''Strubellia paradoxa'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of freshwater

slug Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a smal ...

, a shell-less

freshwater gastropod Freshwater snails are gastropod mollusks which live in fresh water. There are many different families. They are found throughout the world in various habitats, ranging from ephemeral pools to the largest lakes, and from small seeps and springs ...

,Strong E. E., Gargominy O., Ponder W. F. & Bouchet P. (2008). "Global Diversity of Gastropods (Gastropoda; Mollusca) in Freshwater". ''

Hydrobiologia ''Hydrobiologia'', ''The International Journal of Aquatic Sciences'', is a peer-reviewed scientific journal publishing 21 issues per year, for a total of well over 4000 pages per year. ''Hydrobiologia'' publishes original research, reviews and opi ...

'' 595: 149-166. . an aquatic

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

within the

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

Acochlidiacea. ''Strubellia paradoxa'' is one of only two described species in the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

''Strubellia''.

Taxonomy

In 2005, ''Strubellia'' was classified in the family Strubelliidae Rankin, 1979Rankin J. J. (1979). "A freshwater shell-less mollusc from the Caribbean: structure, biotics, and contribution to a new understanding of the Acochlidioidea". ''Life Sciences Contributions,

Royal Ontario Museum The Royal Ontario Museum (ROM) is a museum of art, world culture and natural history in Toronto, Ontario, Canada. It is one of the largest museums in North America and the largest in Canada. It attracts more than one million visitors every year ...

'' 116: 123 pp. within the superfamily

Strubellioidea According to the taxonomy of Bouchet & Rocroi (2005), Strubellioidea was a taxonomic superfamily of sea slugs, mostly marine gastropod mollusks within the informal group Opisthobranchia. However, Schrödl & Neusser (2010)Schrödl M. & Neusser ...

in the taxonomy of Bouchet & Rocroi. According to Schrödl & Neusser (2010)Schrödl M. & Neusser T. P. (2010). "Towards a phylogeny and evolution of Acochlidia (Mollusca: Gastropoda: Opisthobranchia)". ''

Zoological Journal of the Linnean Society The ''Zoological Journal of the Linnean Society'' is a monthly peer-reviewed scientific journal covering zoology published by Oxford University Press on behalf of the Linnean Society. The editor-in-chief is Maarten Christenhusz (Linnean Society). ...

'' 158: 124-154. . ''Strubellia'' is in the family Acochlidiidae.

Distribution

''Strubellia paradoxa'' is known only from Indonesia (

Ambon Island Ambon Island is part of the Maluku Islands of Indonesia. The island has an area of and is mountainous, well watered, and fertile. Ambon Island consists of two territories: the city of Ambon, Maluku, Ambon to the south and various districts ('' ...

). The species ''Strubellia wawrai'' occurs in the

Solomon Islands Solomon Islands is an island country consisting of six major islands and over 900 smaller islands in Oceania, to the east of Papua New Guinea and north-west of Vanuatu. It has a land area of , and a population of approx. 700,000. Its capita ...

Biology

The biology of the genus is comparatively well-known.Brenzinger, B., Neusser, T. P., Jörger, K. M., & Schrödl, M. (2011). “Integrating 3D microanatomy and molecules: natural history of the Pacific freshwater slug ''Strubellia'' Odhner, 1937 (Heterobranchia: Acochlidia), with description of a new species.” ''

Journal of Molluscan Studies The ''Journal of Molluscan Studies'' is the peer-reviewed scientific journal of the Malacological Society of London, covering research in malacology.

'' 77(4): 351-374. ''Strubellia'' species are reddish-brown, slender slugs of 5 to 40 mm length. They live under rocks in streams and creeks on volcanic islands and feed on the contents of calcareous egg capsules of other, herbivorous, snails (family

Neritidae Neritidae, common name the nerites, is a taxonomic family of small to medium-sized saltwater and freshwater snails which have a gill and a distinctive operculum. MolluscaBase eds. (2021). MolluscaBase. Neritininae Poey, 1852. Accessed through: ...

) occurring in the same habitat. Their

radula The radula (, ; plural radulae or radulas) is an anatomical structure used by molluscs for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food ...

is modified for slowly piercing these capsules with a sharp, saw-like central teeth of which some are worn down during the process. Calcareous spicules embedded below the skin help to stabilize the head during feeding; the nutritive contents of the capsules are slowly sucked out. The kidney and heart of ''Strubellia'' and other Acochlidiidae are enlarged compared to otherwise marine Acochlidiacea; this is thought to be an adaptation to the osmotic stresses of life in freshwater. ''Strubellia'' species are unusual among slugs in being

sequential hermaphrodites Sequential hermaphroditism (called dichogamy in botany) is a type of hermaphroditism that occurs in many fish, gastropods, and plants. Sequential hermaphroditism occurs when the individual changes its sex at some point in its life. In particular, ...

, they become mature as males and later turn into females after copulation (protandry); this involves reorganization of the reproductive organs including loss of the elaborate copulatory organ. ''Strubellia'', and other Acochlidiidae, are thought to have an

amphidromous Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousan ...

life cycle: they spawn in freshwater; their swimming veliger larvae are then swept downstream into the river’s mouth or sea where they undergo

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

snails. It is not known how and when larvae or juveniles do this and recolonize their freshwater habitat; it has been suggested that this may even happen by larger, more mobile

dispersal vector A dispersal vector is an agent of biological dispersal that moves a dispersal unit, or organism, away from its birth population to another location or population in which the individual will reproduce. These dispersal units can range from pollen t ...

Taxonomy

Distribution

Biology

References

Further reading