1. The Glaucus atlanticus
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The blue ocean slug (known by various names including blue lizard and blue dragon) is a specie of medium-sized (about five to eight centimeters in length) nudibranch. It has an awkward appearance and looks as if it could be a creature out of a sci-fi movie with its appendages, anatomical structure and flat blue and silver body. This nudibranch is pelagic, and is distributed throughout the world's oceans, in temperate and tropical waters. Regions include the east and south coast of South Africa, European waters and Mozambique.
This species floats upside down on the surface tension of the ocean. The blue ocean slug can feed on a variety of larger predators, such as the Portugese Man-O-War, the Blue Sea Star and the By-The-Wind-Sailor, because of its immunity to their venom. When feeding upon these cnidarians it transfers its prey's stinging cells into its own cerata (or appendages) and then utilizes them for its own defence. It is also a hermaphrodite which means that it has both male and female reproductive organs. The cerata (tenticle-like appendages) are used in respiration, defense and digestion.
More photos of the blue ocean slug:
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2. The Nembrotha kubaryana
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The Nembrotha kubaryana, also known as the variable neon slug, is a species of colorful sea slug that can reach a total length of more than 120 mm. It is a large dark-bodied nudibranch which have green stripes running down the length of the body or green raised spots. The foot and head are a vivid red-orange. Nembrotha kubaryana uses the toxins in its prey to defend itself against predators. It stores their victim's toxins in its tissues and then releases them in a slimy defensive mucus when alarmed (via).
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3. The Cyerce nigricans
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Also known as the Sacoglossan sea slug – it is one of the 'icon' species of the Great Barrier Reef – often being used in tourist posters and brochures. As with many brightly coloured sea slugs this species produces distasteful secretions that are easily cast through the cerata (appendages) when the animal is disturbed.
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4. The Chromodoris annae
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This colourful group of species is characterized by black longitudinal lines, bluish backgrounds and orange borders. They inhabit the waters of the tropical western Pacific.
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5. The Elysia crispata
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The lettuce sea slug or Elysia crispata is a herbivore (that feeds of algae) that reaches up to 5 cm in length. They are native across the Caribbean. The lettuce sea slug is not a true nudibranch, as it is often referred, but a ’sacoglossan sea slug’. Sacoglossans feed by sucking out the chlorophyll contents of algae, and then incorporate that chlorophyll into their own tissues. Thus the slugs themselves become 'solar powered' (via).
More photos of the lettuce sea slug:
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6. The Phyllidia ocellata
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Phyllidia ocellata is a species of sea slug that can measure up to 60 mm in length. This nudibranch has a yellow body with a dorsum covered in yellow or white tubercules. Its bright coloration is a perfect example of 'warning' coloration that advises wandering predators to stay away because they give off noxious chemicals if disturbed or eaten. They feed by secreting digestive enzymes into sponges afterwards they suck the partially digested tissue into their gut.
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7. The Hypselodoris apolegma
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This odd colored sea slug is found in the Western Pacific. They are a pinkinsh-purple color and they have a white border on their mantle. Their rhinophore clubs (appendages) are an orange-yellow color that is a startling juxtaposition with the rest of their bodies.
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8. The Chelidonura Varians
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The hammerhead nudibranch or Chelidonura Varians is also referred to as the ‘prince of darkness’ of the nudibranch world with its black colour and neon markings around its mantle.
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9. The Janolus barbarensis
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10. The Glossodoris atromarginata
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