The sea is full of never-ending colorful varieties of sea slugs, ranging from red, blue, yellow, etc. Today we will discuss 15 different types of sea slugs that flaunt their beautiful orange coloration and learn some interesting facts about them.
Exploring 15 Orange Sea Slug Varieties
1) Hypselodoris babai
| Scientific Name | Hypselodoris babai |
| Size | Up to 40 mm. |
| Geographic Location | First reported from Okinawa, Japan. Also can be found in Eastern Australia, Southern Queensland, and Indonesia. |
| Identification | Orange body with large white spots. The mantle edge is white. |
These slugs are majestic-looking slugs from the family Chromodorididae. The rhinophores and gills are orange along with their body. The white spots and orange coloration often act as a warning sign for predators.
These slugs feed on the Euryspongia sponges.
2) Orange-Peel Doris
| Scientific Name | Acanthodoris lutea |
| Size | Up to 30 mm. |
| Geographic Location | North American coasts such as from Oregon to Baja Califonia, and Mexico. |
| Identification | Bright orange-colored body. Yellow specks can be seen along the entire body. |
At first, these slugs look like a bright-orange ball, but their head is distinguishable by the horny protuberances or rhinophores. An interesting fact regarding these slugs is that they give off a smell of sandalwood when they are handled.
Their naming is perfectly suitable to their characteristics, as Acantho means “Spiny” and lutea means “orange or orange-yellow“. The gills are on the back and they are white.
3) Ceylonese Gymnodoris
| Scientific Name | Gymnodoris ceylonica |
| Size | Around 5 inches. |
| Geographic Location | Tropical coasts of Indo-West Pacific. |
| Identification | White translucent body with many orange spots. The gills have an orange lining and the mantle edge has a yellow color. |
These slugs are great hunters and mainly feed on different small slugs, a sea hare called Stylocheilus striatus, and sponges. Their rhinophores are orange-tipped.
The eggs are orangish-yellow and deposited as clusters. Gymnodoris ceylonica are nocturnal and generally found in grass beds or sandy regions.
4) Spanish Shawl
| Scientific Name | Flabellina Iodinea |
| Size | Generally around 2.75 inches. |
| Geographic Location | From the Galapagos islands to British Columbia, Canada. Also found in the Gulf of California. |
| Identification | It possesses a combination of colors. The body is purple with orange cerata and the rhinophores are red. |
Their exquisite orangish-red coloration resembles the coloration pattern of traditional Spanish shawls, hence the name. These slugs can hide themselves by camouflaging while they enjoy their meal.
Although they have three different colors, all of them are derived from a single pigment, astaxanthin. The color patterns are the modified states of the same pigment.
5) Pikachu Nudibranch
| Scientific Name | Thecacera pacifica |
| Size | Maximum of 2.5 cm. |
| Geographic Location | Western Pacific coasts to the Indian Ocean. Can be found in the Atlantic Ocean. |
| Identification | Translucent orange body with black-tipped rhinophores. Contrasting blue colors visible on the rhinophore sheath and gill papillae. |
Unlike Pikachu the Pokemon, these slugs can’t generate electricity. Their color pattern is what gave them the common title. The body might seem yellowish but actually, it is translucent orange.
The rhinophore sheaths are separated from the body color through a black band. The gills also have black borders.
6) Carlson’s Halgerda
| Scientific Name | Halgerda carlsoni |
| Size | Around 2 inches. |
| Geographic Location | Various parts of the Western Pacific such as New Caledonia, Tanzania, Philippines. |
| Identification | White translucent body with bright orange tubercles or spots. |
This slug species was first described from Fiji, particularly from the Suva harbor. The foot extends the mantle.
Apart from the orange spots, the retractable gills and rhinophores have black speckles. These black speckles become dense in some species.
7) Dendrodoris Guttata
| Scientific Name | Dendrodoris guttata |
| Size | Around 30 mm. |
| Geographic Location | Various parts of Indo-West Pacific. |
| Identification | Orangish-brown background with numerous black spots. |
These slugs are from the order Dendrodorididae. They are one of the most colorful sea slugs in the tropical Indo-Pacific waters.
The rhinophores have an orange base with black tips. The mantle edge is folded in shape.
8) Kaloplocamus acutus
| Scientific Name | Kaloplocamus acutus |
| Size | Around 25 mm. |
| Geographic Location | New Caledonia, Eastern Australia, Hong Kong. |
| Identification | The body is deep orange to orangish-red. Has white speckles. Numerous pointed extensions are present. |
Their body is elongated, narrow at the tail-end, and wider at the anterior side. These beautiful creatures have white stalked papillae extending from the mantle, which are further branched. The branches are bright orange or orange-red.
9) Faithful sea slug
| Scientific Name | Chromodoris fidelis |
| Size | Between 20 to 25 mm. |
| Geographic Location | Indo-West Pacific Regions and Red Sea. |
| Identification | Creamy white mantle with bright orange mantle edge. The boundary between the orange and white coloration is burgundy to white. |
Their rhinophores are grey with black on the top and very long. The gills are also of the same greyish color. In the inner edge of the orange bands, tongue-like patches can be found which are distributed along the mantle
The “faithful” terminology might be associated with the fact that these slugs roam freely without the fear of threats as they have toxic glands present in their body.
10) Orange-clubbed sea slug
| Scientific Name | Limacia clavigera |
| Size | Up to 2 cm. |
| Geographic Location | Generally observed in North African coasts, and Atlantic Coasts of Europe. |
| Identification | Translucent to white body with striking orangish-yellow tipped outgrowths visible. |
Their name “Club shaped” signifies their orange clubs or extensions present over the mantle. Apart from these, there are small raised orange spots on the body.
The three gills situated in the back are feathery-shaped and the rhinophores have orange tips with folded ridges. Their favorite food is the encrusting (large sheet-like bryozoans) such as Electra pilosa and Membranipora membranace.
11) Magnificent sea slug
| Scientific Name | Chromodoris magnifica |
| Size | Maximum up to 60 mm. |
| Geographic Location | Found in Eastern Australia, New Guinea, Philippines, and Indonesia. |
| Identification | Bluish white mantle with black markings. The mantle is outlined with vibrant orange. |
These slugs are called “Magnificent” due to their striking color patterns. The orange mantle edge is outlined with white on both sides. The rhinophores and gills are orange and retractable. The gills have an orange circular base which separates them from the mantle color.
The foot is the same as the mantle color and in addition to that, the margin is also lined with orange-white lines. They are often confused with the Chromodoris quadricolor due to their similar appearance.
12) Greilada elegans
| Scientific Name | Greilada elegans |
| Size | 48 mm on average. |
| Geographic Location | North-Eastern Atlantic to nearby coasts of the Mediterranean Sea. |
| Identification | Translucent orange-colored body with luminous blue spots. The gills are orange with white stripes. |
Along the orange-colored mantle, an iridescent line runs through from the base of the rhinophores to the posterior end behind the gills. There are around 22 to 23 finger-like projections found on the anterior side of the mantle.
The rhinophores don’t have any sheaths and usually, papillae are absent around the gills. They feed on Bryozoans, particularly the Bugula turbinata species.
13) Orange gumdrop Sea Slugs
| Scientific Name | Berthellina citrina |
| Size | Small, around 3 cm. |
| Geographic Location | Generally found in tropical and subtropical Indo-West Pacific and Northern waters of New Zealand. |
| Identification | Translucent orange (bright red in some members) with small white specks present on the mantle. |
Although these slugs are the namesake of the sweet gumdrops, they are very distasteful to their predators since the white glands present in the mantle produce unpleasant white secretion.
Just like the other members of the genus Berthellina, there is an internal shell (or remnants of it) present inside the mantle.
A single gill is present covered with papillae on the right side of the mantle. They generally feed on sponges. However, some species of corals (such as Leptastrea sp.) are also part of their diet.
14) Orange-faced Cuthona Sea Slug
| Scientific Name | Diaphoreolis lagunae |
| Size | Grows up to 14 mm. |
| Geographic Location | Northern American Coastlines, from Oregon, USA to Baja California, Mexico. |
| Identification | White body with orange-tipped cerata. |
The Rhinophores are deep orange and extended. An opaque white midline runs along the posterior foot, along with the oral tentacles. The digestive glands or cerata are black apart from the tips.
In the front section just below the rhinophores, there is a tint of orange that contrasts the white color. Thus, they are known as ‘Orange faced”.
15) Orange-Edged Sapsucking Slug
| Scientific Name | Thuridilla lineolata |
| Size | Maximum of 3 cm. |
| Geographic Location | Mainly found in the Philippines and Indonesia. |
| Identification | Bright sky blue color on the lateral folds of the mantle and the folds have orange bands with a black boundary. |
The overall body shape of these slugs is very narrow, which is why the Rhinophores look longer than the body and have a V-shape. It has Orange tips with black boundaries.
Orange and black lines run along the entire length of the mantle to the foot and transverse down on each side, encircling the body. The remainder of the mantle and base of Rhinophores are blue.
These slugs are called “Sapsuckling” because they belong to the group of “Sacoglossan” slugs who ingest the cellular contents of the algae by piercing them.
Conclusion
The colorful slugs show Aposematism, which means that they protect themselves from predation by showing their bright colors as a “Warning Sign” or “Don’t eat me”. This becomes especially beneficial for the slugs which are diurnal and move during the daytime.
It often helps them camouflage themselves with the sponges because their coloration sometimes overlaps with the type of sponge they feed. Even the eggs are similar to the color pattern of the respective slugs!
Hi everyone. I am Sagnik. Biology has always fascinated me since my school days and that interest motivated me to pursue a Bachelor’s degree in Zoology and a Master’s degree in Biotechnology. I learned a lot of new interesting facts and information regarding the biological world we are part of. After obtaining my degree, I started working as a biology teacher through which I am able to teach students the various concepts that I have learned. Apart from my love for this subject, my passion lies in music, and I teach guitar as well. Photography, Reading comics, Drawing, and video editing are some of my other hobbies. I welcome you to a journey with me, where I will share my knowledge and excitement for the living world through my writings with you all.