Cephalaspidea
Encyclopedia
The suborder Cephalaspidea, also known as the headshield slugs and bubble snails, is a clade
of sea slugs and bubble snails, marine
gastropod mollusks within the larger clade Euopisthobranchia
.. Bubble shells is another common name for these families of marine gastropods, some of which have thin bubble-like shells.
Members of this worldwide clade appear to be the most primitive of the opisthobranchs.
Headshield slugs are the most morphologically diverse group of all the opisthobranchs.
to detect prey, which may be other opisthobranchs, polychaetes or bristleworms and foraminifera
ns. Several species are voracious carnivores.
Members of the brightly colored genus Chelidonura
also have well-developed eyes on the anterior end of the head and bundles of sensory cilia around the mouth. With these cilia they are able to track their prey by following the victim’s mucous trail.
The Hancock's organ
is a chemosensory organ
situated between the foot and the headshield. It plays a role in olfactory and sensory detection. It is visible as a dark brown pit at the base of the right rhinophore
.
(2005), the clade
Cephalaspidea is arranged as follows:
The superfamily Acteonoidea
has been included into the new Informal Group "Lower Heterobranchia" and the superfamily Cylindrobulloidea becomes part of the Group Cylindrobullida.
The taxonomy of Cephalaspidea sensu lato by Malaquias et al. (2009) is arranged as follows (there are listed genera under molecular analysis; not analyzed families are under "incertae sedis
"):
Architectibranchia
Haszprunar, 1985
Runcinacea Burn, 1963
Cephalaspidea Fischer, 1887 - This means Cephalaspidea sensu stricto
(formerly the only member of Bullactidae) into the family Haminoeidae
.
Jörger et al. (2010) moved Cephalaspidea sensu stricto and Runcinacea into the Euopisthobranchia
and they confirmed the placement of Acteonoidea
within the Lower Heterobranchia
. All families of Architectibranchia were already within the Lower Heterobranchia in the taxonomy of Bouchet & Rocroi, except for the Notodiaphanidae
, which has been placed in the Lower Heterobranchia since 2010, in order that the Architectibranchia can be considered to be monophyletic.
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
of sea slugs and bubble snails, 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 within the larger clade Euopisthobranchia
Euopisthobranchia
Euopisthobranchia is a taxonomic clade of snails and slugs in the clade Heterobranchia within the clade Euthyneura.Euopisthobranchia was established as a new taxon by Jörger et al...
.. Bubble shells is another common name for these families of marine gastropods, some of which have thin bubble-like shells.
Members of this worldwide clade appear to be the most primitive of the opisthobranchs.
Headshield slugs are the most morphologically diverse group of all the opisthobranchs.
Anatomy
The vast majority possess a shell, although it may be reduced or internal. They have a well-developed headshield, a characteristic broadening at the head, which is used to plow beneath the surface of the sand. This headshield prevents the sand entering the mantle cavity. There is a muscular foot with or without parapodia (fleshy wing-like flaps).Life habits and related anatomical structures
Headshield slugs often live just beneath the surface of the sand and can also be seen crawling on rocks. They have well-developed sensory structuresSensory organs of gastropods
Sensory organs of gastropods include olfactory organs, eyes, statocysts and mechanoreceptors. Gastropods have no sense of hearing.- Olfactory organs :...
to detect prey, which may be other opisthobranchs, polychaetes or bristleworms and foraminifera
Foraminifera
The Foraminifera , or forams for short, are a large group of amoeboid protists which are among the commonest plankton species. They have reticulating pseudopods, fine strands of cytoplasm that branch and merge to form a dynamic net...
ns. Several species are voracious carnivores.
Members of the brightly colored genus Chelidonura
Chelidonura
Chelidonura is a genus of small, sometimes colorful, sea slugs. These are headshield slugs or cephalaspideans, marine opisthobranch gastropod mollusks in the family Aglajidae...
also have well-developed eyes on the anterior end of the head and bundles of sensory cilia around the mouth. With these cilia they are able to track their prey by following the victim’s mucous trail.
The Hancock's organ
Hancock's organ
Hancock's organ is a lateral sensory organ of gastropods, a sense organ found in some sea snails. This organ is found in most shelled opisthobranchs....
is a chemosensory organ
Sensory organs of gastropods
Sensory organs of gastropods include olfactory organs, eyes, statocysts and mechanoreceptors. Gastropods have no sense of hearing.- Olfactory organs :...
situated between the foot and the headshield. It plays a role in olfactory and sensory detection. It is visible as a dark brown pit at the base of the right rhinophore
Rhinophore
A rhinophore is one of a pair of club-shaped structures which are the most prominent part of the external head anatomy of a group of sea slugs, marine gastropod opisthobranch mollusks in the order Nudibranchia, the nudibranchs, specifically the dorid nudibranchs.- Etymology :The name relates to the...
.
Taxonomy
The taxonomy of the shelled cephalaspideans, the bubble snails, like that of many shelled mollusks, used to be based very simply on shell characteristics. But because there are some similarities in shell morphology throughout this group, more recently taxonomists have taken other anatomical characteristics into consideration, such as the radula, gizzard, penis, and Hancock’s organ.Linnaean taxonomy
- Suborder Cephalaspidea P. Fischer, 1883
- Superfamily ActeonoideaActeonoideaActeonoidea is a superfamily of sea snails, or bubble snails, marine gastropod mollusks.- Taxonomy :In the taxonomy of Bouchet & Rocroi , the superfamily Acteonoidea has been included into the informal group "Lower Heterobranchia" , also known as the Allogastropoda.Only one of analyses by Jörger...
D'OrbignyAlcide d'OrbignyAlcide Charles Victor Marie Dessalines d'Orbigny was a French naturalist who made major contributions in many areas, including zoology , palaeontology, geology, archaeology and anthropology....
, 1835 - Superfamily BulloideaBulloideaBulla is a genus of medium to large hermaphrodite sea snails, shelled marine opisthobranch gastropod molluscs. These herbivorous snails are in the suborder Cephalaspidea, headshield slugs, and the order Opisthobranchia...
LamarckJean-Baptiste LamarckJean-Baptiste Pierre Antoine de Monet, Chevalier de la Marck , often known simply as Lamarck, was a French naturalist...
, 1801 - Superfamily Cylindrobulloidea ThieleJohannes ThieleJohannes Thiele, full name Karl Hermann Johannes Thiele was a German zoologist specialized in malacology. His Handbuch der systematischen Weichtierkunde is a standard work...
, 1931 - These are now included in the suborder SacoglossaSacoglossaSacoglossa, 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... - Superfamily DiaphanoideaDiaphanoideaDiaphanoidea is a taxonomic superfamily of small sea snails, marine opisthobranch gastropod mollusks or micromollusks in the Cephalaspidea, the headshield slugs and bubble snails....
Odhner, 1914 - Superfamily HaminoeoideaHaminoeoideaHaminoeoidea is a taxonomic superfamily of small sea snails or bubble shells, marine opisthobranch gastropod mollusks in the clade Cephalaspidea, the headshield slugs and bubble snails....
Pilsbry, 1895 - Superfamily PhilinoideaPhilinoideaPhilinoidea is a taxonomic superfamily of sea slugs, specifically headshield slugs, marine gastropod mollusks in the clade Cephalaspidea.-Anatomy:They are generally small animals, and have no shell or gills...
J.E. GrayJohn Edward GrayJohn Edward Gray, FRS was a British zoologist. He was the elder brother of George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray ....
, 1850 - Superfamily Ringiculoidea Philippi, 1853
- Superfamily Acteonoidea
2005 taxonomy
In the taxonomy of Bouchet & RocroiTaxonomy 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...
(2005), the clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
Cephalaspidea is arranged as follows:
- Superfamily BulloideaBulloideaBulla is a genus of medium to large hermaphrodite sea snails, shelled marine opisthobranch gastropod molluscs. These herbivorous snails are in the suborder Cephalaspidea, headshield slugs, and the order Opisthobranchia...
: family Bullidae - Superfamily DiaphanoideaDiaphanoideaDiaphanoidea is a taxonomic superfamily of small sea snails, marine opisthobranch gastropod mollusks or micromollusks in the Cephalaspidea, the headshield slugs and bubble snails....
: families DiaphanidaeDiaphanidaeDiaphanidae is a taxonomic family of small sea snails, marine opisthobranch gastropod molluscs or micromollusks in the superfamily Diaphanoidea, the headshield slugs and bubble snails....
and NotodiaphanidaeNotodiaphanidaeNotodiaphana fragilis is a species of marine snail, gastropod mollusk in the clade Architectibranchia.Notodiaphana fragilis is the only species in the genus Notodiaphana...
, - Superfamily HaminoeoideaHaminoeoideaHaminoeoidea is a taxonomic superfamily of small sea snails or bubble shells, marine opisthobranch gastropod mollusks in the clade Cephalaspidea, the headshield slugs and bubble snails....
: families HaminoeidaeHaminoeidaeHaminoeidae, commonly known as the haminoeid bubble snail family, is a taxonomic family of sea snails, marine opisthobranch gastropod mollusks in the superfamily Haminoeoidea....
, Bullactidae and Smaragdinellidae - Superfamily PhilinoideaPhilinoideaPhilinoidea is a taxonomic superfamily of sea slugs, specifically headshield slugs, marine gastropod mollusks in the clade Cephalaspidea.-Anatomy:They are generally small animals, and have no shell or gills...
: families PhilinidaePhilinidaePhilinidae is a family of medium-sized, sea slugs, marine opisthobranch gastropod mollusks. They are headshield slugs, in the Cephalaspidea.-Genera:Genera within the family Philinidae include:* Johania Monterosato, 1884* Laona A. Adams, 1865...
, AglajidaeAglajidaeAglajidae is a family of often colorful, medium-sized, sea slugs, marine opisthobranch gastropod mollusks. These are not nudibranchs; instead they are headshield slugs, in the clade Cephalaspidea.-Genera:...
, CylichnidaeCylichnidaeCylichnidae, common name the "chalice bubble snails" or "canoe bubble snails" is a family of sea snails or bubble snails, marine gastropod mollusks in the superfamily Philinoidea.- 2005 taxonomy :...
, GastropteridaeGastropteridaeGastropteridae is a family of sea slugs, gastropod mollusks in the superfamily Philinoidea of the clade Cephalaspidea, the headshield slugs and bubble snails....
, PhilinoglossidaePhilinoglossidaePhilinoglossidae is a family of marine snails, gastropod mollusks in the superfamily Philinoidea.- Genera :* Philinoglossa Hertling, 1932** Philinoglossa helgolandica Hertling, 1932** Philinoglossa remanei Marcus & Marcus, 1958...
, PlusculidaePlusculidaePluscula cuica is a species of marine snail, gastropod mollusk in the superfamily Philinoidea within the clade Cephalaspidea.Pluscula cuica is the only species in the genus Pluscula. Genus Pluscula is the only genus in the family Plusculidae....
and RetusidaeRetusidaeRetusidae is a family of small sea snails, marine opisthobranch gastropod mollusks. They are headshield slugs, in the clade Cephalaspidea.-Genera:Genera within the family Retusidae include:* Coleophysis* Cylichnina Monterosato, 1884... - Superfamily RuncinoideaRuncinoideaRuncinoidea is a taxonomic superfamily or a clade Runcinaecea Runcinoidea is a taxonomic superfamily (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005) or a clade Runcinaecea Runcinoidea is a taxonomic superfamily (according to the taxonomy of the Gastropoda by Bouchet &...
: families RuncinidaeRuncinidaeRuncinidae is a family of medium-sized, sea slugs, marine opisthobranch gastropod mollusks. They are headshield slugs, in the clade Cephalaspidea ....
and IlbiidaeIlbiidaeIlbiidae is a family of marine opisthobranch gastropod mollusks in the clade Cephalaspidea ....
The superfamily Acteonoidea
Acteonoidea
Acteonoidea is a superfamily of sea snails, or bubble snails, marine gastropod mollusks.- Taxonomy :In the taxonomy of Bouchet & Rocroi , the superfamily Acteonoidea has been included into the informal group "Lower Heterobranchia" , also known as the Allogastropoda.Only one of analyses by Jörger...
has been included into the new Informal Group "Lower Heterobranchia" and the superfamily Cylindrobulloidea becomes part of the Group Cylindrobullida.
2009 taxonomy
Malaquias et al. (2009) have rearranged taxonomy of Cephalaspidea sensu lato:- reinstated ArchitectibranchiaArchitectibranchiaArchitectibranchia is a clade of marine snails, gastropod mollusks.It has been originally established containing the superfamilies Acteonoidea, Ringiculoidea, and Diaphanoidea.- 2005 taxonomy :...
- reinstated Runcinacea as a valid name outside Cephalaspidea.
- reinstated ScaphandridaeScaphandridaeScaphandridae is a family of sea snails, marine gastropod mollusks in the superfamily ???.- Taxonomy :Scaphandridae was considered as a synonym of Cylichnidae in the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005).However, Malaquias et al...
as a valid family. - they did not use superfamilies in the classification scheme.
The taxonomy of Cephalaspidea sensu lato by Malaquias et al. (2009) is arranged as follows (there are listed genera under molecular analysis; not analyzed families are under "incertae sedis
Incertae sedis
, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
"):
Architectibranchia
Architectibranchia
Architectibranchia is a clade of marine snails, gastropod mollusks.It has been originally established containing the superfamilies Acteonoidea, Ringiculoidea, and Diaphanoidea.- 2005 taxonomy :...
Haszprunar, 1985
- Family ActeonidaeActeonidaeActeonidae, common name the "barrel bubble snails", is a family of small sea snails, marine gastropod mollusks of the informal group Lower Heterobranchia.-Shell description:The shell is usually smaller than 25 mm...
d’Orbigny, 1843 - Acteon, Mexacteon, PupaPupa (gastropod)Pupa is a genus of small sea snail, a marine gastropod mollusc in the family Acteonidae.The genus is named Pupa because the shell of these snails resemble an insect pupa in overall shape.... - Family Aplustridae Gray, 1847 - HydatinaHydatinaHydatina is a genus of a sea snails, bubble snails, marine opisthobranch gastropod mollusks in the family Aplustridae.- Species :Species within this genus include:* Hydatina albocincta Van der Hoeven, 1839...
, MicromeloMicromeloMicromelo is a genus of sea snails, bubble snails, marine opisthobranch gastropod mollusks in the family Aplustridae.- Species :Species within the genus Micromelo include:* Micromelo guamensis* Micromelo undata... - Family BullinidaeBullinidaeBullinidae is a taxonomic family of small sea snails or bubble snails, marine gastropod mollusks in the superfamily Acteonoidea.Synonyms for this family are Nonacteoninidae Bandel, 1994 and Sulcoactaeonidae Gründel, 1997....
Gray, 1850 incertae sedis - Family RingiculidaeRingiculidaeRingiculidae are a family of minute deep water sea snails or micromolluscs, marine gastropod mollusks or micromollusks in the informal group Lower Heterobranchia.Ringiculidae is the only family within the superfamily Ringiculoidea....
Philippi, 1853 incertae sedis - Family NotodiaphanidaeNotodiaphanidaeNotodiaphana fragilis is a species of marine snail, gastropod mollusk in the clade Architectibranchia.Notodiaphana fragilis is the only species in the genus Notodiaphana...
Thiele, 1931 incertae sedis
Runcinacea Burn, 1963
- Family RuncinidaeRuncinidaeRuncinidae is a family of medium-sized, sea slugs, marine opisthobranch gastropod mollusks. They are headshield slugs, in the clade Cephalaspidea ....
H. Adams & A. Adams, 1854 - Runcina - Family IlbiidaeIlbiidaeIlbiidae is a family of marine opisthobranch gastropod mollusks in the clade Cephalaspidea ....
Burn, 1963 incertae sedis
Cephalaspidea Fischer, 1887 - This means Cephalaspidea sensu stricto
- Family DiaphanidaeDiaphanidaeDiaphanidae is a taxonomic family of small sea snails, marine opisthobranch gastropod molluscs or micromollusks in the superfamily Diaphanoidea, the headshield slugs and bubble snails....
Odhner, 1914 - Diaphana, genus Colpodaspis is incertae sedis - Family CylichnidaeCylichnidaeCylichnidae, common name the "chalice bubble snails" or "canoe bubble snails" is a family of sea snails or bubble snails, marine gastropod mollusks in the superfamily Philinoidea.- 2005 taxonomy :...
H. Adams & A. Adams, 1854 - CylichnaCylichnaCylichna is a genus of sea snails or bubble snails, marine gastropod molluscs in the family Cylichnidae, the "chalice bubble snails". -Species:Species within the genus Cylichna include:* Cylichna aethiopica* Cylichna affinis... - Family ScaphandridaeScaphandridaeScaphandridae is a family of sea snails, marine gastropod mollusks in the superfamily ???.- Taxonomy :Scaphandridae was considered as a synonym of Cylichnidae in the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005).However, Malaquias et al...
G. O Sars, 1878 - ScaphanderScaphanderScaphander is a genus of sea snails, marine gastropod molluscs in the family Scaphandridae, the canoe bubbles.-Species:Species within the genus Scaphander include:* Scaphander alatus: synonym of Scaphander mundus Watson, 1883... - Family RetusidaeRetusidaeRetusidae is a family of small sea snails, marine opisthobranch gastropod mollusks. They are headshield slugs, in the clade Cephalaspidea.-Genera:Genera within the family Retusidae include:* Coleophysis* Cylichnina Monterosato, 1884...
Thiele, 1925 - Retusa, Pyrunculus - Family Rhizoridae Dell, 1952 - Volvulella
- Family Bullidae Gray, 1827 - Bulla
- Family PhilinidaePhilinidaePhilinidae is a family of medium-sized, sea slugs, marine opisthobranch gastropod mollusks. They are headshield slugs, in the Cephalaspidea.-Genera:Genera within the family Philinidae include:* Johania Monterosato, 1884* Laona A. Adams, 1865...
Gray, 1850 - PhilinePhilinePhiline is a genus of sea slugs or sea snails, marine gastropod molluscs in the family Philinidae, the headshield slugs or paper bubbles. -Species:Species within the genus Philine include:* Philine abyssicola Valdès, 2008... - Family AglajidaeAglajidaeAglajidae is a family of often colorful, medium-sized, sea slugs, marine opisthobranch gastropod mollusks. These are not nudibranchs; instead they are headshield slugs, in the clade Cephalaspidea.-Genera:...
Pilsbry, 1895–96 - Aglaja, ChelidonuraChelidonuraChelidonura is a genus of small, sometimes colorful, sea slugs. These are headshield slugs or cephalaspideans, marine opisthobranch gastropod mollusks in the family Aglajidae...
, NavanaxNavanaxNavanax is a genus of sea slugs, marine opisthobranch gastropod mollusks in the family Aglajidae.-Species:Species in the genus Navanax include:* Navanax aenigmaticus - mysterious aglaja...
, OdontoglajaOdontoglajaOdontoglaja is a genus of sea slugs, marine opisthobranch gastropod mollusks in the family Aglajidae. -Species:Species in the genus Odontoglaja include :* Odontoglaja guamensis Rudman, 1978* Odontoglaja mosaica Gosliner, 2011...
, PhilinopsisPhilinopsisPhiliopsis is a genus of often colorful, medium-sized, sea slugs, marine opisthobranch gastropod mollusks. These are not nudibranchs; instead they are headshield slugs, in the clade Cephalaspidea... - Family PhilinoglossidaePhilinoglossidaePhilinoglossidae is a family of marine snails, gastropod mollusks in the superfamily Philinoidea.- Genera :* Philinoglossa Hertling, 1932** Philinoglossa helgolandica Hertling, 1932** Philinoglossa remanei Marcus & Marcus, 1958...
Hertling, 1932 - Philinoglossa - Family GastropteridaeGastropteridaeGastropteridae is a family of sea slugs, gastropod mollusks in the superfamily Philinoidea of the clade Cephalaspidea, the headshield slugs and bubble snails....
Swainson, 1840 - Gastropteron, Sagaminopteron, Siphopteron - Family PlusculidaePlusculidaePluscula cuica is a species of marine snail, gastropod mollusk in the superfamily Philinoidea within the clade Cephalaspidea.Pluscula cuica is the only species in the genus Pluscula. Genus Pluscula is the only genus in the family Plusculidae....
Odhner, 1968 incertae sedis - Family HaminoeidaeHaminoeidaeHaminoeidae, commonly known as the haminoeid bubble snail family, is a taxonomic family of sea snails, marine opisthobranch gastropod mollusks in the superfamily Haminoeoidea....
Pilsbry, 1893 - Atys, HaminoeaHaminoeaHaminoea is a genus of medium-sized sea snails or bubble snails, marine opisthobranch gastropod molluscs in the family Haminoeidae, the haminoea bubble snails, part of the clade Cephalaspidea, the headshield slugs and bubble snails....
, Phanerophthalmus, Smaragdinella, Ventomnestia incertae sedis - Family Bullactidae Thiele, 1826 incertae sedis
2010 taxonomy
Subsequently Malaquias (2010) moved Bullacta exarataBullacta exarata
Bullacta exarata, common name the Korean mud snail, is a species of a sea snail or bubble snail, a marine gastropod mollusc in the family Haminoeidae, the bubble snails....
(formerly the only member of Bullactidae) into the family Haminoeidae
Haminoeidae
Haminoeidae, commonly known as the haminoeid bubble snail family, is a taxonomic family of sea snails, marine opisthobranch gastropod mollusks in the superfamily Haminoeoidea....
.
Jörger et al. (2010) moved Cephalaspidea sensu stricto and Runcinacea into the Euopisthobranchia
Euopisthobranchia
Euopisthobranchia is a taxonomic clade of snails and slugs in the clade Heterobranchia within the clade Euthyneura.Euopisthobranchia was established as a new taxon by Jörger et al...
and they confirmed the placement of Acteonoidea
Acteonoidea
Acteonoidea is a superfamily of sea snails, or bubble snails, marine gastropod mollusks.- Taxonomy :In the taxonomy of Bouchet & Rocroi , the superfamily Acteonoidea has been included into the informal group "Lower Heterobranchia" , also known as the Allogastropoda.Only one of analyses by Jörger...
within the Lower Heterobranchia
Lower Heterobranchia
Lower Heterobranchia, also known as the Allogastropoda, is a group of rather specialized, highly-evolved sea slugs and sea snails, within the clade Heterobranchia...
. All families of Architectibranchia were already within the Lower Heterobranchia in the taxonomy of Bouchet & Rocroi, except for the Notodiaphanidae
Notodiaphanidae
Notodiaphana fragilis is a species of marine snail, gastropod mollusk in the clade Architectibranchia.Notodiaphana fragilis is the only species in the genus Notodiaphana...
, which has been placed in the Lower Heterobranchia since 2010, in order that the Architectibranchia can be considered to be monophyletic.