''Janolus'' is a
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...
of small to large
sea slug
Sea slug is a common name for some marine invertebrates with varying levels of resemblance to terrestrial slugs. Most creatures known as sea slugs are gastropods, i.e. they are sea snails (marine gastropod mollusks) that over evolutionary ...
s, or more accurately
nudibranch
Nudibranchs () are a group of soft-bodied marine gastropod molluscs which shed their shells after their larval stage. They are noted for their often extraordinary colours and striking forms, and they have been given colourful nicknames to mat ...
s,
marine
Marine is an adjective meaning of or pertaining to the sea or ocean.
Marine or marines may refer to:
Ocean
* Maritime (disambiguation)
* Marine art
* Marine biology
* Marine debris
* Marine habitats
* Marine life
* Marine pollution
Military
* ...
gastropod 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 es ...
s, in the
family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
Janolidae.
The name ''Janolus'' is derived from the two-headed god
Janus
In ancient Roman religion and myth, Janus ( ; la, Ianvs ) is the god of beginnings, gates, transitions, time, duality, doorways, passages, frames, and endings. He is usually depicted as having two faces. The month of January is named for Janu ...
, in ancient Roman mythology.
Description
Adult individuals of ''Janolus'' species can be between 2.5 cm to 8 cm long, depending on the species. They are semi-translucent and the body is covered in short
cerata
:''The tortrix moth genus ''Cerata'' is considered a junior synonym of ''Cydia.
Cerata, singular ceras, are anatomical structures found externally in nudibranch sea slugs, especially in aeolid nudibranchs, marine opisthobranch gastropod mollus ...
.
Distribution
''Janolus'' species are found in many areas world-wide, including
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located enti ...
,
Australia,
Japan and
Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
.
Ecology
Habitat
This genus of nudibranch is found in shallow and
subtidal
The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth.
From the point of view of marine biology it forms a relatively stable and well-illuminated ...
waters.
Feeding habits
''Janolus'' species feed on
Bryozoa
Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about long, they have a special feeding structure called a ...
, moss animals.
Predators
In California, ''
Navanax'' is a known predator of ''Janolus''. ''Navanax'' tracks the slime of ''Janolus'' by using
chemoreceptors
A chemoreceptor, also known as chemosensor, is a specialized sensory receptor which transduces a chemical substance (endogenous or induced) to generate a biological signal. This signal may be in the form of an action potential, if the chemorecep ...
. When ''Janolus'' is about to be caught, it rolls into a ball, leaving its cerata exposed.
Species
Species in the genus ''Janolus'' include:
[MolluscaBase (2019). MolluscaBase]
''Janolus'' Bergh, 1884.
Accessed on 2020-10-20.
* ''
Janolus anulatus''
Camacho-Garcia & Gosliner, 2006
* ''
Janolus australis
''Janolus'' is a genus of small to large sea slugs, or more accurately nudibranchs, marine gastropod mollusks, in the family Janolidae. The name ''Janolus'' is derived from the two-headed god Janus, in ancient Roman mythology.
Description
Adul ...
''
Bergh, 1884
* ''
Janolus chilensis''
M.A. Fischer, Cervera & Ortea, 1997
* ''
Janolus comis''
Er. Marcus, 1955
* ''
Janolus eximius''
Miller & Willan, 1986
* ''
Janolus faustoi''
Ortea & Llera, 1988
* ''
Janolus flavoanulatus
''Janolus flavoanulatus'' is a sea slug species. The specific name is derived from Latin words flavus (“yellow”) and anulatus (“ringed”). These soft-bodied mollusks are known for their extraordinary colors and prominent forms. The first d ...
''
Pola & Gosliner, 2019
* ''
Janolus hyalinus
''Janolus'' is a genus of small to large sea slugs, or more accurately nudibranchs, marine gastropod mollusks, in the family Janolidae. The name ''Janolus'' is derived from the two-headed god Janus, in ancient Roman mythology.
Description
Adul ...
''
(Alder and Hancock, 1854)
* ''
Janolus ignis
''Janolus'' is a genus of small to large sea slugs, or more accurately nudibranchs, marine gastropod mollusks, in the family Janolidae. The name ''Janolus'' is derived from the two-headed god Janus, in ancient Roman mythology.
Description
Adul ...
''
Miller & Willan, 1986
* ''
Janolus incrustans
''Janolus'' is a genus of small to large sea slugs, or more accurately nudibranchs, marine gastropod mollusks, in the family Janolidae. The name ''Janolus'' is derived from the two-headed god Janus, in ancient Roman mythology.
Description
Adul ...
''
Pola & Gosliner, 2019
* ''
Janolus kinoi
''Janolus'' is a genus of small to large sea slugs, or more accurately nudibranchs, marine gastropod mollusks, in the family Janolidae. The name ''Janolus'' is derived from the two-headed god Janus, in ancient Roman mythology.
Description
Adul ...
''
Edmunds & Carmona, 2017
* ''
Janolus mirabilis
''Janolus'' is a genus of small to large sea slugs, or more accurately nudibranchs, marine gastropod mollusks, in the family Janolidae. The name ''Janolus'' is derived from the two-headed god Janus, in ancient Roman mythology.
Description
Adul ...
''
Baba & Abe, 1970
* ''
Janolus mokohinau
''Janolus'' is a genus of small to large sea slugs, or more accurately nudibranchs, marine gastropod mollusks, in the family Janolidae. The name ''Janolus'' is derived from the two-headed god Janus, in ancient Roman mythology.
Description
Adul ...
''
Miller & Willan, 1986
* ''
Janolus mucloc
''Janolus'' is a genus of small to large sea slugs, or more accurately nudibranchs, marine gastropod mollusks, in the family Janolidae. The name ''Janolus'' is derived from the two-headed god Janus, in ancient Roman mythology.
Description
Adult ...
''
(Er. Marcus, 1958)
* ''
Janolus rebeccae
''Janolus'' is a genus of small to large sea slugs, or more accurately nudibranchs, marine gastropod mollusks, in the family Janolidae. The name ''Janolus'' is derived from the two-headed god Janus, in ancient Roman mythology.
Description
A ...
''
Schrödl, 1996
* ''
Janolus savinkini
''Janolus savinkini'', common name purple-tipped janolus, is a colorful sea slug, an arminina (a suborder of ''Janolus'') nudibranch, a marine gastropod mollusc in the family Janolidae. The body and caruncle of this species are yellow with a hu ...
''
Martynov & Korshunova, 2012
* ''
Janolus toyamensis
''Janolus toyamensis'', common name purple-tipped janolus, is a colorful sea slug, an arminina (a suborder of ''Janolus'') nudibranch, a marine gastropod mollusc
Mollusca is the second-largest phylum of invertebrate animals after the Arth ...
''
Baba & Abe, 1970
* ''
Janolus tricellariodes''
Pola & Gosliner, 2019
;Species brought into synonymy:
* ''Janolus barbarensis''
(J. G. Cooper, 1863):synonym of ''
Antiopella barbarensis''
(J. G. Cooper, 1863)
* ''Janolus capensis''
Bergh, 1907:synonym of ''
Antiopella capensis''
(Bergh, 1907) (original combination)
* ''Janolus costacubensis''
Ortea & Espinosa, 2000:synonym of ''Janolus comis''
Er. Marcus, 1955
* ''Janolus cristatus''
(Delle Chiaje, 1841):synonym of ''
Antiopella cristata''
(Delle Chiaje, 1841)
* ''Janolus flagellatus''
Eliot, 1906:synonym of Janolus hyalinus
(Alder & Hancock, 1854) (dubious synonym)
* ''Janolus fuscus''
O'Donoghue, 1924:synonym of ''
Antiopella fusca''
(O'Donoghue, 1924) (original combination)
* ''Janolus longidentatus''
Gosliner, 1981:synonym of ''
Antiopella longidentata''
(Gosliner, 1981) (original combination)
* ''Janolus nakaza''
(Gosliner, 1981):synonym of ''
Bonisa nakaza''
Gosliner, 1981
* ''Janolus novozealandicus''
(Eliot, 1907):synonym of ''
Antiopella novozealandica''
Eliot, 1907
* ''Janolus praeclarus''
(Bouchet, 1975):synonym of ''
Antiopella praeclara''
Bouchet, 1975
References
{{Taxonbar, from=Q3020001
Proctonotidae