California Aglaja
ExploreInvertebrate
California Aglaja
navanax inermis
The California Aglaja (Navanax inermis), commonly known as the Navanax, is a striking predatory sea slug native to the eastern Pacific coast. Although it looks similar to a nudibranch, it belongs to the Cephalaspidea order, or headshield slugs. This voracious carnivore is a master hunter of the intertidal zone, navigating muddy estuaries, sandy bays, and rocky tide pools. Unlike passive grazers, the Navanax actively tracks down prey by detecting chemical signals in their slime trails. It is famous among marine biologists for its colorful, velvet-like body and its dramatic, vacuum-like feeding method, where it rapidly engulfs its target whole.
Habitat: Typically found in muddy estuaries, sandy bays, eelgrass beds, and rocky intertidal tide pools along the Pacific coast.
Appearance
The California Aglaja features an elongated, cylindrical body that can grow up to 22 centimeters in length. Its base color ranges from deep dark brown to velvety black, beautifully ornamented with bright yellow or orange longitudinal stripes and brilliant metallic blue spots along its parapodia. It lacks an external shell, instead possessing an internal, reduced shell plate hidden within its mantle. The head is flattened into a characteristic shield shape used for burrowing, and it lacks the highly visible nudibranch rhinophores, relying instead on sensitive chemical-receptive bristles near its mouth.
KingdomAnimaliaPhylumMolluscaClassGastropodaOrderCephalaspideaFamilyAglajidaeGenusNavanax
Category
InvertebrateRarity
Common
Danger
1/5 · Very low
Snaps
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Interesting facts
Despite having eyes, the California Aglaja is essentially blind and relies almost entirely on its highly developed sense of touch and chemoreception to navigate and hunt.
It is a simultaneous hermaphrodite, meaning a single individual possesses both male and female reproductive organs and can occasionally form mating chains with multiple individuals.
Its feeding mechanism is so fast and powerful that it acts like a biological vacuum cleaner, sucking in prey before they can react.
When digesting bubble snails, it dissolves the soft body of the snail inside its gut and later regurgitates the completely intact, empty shell.
Special abilities
Ability
Slime Trail Tracking
Detects and follows the mucus trails of other gastropods using specialized chemical receptors on its front sensory bristles.
Ability
Pharyngeal Vacuum
Employs a highly muscular, toothless pharynx to generate a powerful suction that rapidly sucks prey whole into its mouth.
Ability
Chemical Warning Ink
Expels a thick, yellow-to-red toxic ink from its mantle cavity when threatened to deter predators like crabs and fish.
Measurements & details
- Length
- 5-22 cm
- Weight
- 0.05-0.35 kg
- Lifespan
- 1-2 years
- Clutch Size
- 10000-80000
- Incubation
- 10-20 days
Diet & Feeding
A voracious predator that feeds primarily on other sea slugs, bubble snails, and nudibranchs, often swallowing them entirely whole.
Age differences: Juveniles feed on tiny gastropods and small bubble snails, transitioning to larger sea slugs and cannibalism as they mature.
Primary Foods
- California Bubble Snail
- Opalescent Nudibranch
- Other Navanax individuals
- Yellow-edged Cadlina
Foraging Method
- Pursuit
Ecological connections
hunts
California Bubble Snail
Bulla gouldiana
The California Aglaja actively hunts and consumes this common bubble snail, swallowing it whole.
hunts
California Aglaja
Navanax inermis
Larger individuals regularly hunt and cannibalize smaller members of their own species.
hunts
Opalescent Nudibranch
Hermissenda crassicornis
Navanax will track and prey upon this colorful nudibranch despite its stinging nematocysts.
Traits
No trait badges are assigned for this object yet.
Also known as
No aliases listed yet.
Collections
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Safety
Danger
1/5 · Very low
No special safety notes yet.
Frequently Asked Questions
How to identify California Aglaja?
The easiest way to identify California Aglaja is to use the Snappit nature identifier app.
How long is California Aglaja?
5-22 cm
How much does California Aglaja weigh?
0.05-0.35 kg
How long does California Aglaja live?
1-2 years
What does California Aglaja eat?
A voracious predator that feeds primarily on other sea slugs, bubble snails, and nudibranchs, often swallowing them entirely whole.
Where is California Aglaja usually found?
Typically found in muddy estuaries, sandy bays, eelgrass beds, and rocky intertidal tide pools along the Pacific coast.
How does California Aglaja hunt?
Pursuit
How many eggs does California Aglaja lay?
10000-80000
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