10 Strangest Types of Nudibranch

What are the strangest types of Nudibranch?

They’re already classed as one of the oceans most bizarre critters, but have you ever wondered what the strangest types of nudibranch look like?

These decadent shell-less mollusks are found in textures, shapes and colours that you never knew existed. From mythical sea creatures, to solar powered sea slugs, here are ten of the strangest along with some intriguing nudibranch facts and features!

Glaucus Atlanticus Nudibranch

Nudibranch Type Glaucus Atlanticus

Daniel Coleman

Meet the Glaucus Atlanticus, one of the worlds rarest and strangest types of nudibranch! This impressive sea slug is often referred to as a ‘Blue Dragon’ due to its mythical looks. Despite its tiny size (they grow to a maximum length of only 1 inch) the Glaucus Atlanticus has to be one of the most-eye catching creatures in the ocean.

Unlike most types of nudibranch, the pelagic Blue Dragon won’t be found dwelling on the sea bed in a usual nudibranch habitat. They actually spend the majority of their time hanging out upside down on the surface of the water.

Surviving by the mercy of the waves and the current, Glaucus Atlanticus feed on jellyfish. Although their soft bodies look fun to touch, Blue Dragons are potentially dangerous.

By storing up sting cells from the jellies they ingest, the Blue Dragon uses these to protect themselves from predators!

Janolus Sp. Nudibranch

Nudibranch Type Janolus SP

Gareth Bowen

The Janolus sp. nudibranch is a genus of the Protonotidae family of sea slugs. Their distinguishing feature includes brightly coloured stubby cerata, covering their bodies.

Their main predator is a Navanax, a large species of sea slug which is technically not a type of nudibranch, despite the fact that they really do resemble one. When the Janolus is about to be attacked, they roll themselves into a ball like a hedgehog, displaying their spiky cerata by way of protection.

Janolus are found worldwide, mostly in warm, shallow waters in Europe, Africa, Australia and Japan.

Hexabranchus Sanguineus Nudibranch

Nudibranch Type Hexabranchus Sanguineus

The Hexabranchus Sanguineus is one of the worlds most admired sea slugs. Out of 3,000 species of nudibranch, this is the only one that can swim!

Drifting gracefully through the water, they twist and turn their bodies like a Flamenco Dancer flirting with her dress... Which is why they are more commonly referred to as Spanish Dancers. Performances are usually after hours, so if you wish to see them in action its better to seek them out on a night dive.

Dance-offs are a way of attracting a mate, although Hexabranchus also move along the bottom of the reef like other types of nudibranch too. Growing up to 40cm in length, the Spanish Dancer is the largest type of nudibranch.

They are mostly found in a red colour, however yellow and sometimes patterned versions have been spotted but these are rare.

Costasiella Kuroshimae Nudibranch

Nudibranch Type Hexabranchus Sanguineus

Introducing one of the worlds cutest types of nudibranch, the Leaf Sheep (or officially, a Costasiella Kuroshimae!) Does he look a little familiar to you? That’s because this adorable nudi gets his name from a cartoon sheep named Shaun!

The tiny Leaf Sheep is found in the waters surrounding Japan, Indonesia and the Philippines and can grown up to 5mm in length. One of the strangest features of this particular species, is its unique nudibranch diet!

By grazing almost exclusively on algae, they are one of the only animals in the entire world that can perform photosynthesis by using the chloroplasts of the algae. What an incredible little critter!

Thecacera Pacifica Nudibranch

Nudibranch Type Thecacera-Pacifica

The nudibranch genus Thecacera pacifica, is also compared to a certain cartoon character, but can you guess who? If you’re a fan of anime then you will fall head over heels in love with the little Thecacera - or more aptly nicknamed, Pikachu, due to his yellow and black jelly like translucence.

Nudibranch are often regarded as an underwater photographers favourite. Divers and snorkelers seek out specific nudi’s such as the Pikachu, to add to their portfolio.

This real life Pokemon can be found off the coast of Africa and around the famous muck dive sites of Tulamben in Bali.

Flabellinopsis Iodinea Nudibranch

Nudibranch Type Flabellinopsis Iodinea

The Flabellinopsis Iodinea, or Spanish Shawl is one of the most eye-catching types of nudibranch! Their brightly coloured bodies are usually purple or blue, while their backs - a shawl of cerata, are covered in fluorescent squishy orange spikes.

Much like the Spanish Dancer, this nudi’s nickname is also inspired by dancing, as they are able to ‘swim’ and sway their bodies from side to side, while showcasing their impressive mane!

The typical habitat of a Spanish Shawl is the shallow waters of the Pacific Ocean. This nudibranchs diet consists of a species of hydroid, that contains a pigment called astaxanthin which is what makes them so vibrant!

Cyerce Elegans Nudibranch

Nudibranch Type Cyerce Elegans

The Cyerce Elegans lives up to its name, as it is surely one of the most ethereal and strangest types of nudibranch! The colour variations of their bizarre bodies range from light orange to a darker shade of brown.

Internally, you will see white polka dots and opalescent hues of green and blue. Their translucent, almost pillow-like texture makes them tricky to photograph, especially as they are known to move around a lot. The Cyerce Elegans can be found mostly in the Indo-Pacific and Hawaii.

Halgerda Batangas Nudibranch

Nudibranch Type Halgerda Batangas

Gareth Bowen

Halgerda Batangas almost look good enough to eat! Their ornate markings are characterised by an eye-catching orange pattern, dotted with sweet rounded bumps, giving this unusual nudibranch its distinctive, jelly like texture.

The Halgerda is a dorid type of nudibranch, meaning they breath through gills found on their back sides. Their cute rhinophores are used to smell out food. They originate from the island of Mactan in the Philippines, however the Halgerda can now be found throughout Indonesia, Papua New Guinea and the Solomon Islands.

Okenia Hopkinsia Rosacea Nudibranch

Nudibranch Type Okenia Hopkinsia

The hot pink Okenia Hopkinsia Rosacea, is by far one of the strangest types of nudibranch you may ever lay eyes on. It is covered in eye-popping pink tentacles or papillae, which can grow up to an inch long!

Much like other types of nudibranchs, the Okenia Rosacea has both male and female reproductive organs meaning that they are able to mate with any other Okenia.

Their pink spiral eggs are quite the match to their exterior. This nudibranch species are commonly found along the coastline of California, Oregon and Mexico.

Phyllodesmium Magnum Nudibranch

Nudibranch Type Phyllodesmium Magnum

Gareth Bowen

The Phyllodesmium Magnum is a type of aeolid nudibranch that uses its cerata (the spikes on its back) as a way of breathing, digesting and defence.

However, the Magnums cerata are more than multi-functional, since they also act as solar panels! This particular nudibranchs diet consists of soft corals and cnidarian (anemones).

By feeding on algae from within the anemones and corals, these solar powered nudis store up the absorbed algae which continues to photosynthesise within its cerata, providing them with an ongoing source of food and sugars. Looks like this type of nudibranch is helping to save the reef in their own unique way too!

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