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.
The body of N. inermis can be tan, black, or purple, with yellowish streaks.[1] Yellow or orange streaks and blue dots are visible on the margins.[1] It has two large parapodial folds that run the length of either side of the body, and almost touch at the midsection.[1] This species possesses a small internal shell.[1][2] Individuals are typically between 2.5 and 10 inches in length.[1]
Navanax inermis does not possess a radula or organs associated with vision.[1][3]
This species occurs in the eastern Pacific Ocean and Gulf of California. Its range is from Monterey, California to Baja California.[4]
Navanax inermis can commonly be found on rocky intertidal regions and subtidal mudflats.[1][2][3]
Navanax inermis is a voracious carnivorous predator.[2] Common prey items include other sea slugs, like bubble snails and nudibranchs, and small fish.[4][5] As N. inermis lacks visual perception, it finds prey by using its chemoreceptors to follow the slime trails of other organisms.[1][3][4]
Navanax inermis is a simultaneous hermaphrodite.[6] Copulation can occur in groups, commonly referred to as chains, of up to four individuals.[6] In the southern portion of its range, N. inermis spawns year round, producing upwards of 800,000 eggs at a time.[4] After 7 to 19 days of development, embryos are released and live as plankton.[4]
Navanax inermis slides over surfaces with the help of a mucopolysaccharide slime trail.[3]
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.[3]
Media related to Navanax inermis at Wikimedia CommonsNavanax 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.
