Juliidae,

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

the bivalved gastropods, is a

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

of minute

sea snail Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the ...

s, marine

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 ...

s or

micromollusk A micromollusk is a shelled mollusk which is extremely small, even at full adult size. The word is usually, but not exclusively, applied to marine mollusks, although in addition, numerous species of land snails and freshwater mollusks also ...

s in the superfamily

Oxynooidea Oxynooidea is a superfamily of small sea snails, bubble snails and bivalved gastropods, marine gastropod mollusks within the superorder Sacoglossa. MolluscaBase eds. (2021). MolluscaBase. Oxynooidea Stoliczka, 1868 (1847). Accessed through: Wor ...

, an opisthobranch group. MolluscaBase eds. (2021). MolluscaBase. Juliidae E. A. Smith, 1885. Accessed through: World Register of Marine Species at: http://marinespecies.org/aphia.php?p=taxdetails&id=196330 on 2021-06-09 Taxonomic edit history These are

sacoglossa Sacoglossa, commonly known as the sacoglossans or the "solar-powered sea slugs", are a superorder of small sea slugs and sea snails, marine gastropod mollusks that belong to the clade Heterobranchia. Sacoglossans live by ingesting the cellular ...

n (sap-sucking) sea snails, and many of them are green in color. These snails are extremely unusual in that their shells consist of two separate hinged pieces or

valves A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fitting ...

. The valves are joined by a ligament, and look nothing like a normal

snail shell The gastropod shell is part of the body of a Gastropoda, gastropod or snail, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical damage, and dehydration, but also serves for muscle attachment and calcium s ...

; instead the valves look almost exactly like the two hinged valves of a

clam Clam is a common name for several kinds of bivalve molluscs. The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds. Clams have two shel ...

, a

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

mollusk, which is a related but very different class of mollusks. Up until the mid-20th century, the Juliidae were known only from

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

shells, and not surprisingly, these fossils were interpreted as being the shells of bivalves. ''

Julia Julia is usually a feminine given name. It is a Latinate feminine form of the name Julio and Julius. (For further details on etymology, see the Wiktionary entry "Julius".) The given name ''Julia'' had been in use throughout Late Antiquity (e.g ...

'', which is the type genus of the family, was named in 1862 by

Augustus Addison Gould Augustus Addison Gould (April 23, 1805 – September 15, 1866) was an American conchologist and malacologist. Biography Born in New Ipswich, New Hampshire, he was the son of music teacher Nathaniel Duren Gould (1781–1864) who was also noted ...

, who described it as a bivalve genus. Juliidae are known from the

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

period to the Recent, but they probably first appeared during the

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...

Taxonomy as "bivalves"

These bivalved gastropods were for a long time only known from

s and dead material. Because of this, they had been described as being somewhat atypical bivalves. In the late 19th century they were classified among the bivalves, within the family

Mytilidae Mytilidae are a family of small to large marine and brackish-water bivalve molluscs in the order Mytilida. One of the genera, '' Limnoperna'', even inhabits freshwater environments. The order has only this one family which contains some 52 gener ...

, the mussels.

George Washington Tryon George Washington Tryon Jr. (20 May 1838 – 5 February 1888) was an American malacologist who worked at the Academy of Natural Sciences in Philadelphia. Biography George Washington Tryon was the son of Edward K. Tryon and Adeline Savidt ...

, Jr. (1884)
''Structural and systematic conchology: an introduction to the study of the Mollusca. Volume III''
Philadelphia, published by the author
page 267
The similarity of the shells of Juliidae to those of bivalves does ''not'' mean that these snails are closely related to bivalves; this is an example of

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...

Discovery of live animals

Until the mid-20th century, these creatures were still considered to be bivalves. Then, in 1959, living individuals of one species were collected on the

green alga The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/Streptophyta. The land plants (Embryophytes) have emerged deep in the Charophyte alga as ...

, ''

Caulerpa ''Caulerpa'' is a genus of seaweeds in the family Caulerpaceae (among the green algae). They are unusual because they consist of only one cell with many nuclei, making them among the biggest single cells in the world. A species in the Mediterran ...

'', in

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

. It was immediately clear that these animals were, in fact, unusual gastropods with a two-part shell. The first-discovered live species of bivalved gastropod was ''

Tamanovalva limax ''Berthelinia'' is a genus of gastropod belonging to the family Juliidae. MolluscaBase eds. (2021). MolluscaBase. Berthelinia Crosse, 1875. Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetail ...

'', described by Kawaguti & Baba (1959). Once the habitat, appearance, and life habits of these very small and inconspicuous animals were understood, researchers in subsequent years were able to find a number of other species and genera in different parts of the world, also living on various species of ''Caulerpa''.

2005 taxonomy

This family is within the superorder

Sacoglossa Sacoglossa, commonly known as the sacoglossans or the "solar-powered sea slugs", are a superorder of small sea slugs and sea snails, marine gastropod mollusks that belong to the clade Heterobranchia. Sacoglossans live by ingesting the cellular ...

(according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). The family Juliidae consists of the following subfamilies (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005): * subfamily Juliinae E. A. Smith, 1885 - synonym: Prasinidae Stoliczka, 1871 * subfamily Bertheliniinae Keen & A. G. Smith, 1961 - synonym: Tamanovalvidae Kawaguti & Baba, 1959 * † (fossil) subfamily Gougerotiinae Le Renard, 1980

Description

As Tryon (1884) wrote in his description of the genus ''

'': the shell is oblong, thick, and cordiform. The valves are closed, the margins entire and the valves are inequilateral. The lunule is deep circular, projecting into the interior of the right

valve A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings ...

, the left valve is in the same place furnished with dentiform tubercles. The hinge line is simple and arched. The

ligament A ligament is the fibrous connective tissue that connects bones to other bones. It is also known as ''articular ligament'', ''articular larua'', ''fibrous ligament'', or ''true ligament''. Other ligaments in the body include the: * Peritoneal li ...

is external and narrow. There are two muscle scars which are unequal and subcentral. These animals have two

, and the soft parts can be completely withdrawn inside the shell. de Bruyne R. H. (2004). ''Encyklopedie ulit a lastur''. Rebo Productions, 336 pp., , page 223. The two valves are usually thin and translucent. In the genus '' Tamanovalva'' there is a protoconch on the

apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics), a teenaged super villainess in the Marvel Universe * Ape-X, a super-intelligent ape in the Squadron Supreme universe *Apex, ...

of the left valve. This is clearly visible in the left valve of '' Tamanovalva babai''. The body of the live animals is in most cases green (as it is in many

ns), and in many species the individual appears green in totality. This, combined with the very small overall size, makes the animal hard to see on the green algae on which it lives. This ability serves as crypsis, especially as cryptic coloration (

camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the ...

). In two specie

an

the camouflage is even more complete: the mantle of the animal is patterned in a way that very closely resembles the structure of the alga on which it lives. The empty valves of the shells of these animals are in some cases green, in other cases brownish-green or yellow, and in yet others, colorless. The species '' Julia zebra'' has shells that are finely striped with brown and blotched with white.

Ecology

Distribution

Species in this family occur in all tropical zone seas and all

temperate zone In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...

seas.

Life cycle

After hatching, the juvenile snails immediately take their place on algae (the larval phase of

veliger A veliger is the planktonic larva of many kinds of sea snails and freshwater snails, as well as most bivalve molluscs (clams) and tusk shells. Description The veliger is the characteristic larva of the gastropod, bivalve and scaphopod ...

is extremely short).

Feeding habits

Juliidae feed on

green algae The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/Streptophyta. The land plants (Embryophytes) have emerged deep in the Charophyte alga as ...

of the genus ''

''. Some species of Juliidae feed only on one species of ''Caulerpa''; others feed on multiple species of this green alga.

Genera

The

type genus In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearing type of a nominal f ...

of the family Juliidae is ''

'' Gould, 1862. Based on a classification by Jensen (1996), three recent genera were recognized in the family Juliidae: ''

'' Gould, 1862; ''Berthelinia'' Crosse, 1875; '' Tamanovalva'' Kawaguti & Baba, 1959. While Jensen (2007)Jensen K. R. (November 2007)
"Biogeography of the Sacoglossa (Mollusca, Opisthobranchia)"
. ''

Bonner zoologische Beiträge The ''Bonn Zoological Bulletin'' (''BzB''), formerly ''Bonner zoologische Beiträge'', is a peer reviewed open access journal dealing with zoology Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is no ...

'' 55(2006)(3-4): 255–281. recognized two recent genera with a few subgenera in the genus ''Berthelinia''. Recent species listed here are based on Jensen (2007), fossil genera and species are based on Le Renard (1996):

Juliinae

* ''

'' Gould, 1862 - synonym: ''Prasina'' Deshayes, 1863 * (fossil) '' Candinia'' Le Renard J., Sabelli B. & Taviani M. 1996Le Renard J., Sabelli B. & Taviani M. (March 1996). "On ''Candinia'' (Sacoglossa: Juliidae), a New Fossil Genus of Bivalved Gastropods". ''

Journal of Paleontology The ''Journal of Paleontology'' is a peer-reviewed scientific journal covering the field of paleontology. It is published by the Paleontological Society. Indexing The ''Journal of Paleontology'' is indexed in: *BIOSIS Previews *Science Citation ...

'' 70(2): 230-235. ** (fossil) '' Candinia pliocaenica'' Le Renard J., Sabelli B. & Taviani M. 1996 - from

lower Pliocene Lower may refer to: *Lower (surname) *Lower Township, New Jersey *Lower Receiver (firearms) *Lower Wick Gloucestershire, England See also *Nizhny Nizhny (russian: Ни́жний; masculine), Nizhnyaya (; feminine), or Nizhneye (russian: Ни́� ...

near

Siena Siena ( , ; lat, Sena Iulia) is a city in Tuscany, Italy. It is the capital of the province of Siena. The city is historically linked to commercial and banking activities, having been a major banking center until the 13th and 14th centuri ...

in Italy. ** (fossil) '' Candinia krachi'' (Baluk & Jakubowski, 1968) - synonym: ''Berthelinia krachi'' Baluk & Jakubowski, 1968

Bertheliniinae

* ''Berthelinia'' Crosse, 1875 - type genus of the subfamily Bertheliniinae ** subgenus ''Berthelinia'' Crosse, 1875 *** (recent) '' Berthelinia caribbea'' Edmunds, 1963Rudman W. B. (4 October 2003)
"''Berthelinia caribbea'' Edmunds, 1963"
. Sea Slug Forum. Australian Museum, Sydney, accessed 10 May 2009. *** (recent) '' Berthelinia chloris'' (Dall, 1918) *** (invalid recent species) ''Berthelinia corallensis'' Hedley, 1920 *** (recent) '' Berthelinia darwini'' Jensen, 1997 *** (recent) '' Berthelinia ganapati'' Sarma, 1975 *** (recent) '' Berthelinia pseudochloris'' Kay, 1964 *** (recent) '' Berthelinia rottnesti'' Jensen, 1993 *** (recent) '' Berthelinia schlumbergeri'' Dautzenberg, 1895 *** (recent) ''

Berthelinia waltairensis ''Berthelinia waltairensis'' is a species of a sea snail with a shell comprising two separate hinged pieces or valves. It is a marine gastropod mollusc in the family Juliidae.Bouchet, P. (2012). Berthelinia waltairensis Sarma, 1975. Accessed thro ...

'' Sarma, 1975 *** (fossil) ''

Berthelinia elegans ''Berthelinia'' is a genus of gastropod belonging to the family Juliidae. MolluscaBase eds. (2021). MolluscaBase. Berthelinia Crosse, 1875. Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails ...

'' Crosse, 1875 ** subgenus '' Midorigai'' : synonym of ''Berthelinia'' Crosse, 1875 *** (recent) '' Berthelinia australis'' (Burn, 1960) - synonym: '' Midorigai australis'' Burn, 1960 ** subgenus '' Tamanovalva'' Kawaguti & Baba, 1959 : synonym of ''Berthelinia'' Crosse, 1875 *** (recent) '' Berthelinia babai'' (Burn, 1965) - synonym: '' Tamanovalva babai'' Burn, 1965 Rudman W. B. (16 October 2011)
"''Tamanovalva babai'' Burn, 1965"
. Sea Slug Forum. Australian Museum, Sydney, accessed 10 May 2009. *** (recent) '' Berthelinia fijiensis'' (Burn, 1966) *** (recent) '' Berthelinia limax'' (Kawaguti & Baba, 1959) - synonym: ''

'' Kawaguti & Baba, 1959 - a type species of the subgenus ''Tamanovalva'' Kawaguti S. & Baba K. (1959). "A preliminary note on a two-valved sacoglossan gastropod, ''Tamanovalva limax'', n. gen., n. sp., from Tamano, Japan". ''Biological Journal Okayama University'' 5(3-4): 177-184. ** subgenus '' Edenttellina'' : synonym of ''Berthelinia'' Crosse, 1875 *** (recent) '' Berthelinia typica'' (Gatliff &

Gabriel In Abrahamic religions (Judaism, Christianity and Islam), Gabriel (); Greek: grc, Γαβριήλ, translit=Gabriḗl, label=none; Latin: ''Gabriel''; Coptic: cop, Ⲅⲁⲃⲣⲓⲏⲗ, translit=Gabriêl, label=none; Amharic: am, ገብር� ...

, 1911) - synonym: '' Edenttellina typica'' Gatliff & Gabriel, 1911Rudman W. B. (16 October 2001)
"''Edenttellina typica'' Gatliff & Gabriel, 1911"
. Sea Slug Forum. Australian Museum, Sydney, accessed 10 May 2009. * (fossil?) '' Anomalomya'' Cossmann, 1887 * (fossil?) '' Namnetia'' Cossmann, 1906 * (fossil?) '' Squamulinia'' Le Renard, 1989

Gougerotiinae

* (fossil) '' Gougerotia'' Le Renard, 1980 - type genus of the subfamily Gougerotiinae ** (fossil) '' Gougerotia orthodonta'' Le Renard, 1980 ? subfamily * (fossil) '' Hemiplicatula'' Deshayes, 1861 * (fossil?) '' Saintia'' de Raincourt, 1877

References

This article incorporates public domain text from reference.

External links

* Cory Pittman & Pauline Fiene. 2009
Juliidae
Sea Slugs of Hawaii.
Images of 4 species of Juliidae in Japan

Photos of ''Julia exquisita''
at Sea Slug Forum
Detailed photos of the shell of ''Julia exquisita''
at Sea Slug Forum * http://taxonomist.symphonic-net.com/contents/Others/Julia/julia!.html {{Taxonbar, from=Q3199382 Extant Eocene first appearances