Navanax inermis

{{Short description|Species of gastropod}} {{Speciesbox | name = California aglaja | image = Navanax inermis 2.jpg | image_caption = From Santa Barbara, California | taxon = Navanax inermis | authority = (Cooper, 1863) | synonyms_ref = | synonyms = * ''Doridium purpureum'' (Bergh, 1894) * ''Posterobranchaea maculata'' d'Orbigny, 1835 (nomen oblitum) * ''Strategus inermis'' J.G. Cooper, 1863 (basionym) }}

'''''Navanax inermis''''', common name the '''California aglaja''', is a large species of predatory sea slug, a marine opisthobranch gastropod mollusk in the family Aglajidae. ''Navanax'' is not a nudibranch, even though it somewhat resembles one; it belongs to a more ancient lineage of opisthobranchs called the cephalaspideans or head shield slugs and snails.

==Description== The body of ''N. inermis'' can be tan, black, or purple, with yellowish streaks.<ref name=":0">{{Cite book|title=Sea of Cortez marine invertebrates : a guide for the Pacific Coast, Mexico to Ecuador|last=N.|first=Kerstitch, Alex|date=1989|publisher=Sea Challengers|isbn=978-0930118143|edition= 1st|location=Monterey, Calif.|oclc=18520858}}</ref> Yellow or orange streaks and blue dots are visible on the margins.<ref name=":0" /> It has two large parapodial folds that run the length of either side of the body, and almost touch at the midsection.<ref name=":0" /> This species possesses a small internal shell.<ref name=":0" /><ref name=":1">{{Cite book|title=Common intertidal invertebrates of the Gulf of California|last=C.|first=Brusca, Richard|date=1980|publisher=University of Arizona Press|isbn=978-0816506828|edition=Rev. and expanded, 2nd|location=Tucson|oclc=5310036|url-access=registration|url=https://archive.org/details/commonintertidal00brus}}</ref> Individuals are typically between 2.5 and 10 inches in length.<ref name=":0" />

''Navanax inermis'' does not possess a radula or organs associated with vision.<ref name=":0" /><ref name=":4">{{Cite journal|last1=Sleeper|first1=Howard L.|last2=Paul|first2=Valerie J.|author2-link=Valerie Paul|last3=Fenical|first3=William|date=January 1980|title=Alarm pheromones from the marine opisthobranch Navanax inermis|journal=Journal of Chemical Ecology|language=en|volume=6|issue=1|pages=57–70|doi=10.1007/bf00987527|bibcode=1980JCEco...6...57S |issn=0098-0331}}</ref>

==Distribution and habitat== This species occurs in the eastern Pacific Ocean and Gulf of California. Its range is from Monterey, California to Baja California.<ref name=":5">{{Cite journal|last=Paine|first=Robert T.|date=1965|title=Natural History, Limiting Factors and Energetics of the Opisthobranch Navanax Inermis|journal=Ecology|volume=46|issue=5|pages=603–619|doi=10.2307/1935000|jstor=1935000|bibcode=1965Ecol...46..603P }}</ref>

''Navanax inermis'' can commonly be found on rocky intertidal regions and subtidal mudflats.<ref name=":0" /><ref name=":1" /><ref name=":4" />

==Ecology==

===Diet=== ''Navanax inermis'' is a voracious carnivorous predator.<ref name=":1" /> Common prey items include other sea slugs, like bubble snails and nudibranchs, and small fish.<ref name=":5" /><ref name=":2">{{Cite web|url=http://www.seaslugforum.net/find/navainer|title=The Sea Slug Forum - Navanax inermis|last=|first=|date=2010-07-15|website=www.seaslugforum.net|language=en|archive-url=|archive-date=|access-date=2018-08-12}}</ref> As ''N. inermis'' lacks visual perception, it finds prey by using its chemoreceptors to follow the slime trails of other organisms.<ref name=":0" /><ref name=":4" /><ref name=":5" />

===Reproduction=== ''Navanax inermis'' is a simultaneous hermaphrodite.<ref name=":3">{{Cite journal|last1=Leonard|first1=Janet L.|last2=Lukowiak|first2=Ken|date=1985|title=Courtship, copulation, and sperm trading in the sea slug, Navanax inermis (Opisthobranchia: Cephalaspidea)|journal=Canadian Journal of Zoology|volume=63|issue=12|pages=2719–2729|doi=10.1139/z85-406|issn=0008-4301}}</ref> Copulation can occur in groups, commonly referred to as chains, of up to four individuals.<ref name=":3" /> In the southern portion of its range, ''N. inermis'' spawns year round, producing upwards of 800,000 eggs at a time.<ref name=":5" /> After 7 to 19 days of development, embryos are released and live as plankton.<ref name=":5" /> thumb|''N. inermis'' with a yellow base color

===Locomotion=== ''Navanax inermis'' slides over surfaces with the help of a mucopolysaccharide slime trail.<ref name=":4" />

===Defense=== When disturbed, ''N. inermis'' secretes a bright yellow substance into its slime trail, which can persist for several hours. This secretion causes some other organisms to break pursuit of the slug.<ref name=":4" />

==References== {{Reflist}}

*{{Commons category-inline|Navanax inermis}}

Category:Aglajidae Category:Western North American coastal fauna Category:Marine fauna of the Gulf of California Category:Molluscs of the Pacific Ocean Category:Gastropods described in 1863 Category:Taxa named by James Graham Cooper