There are all kinds of amazing animals in the ocean.
Some of them are completely unknown by the average person.
The nudibranch is one such curious animal.
A nudibranch is basically a snail with no shell, sometimes called a sea slug.
The bushy tuft on the back of this nudibranch is actually the animal’s gills, which is
where nudibranchs get their name.
Nudibranch means means “naked-gill.”
There are thousands of species of nudibranchs in the world’s oceans in thousands of different
color patterns, which makes them very popular with underwater photographers.
But the bright coloration isn’t just designed to look cool.
Scientists call it aposematic—it’s designed to warn predators that it won’t make a good
meal.
Most nudibranchs produce foul tasting toxins or acids in the form of a slime on their skin.
Fish won’t eat them no matter how tempting they might look.
Unfortunately, nudibranchs are not the fastest animals on the reef, and they are somewhat
rare too.
Finding a mate under such circumstances can be challenging.
So nudibranchs are hermaphrodites, meaning each individual has both male and female organs.
When any two nudibranchs of the same species meet up, they are always compatible because
they are both male and female.
They approach each other, extend sexual organs from the side of their bodies, and exchange
both eggs and sperm with each other.
Each will then go off and lay their fertilized eggs.
This brightly colored nudibranch egg mass is produced by the equally brightly colored
Spanish Dancer nudibranch.
It is one of the largest nudibranchs on Pacific coral reefs, reaching the size of a cucumber.
The Spanish Dancer gets its name from the way it avoids predators.
When threatened, it can escape by swimming away like a flamenco dancer.
The animal has little control over the direction it swims, but it gets up into the water column
and away from the predator.
Eventually, the nudibranch stops undulating and assumes a gliding position to parachute
back down to the reef, hopefully out of harm’s reach.
The Spanish Dancer also serves as a kind of magic carpet.
It’s passenger: an Imperial shrimp.
This is transportation that offers protection from predators, as well as a steady supply
of food.
The shrimp feeds on the poop of the nudibranch!
In exchange for the free room and board, the shrimp keeps the tufted gills of the nudibranch
clean.
While the Spanish Dancer is big, some nudibranchs are bigger.
The Lemon Peel Nudibranch found in the northern Pacific reachs a foot long, making this a
small one!
And while fish won’t eat it, people do.
In the Russian Kuril Islands, it is considered a delicasy.
Nudibranchs are found in all the world’s oceans, even in the freezing water around
Antarctica!
Nudibranchs are one of the great things about life in the ocean, where even a lowly Sea
Slug can be a thing of beauty.