicola | |
|---|---|
 | |
| A, an individual in an aquarium, carrying the coral. B, an individual removed from its host coral. Scale bar: 1 mm. | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Malacostraca |
| Order: | Decapoda |
| Suborder: | Pleocyemata |
| Infraorder: | Anomura |
| Family: | Diogenidae |
| Genus: | Diogenes |
| Species: | D. heteropsammicola |
| Binomial name | |
| Diogenes heteropsammicola Igawa & Kato 2017 [1] | |
Diogenes heteropsammicola is a species of hermit crab discovered during samplings between 2012 and 2016 in the shallow waters of the Japanese Amami Islands. [1] This D. heteropsammicola is strongly associated with the walking corals. [1] This hermit crab species is unique due to the discovery that they use living, growing coral as a shell. They live in inside of the coral and can be distinguished from other types of hermits by their thin chelipeds and leg shape. [1] This species of hermit crab also has a symmetrical abdomen and slender legs to help with living in coral. This is a contrast to how most other hermit crabs look, who usually have asymmetrical bodies. [2] Diogenes heteropsammicola lives inside mobile corals of the genus Heterocyathus and Heteropsammia, a rare example of a hermit crab using a living coral rather than a traditional mollusk shell (Yokoyama et al., 2016). The heteropsammicola carries the host coral across the ocean floors to keep from being buried in sediment. This is similar to the role of the sipunculan worms that once filled the corals themselves. [3] The type of relationship that the hermit crabs have with the shells can be seen as a symbiotic relationship. This prevents the crabs from having to continuously look for new shells as they grow. [4] This unique behavior allows the crab to benefit from the coral’s mobility and protection, while the coral receives cleaning and mobility from the crab.Crustaceans of this type commonly replace their shell as the organism grows in size. This species of hermit crab is the first to use coral as a home. Since it was an unusual change, it gained the attention of marine biologists. [5] Heteropsammia and Heterocyathus are the two solitary corals that this hermit species has been observed as occupying. [6] These two coral species are also used as a home by symbiotic Sipuncula of the genus Aspidosiphon , which normally occupy the corals that were previously occupied by crabs. [1] This relationship is described as a "mutualism shift", where a different species takes over the role of a former symbiotic partner. It is a good example of how relationships can change in response to ecological pressures. [7] This species was discovered and described in 2016 by Japanese researchers studying coral reef ecosystems in southern Japan (Yokoyama et al., 2016). Its discovery challenged prior assumptions about hermit crab behavior and the ecological flexibility of coral symbioses.
The discoverers of this species are Momoko Igawa and Makoto Kato of Kyoto University, Japan. [1] The relationship between Diogenes heteropsammicola and solitary corals is considered an example of mutualism and evolutionary adaptation in symbiotic relationships (Suzuki et al., 2017). It is hypothesized that this behavior may have evolved to help hermit crabs survive in environments where empty shells are scarce.
Diogenes heteropsammicola exhibits unique morphological features that allow it to live in coral cavities, including a slender body and specialized appendages that help anchor it within the coral skeleton (Yokoyama et al., 2016). These traits are uncommon in related hermit crab species.
This species has become a subject of interest in studying symbiosis and environmental adaptation in marine invertebrates. Ongoing research is exploring how environmental changes may impact these unique crab-coral partnerships (Matsuda & Hayashi, 2019).
