Juliidae
Encyclopedia
Juliidae, common name
the bivalved gastropods, is a family
of minute sea snail
s, marine
gastropod mollusks or micromollusk
s in the superfamily Oxynooidea
, an opisthobranch group.
This family of snails is extremely unusual in that their shells consist of two separate hinged pieces or valves, which are joined by a ligament, and which look nothing like a normal snail shell
, but instead look almost exactly like the two hinged valves of a clam
, a bivalve mollusk, a very different class of animals.
In the past the Juliidae were known only from fossil
shells, and not surprisingly these fossils were therefore interpreted as being the shells of bivalves. Julia
, which is the type genus of the family, was named in 1862 by Augustus Addison Gould
, who described it as a bivalve genus. Julliidae are known from the Eocene
period to the Recent, but they probably first appeared during the Paleocene
.
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
, the true mussels.
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
.
, in Japan
. It was immediately clearly visible that these animals are in fact unusual gastropods with a two-part shell. The first discovered live species of bivalved gastropod was Tamanovalva limax, described by Kawaguti & Baba
(1959).
Once the habitat, appearance, and life habits of these very small and inconspicuous animals were understood, in subsequent years researchers were able to find a number of other species and other genera in different parts of the world, also living on various species of Caulerpa.
(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
):
As Tryon (1884) wrote in his description of the genus Julia
: 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, the left valve is in the same place furnished with dentiform tubercles. The hinge line is simple and arched. The ligament
is external and narrow. There are two muscle scars which are unequal and subcentral.
These animals have two valves, and the soft parts can be completely withdrawn inside the shell. The two valves are usually thin and translucent.
In the genus Tamanovalva there is a protoconch
on the 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 sacoglossa
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
). In two species http://www.seaslugforum.net/factsheet.cfm?base=midoaust and http://www.seaslugforum.net/factsheet.cfm?base=edentypi 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. http://seaslugsofhawaii.com/species/Julia-zebra-b.html
and all temperate zone seas.
is extremely short).
of the genus Caulerpa
. Some species of Juliidae feed only on one species of Caulerpa, others in the family feed on more than one species of this green alga.
of the family Juliidae is Julia
Gould, 1862.
Based on a classification by Jensen (1996), three recent genera were recognized in the family Juliidae: Julia
Gould, 1862; Berthelinia Crosse, 1875; Tamanovalva Kawaguti & Baba, 1959.
While Jensen (2007) 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):
? subfamily
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
the bivalved gastropods, is a family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of minute sea snail
Sea snail
Sea snail is a common name for those snails that normally live in saltwater, marine gastropod molluscs....
s, marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
gastropod mollusks or micromollusk
Micromollusk
A micromollusk is a descriptive term for 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 reach adult size at very small...
s in the superfamily Oxynooidea
Oxynooidea
Oxynooidea is a superfamily of small sea snails, bubble snails and bivalved gastropods, marine gastropod mollusks within the clade Sacoglossa.Oxynooidea is the only superfamily in the clade Oxynoacea.-Taxonomy:* clade Oxynoacea...
, an opisthobranch group.
This family of snails is extremely unusual in that their shells consist of two separate hinged pieces or valves, which are joined by a ligament, and which look nothing like a normal snail shell
Gastropod shell
The gastropod shell is a shell which is part of the body of a gastropod or snail, one kind of mollusc. The gastropod shell is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage...
, but instead look almost exactly like the two hinged valves of a clam
Clam
The word "clam" can be applied to freshwater mussels, and other freshwater bivalves, as well as marine bivalves.In the United States, "clam" can be used in several different ways: one, as a general term covering all bivalve molluscs...
, a bivalve mollusk, a very different class of animals.
In the past the Juliidae were known only from fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
shells, and not surprisingly these fossils were therefore interpreted as being the shells of bivalves. Julia
Julia (gastropod)
Julia is a minute sea snails genus, marine gastropod mollusks or micromollusks in the superfamily Oxynooidea.Julia is the type genus of the family Juliidae.-Description:...
, which is the type genus of the family, was named in 1862 by Augustus Addison Gould
Augustus Addison Gould
Augustus Addison Gould was an American conchologist and malacologist.-Biography:...
, who described it as a bivalve genus. Julliidae are known from the Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
period to the Recent, but they probably first appeared during the Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
.
Taxonomy as "bivalves"
These bivalved gastropods were for a long time only known from fossilFossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
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
Mytilidae is a family of small to large saltwater mussels, marine bivalve mollusks in the order Mytiloida. It is the only family in the order...
, the true mussels.
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
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
.
Discovery of live animals
Up until the mid 20th century, these creatures were still considered to be bivalves. Then finally in 1959, living individuals of one species were collected on the green alga, CaulerpaCaulerpa
Caulerpa is a genus of seaweeds in the family Caulerpaceae . They are unusual because they consist of only one cell with many nuclei, making them among the biggest single cells in the world...
, in Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. It was immediately clearly visible that these animals are in fact unusual gastropods with a two-part shell. The first discovered live species of bivalved gastropod was Tamanovalva limax, described by Kawaguti & Baba
Kikutaro Baba
was a Japanese malacologist. He was the leading researcher on sea slugs and bubble snails, opisthobranch gastropod mollusks in Japan.- Biography :* 1932-1941 Kyushu University* 1948-1949 Osaka Kyoiku University* 1976 - Order of the Rising Sun...
(1959).
Once the habitat, appearance, and life habits of these very small and inconspicuous animals were understood, in subsequent years researchers were able to find a number of other species and other genera in different parts of the world, also living on various species of Caulerpa.
2005 taxonomy
This family is within the clade SacoglossaSacoglossa
Sacoglossa, commonly known as the sacoglossans or the "sap-sucking sea slugs", are a clade of small sea slugs and sea snails, marine gastropod mollusks that belong to the clade Heterobranchia...
(according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005
Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005)
The taxonomy of the Gastropoda as it was revised by Philippe Bouchet and Jean-Pierre Rocroi is currently the most up-to-date overall system for classifying gastropod mollusks...
).
The family Juliidae consists of the following subfamilies (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005
Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005)
The taxonomy of the Gastropoda as it was revised by Philippe Bouchet and Jean-Pierre Rocroi is currently the most up-to-date overall system for classifying gastropod mollusks...
):
- 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
Julia (gastropod)
Julia is a minute sea snails genus, marine gastropod mollusks or micromollusks in the superfamily Oxynooidea.Julia is the type genus of the family Juliidae.-Description:...
: 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, the left valve is in the same place furnished with dentiform tubercles. The hinge line is simple and arched. The ligament
Ligament
In anatomy, the term ligament is used to denote any of three types of structures. Most commonly, it refers to fibrous tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament.Ligament can also refer to:* Peritoneal...
is external and narrow. There are two muscle scars which are unequal and subcentral.
These animals have two valves, and the soft parts can be completely withdrawn inside the shell. The two valves are usually thin and translucent.
In the genus Tamanovalva there is a protoconch
Protoconch
A protoconch is an embryonic or larval shell of some classes of molluscs, e.g., the initial chamber of an ammonite or the larval shell of a gastropod...
on the apex
Apex (mollusc)
Apex is an anatomical term for the tip of the mollusc shell of a gastropod, scaphopod, or cephalopod mollusc.-Gastropods:The word "apex" is most often used to mean the tip of the spire of the shell of a gastropod...
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 sacoglossa
Sacoglossa
Sacoglossa, commonly known as the sacoglossans or the "sap-sucking sea slugs", are a clade of small sea slugs and sea snails, marine gastropod mollusks that belong to the clade Heterobranchia...
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
Crypsis
In ecology, crypsis is the ability of an organism to avoid observation or detection by other organisms. It may be either a predation strategy or an antipredator adaptation, and methods include camouflage, nocturnality, subterranean lifestyle, transparency, and mimicry...
, especially as cryptic coloration (camouflage
Camouflage
Camouflage is a method of concealment that allows an otherwise visible animal, military vehicle, or other object to remain unnoticed, by blending with its environment. Examples include a leopard's spotted coat, the battledress of a modern soldier and a leaf-mimic butterfly...
). In two species http://www.seaslugforum.net/factsheet.cfm?base=midoaust and http://www.seaslugforum.net/factsheet.cfm?base=edentypi 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
Julia zebra
Julia zebra is a species of a sea snail with a shell comprising two separate hinged pieces or valves. It is a marine gastropod mollusk in the family Juliidae.-Distribution:The type locality for this species is Yamaguchi Prefecture, Japan....
has shells that are finely striped with brown and blotched with white. http://seaslugsofhawaii.com/species/Julia-zebra-b.html
Distribution
Species in this family occur in all tropical zone seasTropical marine ecosystem
Islands and coastal areas 10° to 20° north or south of the equator usually have a tropical marine climate.The ocean is the main influence in creating the tropical marine system climate....
and all temperate zone seas.
Life cycle
After hatching out from eggs, the juvenile snails immediately take their place on algae (the larval phase of veligerVeliger
A veliger is the planktonic larva of many kinds of marine and freshwater gastropod molluscs, as well as most bivalve mollusks.- Description :...
is extremely short).
Feeding habits
Juliidae feed on green algaeGreen algae
The green algae are the large group of algae from which the embryophytes emerged. As such, they form a paraphyletic group, although the group including both green algae and embryophytes is monophyletic...
of the genus Caulerpa
Caulerpa
Caulerpa is a genus of seaweeds in the family Caulerpaceae . They are unusual because they consist of only one cell with many nuclei, making them among the biggest single cells in the world...
. Some species of Juliidae feed only on one species of Caulerpa, others in the family feed on more than one species of this green alga.
Genera
The type genusType genus
In biological classification, a type genus is a representative genus, as with regard to a biological family. The term and concept is used much more often and much more formally in zoology than it is in botany, and the definition is dependent on the nomenclatural Code that applies:* In zoological...
of the family Juliidae is Julia
Julia (gastropod)
Julia is a minute sea snails genus, marine gastropod mollusks or micromollusks in the superfamily Oxynooidea.Julia is the type genus of the family Juliidae.-Description:...
Gould, 1862.
Based on a classification by Jensen (1996), three recent genera were recognized in the family Juliidae: Julia
Julia (gastropod)
Julia is a minute sea snails genus, marine gastropod mollusks or micromollusks in the superfamily Oxynooidea.Julia is the type genus of the family Juliidae.-Description:...
Gould, 1862; Berthelinia Crosse, 1875; Tamanovalva Kawaguti & Baba, 1959.
While Jensen (2007) 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
- JuliaJulia (gastropod)Julia is a minute sea snails genus, marine gastropod mollusks or micromollusks in the superfamily Oxynooidea.Julia is the type genus of the family Juliidae.-Description:...
Gould, 1862 - synonym: Prasina Deshayes, 1863 - (fossil) Candinia Le Renard J., Sabelli B. & Taviani M. 1996
- (fossil) Candinia pliocaenica Le Renard J., Sabelli B. & Taviani M. 1996 - from lower Pliocene near SienaSienaSiena is a city in Tuscany, Italy. It is the capital of the province of Siena.The historic centre of Siena has been declared by UNESCO a World Heritage Site. It is one of the nation's most visited tourist attractions, with over 163,000 international arrivals in 2008...
in Italy. - (fossil) Candinia krachi (Baluk & Jakubowski, 1968) - synonym: Berthelinia krachi Baluk & Jakubowski, 1968
- (fossil) Candinia pliocaenica Le Renard J., Sabelli B. & Taviani M. 1996 - from lower Pliocene near Siena
Bertheliniinae
- Berthelinia Crosse, 1875 - type genus of the subfamily Bertheliniinae
-
- subgenus Berthelinia Crosse, 1875
- (recent) Berthelinia caribbeaBerthelinia caribbeaBerthelinia caribbea is a species of a sea snail with a shell comprising two separate hinged pieces or valves. It is a marine gastropod mollusk in the family Juliidae.-Distribution:The type locality for this species is Port Royal, Jamaica....
Edmunds, 1963 - (recent) Berthelinia chlorisBerthelinia chlorisBerthelinia chloris, also known as the Green sapsucker, is a species of a sea snail with a shell comprising two separate hinged pieces or valves. It is a marine gastropod mollusk in the family Juliidae.-Distribution:...
(Dall, 1918) - (invalid recent species) Berthelinia corallensis Hedley, 1920
- (recent) Berthelinia darwiniBerthelinia darwiniBerthelinia darwini is a species of a sea snail with a shell comprising two separate hinged pieces or valves. It is a marine gastropod mollusk in the family Juliidae.-Distribution:This species is found in Darwin, Northern Territory, Australia....
Jensen, 1997 - (recent) Berthelinia ganapatiBerthelinia ganapatiBerthelinia ganapati is a species of a sea snail with a shell comprising two separate hinged pieces or valves. It is a marine gastropod mollusk in the family Juliidae.-Distribution:The type locality for this species is Southeastern India....
Sarma, 1975 - (recent) Berthelinia pseudochlorisBerthelinia pseudochlorisBerthelinia pseudochloris is a species of a sea snail with a shell comprising two separate hinged pieces or valves. It is a marine gastropod mollusk in the family Juliidae.-Distribution:The type locality for this species is Kauai, Hawaii....
Kay, 1964 - (recent) Berthelinia rottnestiBerthelinia rottnestiBerthelinia rottnesti is a species of a sea snail with a shell comprising two separate hinged pieces or valves. It is a marine gastropod mollusk in the family Juliidae.-Distribution:...
Jensen, 1993 - (recent) Berthelinia schlumbergeriBerthelinia schlumbergeriBerthelinia schlumbergeri is a species of a sea snail with a shell comprising two separate hinged pieces or valves. It is a marine gastropod mollusk in the family Juliidae.-Distribution:...
Dautzenberg, 1895 - (recent) Berthelinia waltairensisBerthelinia waltairensisBerthelinia waltairensis is a species of a sea snail with a shell comprising two separate hinged pieces or valves. It is a marine gastropod mollusk in the family Juliidae.-Distribution:The type locality for this species is Southeastern India....
Sarma, 1975 - (fossil) Berthelinia elegans Crosse, 1875
- (recent) Berthelinia caribbea
- subgenus Midorigai : synonym of Berthelinia Crosse, 1875
- (recent) Berthelinia australisBerthelinia australisBerthelinia australis is a species of a sea snail with a shell comprising two separate hinged pieces or valves. It is a marine gastropod mollusk in the family Juliidae.-Distribution:The type locality for this species is Torquay, Victoria, Australia....
(Burn, 1960) - synonym: Midorigai australis Burn, 1960
- (recent) Berthelinia australis
- subgenus Tamanovalva Kawaguti & Baba, 1959 : synonym of Berthelinia Crosse, 1875
- (recent) Berthelinia babaiBerthelinia babaiBerthelinia babai is a species of a sea snail with a shell comprising two separate hinged pieces or valves. It is a marine gastropod mollusk in the family Juliidae.-Distribution:The type locality for this species is Torquay, Victoria, Australia....
(Burn, 1965) - synonym: Tamanovalva babai Burn, 1965 - (recent) Berthelinia fijiensisBerthelinia fijiensisBerthelinia fijiensis is a species of a sea snail with a shell comprising two separate hinged pieces or valves. It is a marine gastropod mollusk in the family Juliidae....
(Burn, 1966) - (recent) Berthelinia limaxBerthelinia limaxBerthelinia limax is a species of a sea snail with a shell comprising two separate hinged pieces or valves. It is a marine gastropod mollusk in the family Juliidae.-Distribution:The type locality for this species is Seto, Aichi, Japan....
(Kawaguti & Baba, 1959) - synonym: Tamanovalva limax Kawaguti & Baba, 1959 - a type species of the subgenus Tamanovalva
- (recent) Berthelinia babai
- subgenus Edenttellina : synonym of Berthelinia Crosse, 1875
- (recent) Berthelinia typicaBerthelinia typicaBerthelinia typica is a species of a sea snail with a shell comprising two separate hinged pieces or valves. It is a marine gastropod mollusk in the family Juliidae.-Distribution:The type locality for this species is Port Phillip, Victoria, Australia....
(Gatliff & Gabriel, 1911) - synonym: Edenttellina typica Gatliff & Gabriel, 1911
- (recent) Berthelinia typica
- subgenus Berthelinia Crosse, 1875
- (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
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