Sea slugs, are basically sea snails without a shell.
But losing the shell doesn't necessarily mean that they are completely defenseless.
Some can blend in with their surroundings, while others can get a bit more dangerous
and use their stinging cells for protection.
Often the term “nudibranch” is used for all sea slugs.
However, while all nudibranchs are sea slugs, not all sea slugs are nudibranchs.
With around 3,000 different species of sea slugs living inside and outside all forms
of water bodies that present on the planet, stay with us as we're looking at 10 of the
most beautiful sea slugs in the world.
Number 10.
Native to the west coast of North America and farther south, the Flabellinopsis iodinea
or Spanish shawl is a very colorful sea slug with purple body, orange cerata and scarlet
rhinophores.
The neon orange appendages on the back of this species are the cerata which extract
oxygen from the sea water they are surrounded by and live in.
The cerata are also extensions of the digestive system, and are used to store the stinging
cells of the anemones and fan-like hydroids they eat.
Meanwhile, the red rhinophores are sensory structures used for detecting the presence
of possible mates and prey.
Number 9.
Found in the tropical waters of the central Indo-Pacific region and is known to range
from Malaysia to Fiji and the northern coast of Australia,
the Chromodoris lochi is one of a group of translucent white or bluish-white chromdorids
with dark blue or black longitudinal lines.
Growing up to 4cm in length, no individual is the same within this species, and the retractable
gills and contractable rhinophores range in colour from a translucent straw-color through
to pink and light orange.
Number 8.
Occuring in the tropical Western Indo-Pacific, the Nembrotha kubaryana is a very colorful
species with green stripes or raised spots running down the large dark body,
while the margin of the foot and head is a vivid red-orange.
As this species feed on colonial sea squirts, also known as ascidians, they are able to
exude noxious antifeedant chemicals as a mucus when they are threatened.
Number 7.
Occuring in the Eastern Pacific Ocean, the Dirona albolineata is not as colorful as the
other sea slugs on this list, but it is still as beautiful with its large flat translucent
cerata.
As it specializes on either bryozoans or small snails instead of anemones, this species does
not incorporate the stinging cells into their cerata for protection.
Instead, when being attacked or in danger, they will shed their cerata and flee from
the predators.
Number 6.
Commonly found in the Red Sea, the Chromodoris quadricolor is named so because of its yellow,
white, blue and black coloration.
The background colour of the body is bluish white which varies in intensity from one specimen
to another.
On the mantle, the bluish area is outlined by two continuous black lines and a median
continuous line.
All around there is a white band, followed by another wider of orange color and a white
edge.
Number 5.
Occuring in the Pacific and the Indian Ocean, the Cyerce nigricans is actually one of the
icon species of the Great Barrier Reef, where it is often being used in tourist posters
and brochures.
Although most species within this and the related genus, Polybranchia, are cryptically
coloured, Cyerce nigricans breaks the rule with its beautiful black, white and orange
coloration.
As with many brightly coloured sea slugs, this species produces distasteful secretions,
and the cerata are easily casted when the animal is disturbed.
Distasteful secretions and autotomy are two common defensive strategies sea slugs use
against predatory fish.
Number 4.
Living in the Arctic Ocean and cold regions of the North Atlantic Ocean, the Clione limacina
is just beautiful to watch.
Their wing-like fins propel them in a manner reminiscent of flying, which is partially
why they are commonly known as sea angels.
They are also fairly translucent, creating an almost ethereal illusion as it allows for
view of their internal organs like their gonads, which are a pretty pink and orange hue.
Number 3.
Found in the Pacific Ocean, the Hypselodoris apolegma is truly an eye catcher with its
amazing coloration.
Its rich pinkish purple body contrasts beautifully with the white mantle edge and orange yellow
gills and rhinophore clubs.
Due to its very specific diet, the etherial sponge, this colorful sea slug only thrives
in the western tropical reagion of the Pacific Ocean where the sponges grow.
Number 2.
Living from Kodiak Island Alaska to Northern California, the Hermissenda crassicornis is
absolutely one of the most beautiful of all the invertebrates.
The colour of this species varies from one locality to another, but it is always easily
recognizable by the orange stripe along its head area and the white stripes on the cerata.
The life of this slug can be violent.
Individuals who run into each other will fight, especially if the run-in included head-on
contact, where the winner tends to eat the loser.
Number 1.
Occuring throughout the world's oceans in temperate and tropical waters, the Glaucus
atlanticus totally deserves to be on this list with its appearance that looks like out
of this world.
Also known as blue sea dragon, this species makes use of countershading with the blue
side of their body faces upwards, blending in with the blue of the water,
while the silver grey side faces downwards, blending in with the sunlight reflecting on
the ocean's surface when viewed facing upwards underwater.
As it feeds on venomous siphonophores, this slug stores stinging nematocysts from the
siphonophores within its own tissues as defence against predators.
This is the reason why humans handling it may receive a very painful and potentially
dangerous sting.