Opalescent Nudibranch
ExploreInvertebrate
Opalescent Nudibranch
hermissenda opalescens
The Opalescent Nudibranch (Hermissenda opalescens) is one of the most breathtaking and aggressively competitive sea slugs found along the Pacific coast of North America. Renowned for its brilliant, glowing coloration, this tiny marine gastropod looks like an underwater firework. Despite its delicate, ethereal appearance, it is a highly active and territorial carnivore, often engaging in fierce battles with other nudibranchs. Its body is covered in soft, finger-like projections called cerata, which not only assist in breathing but also serve as a sophisticated defense system. Tidepoolers and divers alike are continually captivated by its striking presence, making it a favorite find among coastal explorers. Its ability to navigate complex rocky intertidal zones while carrying a stolen arsenal of stinging cells makes it a fascinating marvel of evolutionary adaptation.
Habitat: Typically found in rocky intertidal zones, tidepools, kelp forests, and on boat docks and pilings along the Pacific coast.
Appearance
This species features a translucent, pearly-white to bluish-grey body highlighted by a brilliant neon orange stripe running down the center of its back, flanked by bright blue or gold lines. Its back is crowded with numerous long, pointed cerata that display vibrant bands of orange, white, and iridescent blue. Two prominent, yellowish-white tentacles extend from its head alongside a pair of ringed rhinophores, which act as sensory organs. It typically reaches lengths of 2 to 8 centimeters, moving with a graceful yet surprisingly rapid crawling motion.
KingdomAnimaliaPhylumMolluscaClassGastropodaOrderNudibranchiaFamilyMyrrhinidaeGenusHermissenda
Category
InvertebrateRarity
Common
Danger
1/5 · Very low
Snaps
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Interesting facts
If they lose their cerata during a fight or predator attack, they can shed them and completely regenerate them within a few weeks.
The brilliant orange and blue lines on its body act as warning coloration, signaling to potential predators that they are highly toxic and armed with stolen stinging cells.
They lay their eggs in highly distinct, white or pinkish-white spiral gelatinous ribbons that look like tiny lace doilies draped over seaweed.
Special abilities
Ability
Kleptocnidism
The nudibranch consumes stinging anemones and redirects their unexploded stinging cells to the tips of its own cerata for self-defense.
Ability
Aggressive Territoriality
Unlike many passive slugs, this species actively fights rivals, using its radula to bite and even consume competitors.
Ability
Chemosensory Navigation
Uses highly sensitive, ribbed rhinophores on its head to detect chemical cues in the water, helping it locate prey, mates, or rival nudibranchs.
Measurements & details
- Length
- 2-8 cm
- Weight
- 0.002-0.015 kg
- Lifespan
- 1 years
- Clutch Size
- 1000-10000
- Incubation
- 5-10 days
Diet & Feeding
An aggressive predator that feeds on a wide variety of sessile marine invertebrates, including hydroids, anemones, bryozoans, and other nudibranchs.
Age differences: Juveniles feed primarily on small hydroids, while adults expand their diet to include larger anemones and conspecifics.
Primary Foods
- Hydroids
- Aggregating Anemones
- Ascidians
- Bryozoans
- Other Nudibranchs
Foraging Method
- Foraging
Ecological connections
hunts
Double-toothed Hydroid
Obelia geniculata
Feeds heavily on colonies of this hydroid, absorbing its nematocysts for defense.
eaten by
Sunflower Sea Star
Pycnopodia helianthoides
Preyed upon by large sea stars that patrol tidepools and rocky reefs.
hunts
Aggregating Anemone
Anthopleura elegantissima
Feeds on the tentacles of this anemone, acquiring defensive stinging cells.
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 Opalescent Nudibranch?
The easiest way to identify Opalescent Nudibranch is to use the Snappit nature identifier app.
How long is Opalescent Nudibranch?
2-8 cm
How much does Opalescent Nudibranch weigh?
0.002-0.015 kg
How long does Opalescent Nudibranch live?
1 years
What does Opalescent Nudibranch eat?
An aggressive predator that feeds on a wide variety of sessile marine invertebrates, including hydroids, anemones, bryozoans, and other nudibranchs.
Where is Opalescent Nudibranch usually found?
Typically found in rocky intertidal zones, tidepools, kelp forests, and on boat docks and pilings along the Pacific coast.
How does Opalescent Nudibranch hunt?
Foraging
How many eggs does Opalescent Nudibranch lay?
1000-10000
Snap Map
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Recent Snaps
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Where to spot
Park20 sightings12 species
California, US
Audubon Canyon
You might spot Hilton's Aeolid and Opalescent Nudibranch.
View guide →
Zoo30 sightings12 species
California, US
Birch Aquarium
You might spot Sea Lion, Western Gull, and Brandt's Cormorant.
View guide →
Aquarium30 sightings12 species
California, US
Birch Aquarium
You might spot Sea Lion, Western Gull, and Brandt's Cormorant.
View guide →
Park21 sightings12 species
US
Bodega Bay
You might spot Ochre Sea Star and Giant Green Anemone.
View guide →
Park30 sightings12 species
California, US
Crystal Cove Historic District
You might spot Sunburst Anemone, Ochre Sea Star, and Striped Shore Crab.
View guide →
Park12 sightings12 species
California, US
Sherman Library and Gardens
You might spot Sunburst Anemone and Striped Shore Crab.
View guide →
