Nudibranchs Really Are What They Eat
Often missed due to their small size, these flamboyant snails-without-shells have adapted unique, yet beautiful defenses. Take a glimpse into the world of the nudibranch.
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Mollusks
Though they are mollusks, they lose their shell at the larval stage and proceed into adulthood naked. In fact, that's what nudibranch means: naked gills.
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Range of Sizes and Habitats
There are nearly 3000 different species, from a few millimeters to a foot long. Some live near volcanic vents, others in frigid waters, but most live on or near warm coral reefs.
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Nearly Blind
Their eyes can discern little more than lightness or darkness, but they have two rhinophores to find food through touch, scent, or taste. They're also retractable, in case a fish gets too curious.
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Hermaphrodites
Generally slow moving loners, the fact that they can mate with any of their species that happen by increases the chances of reproduction. After a successful encounter, both scoot away pregnant.
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Egg Ribbons
Eggs are laid by the thousands in colorful ribbons. After hatching, the free-swimming larvae eventually find a home on the ocean floor and quickly move into adulthood.
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Short-lived
The nudibranch life cycle is very short. Egg to natural death can be anywhere from a couple weeks to a year at most, depending on the species.
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Type 1 - Dorid
There are two types of nudibranchs. The first have feathery, frilled gills near the rear of their bodies. Some dorids use camouflage as a defense, while others use bright colors as a warning.
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Type 2 - Aeolid
The second type have appendages called cerata of varying sizes and shapes over most of their bodies. These are used for breathing, digestion, and when needed, defense.
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Colors
Their coloring is determined by what they eat, since they take on the colors of their prey. Some species even store the toxins consumed from anemone, sponges, or coral to use later as a defense.
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Solar-powered
A few species eat zooxanthellae and store them in their cerata, basically turning their bodies into greenhouses. They then survive on the energy produced through photosynthesis.
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Some Are Surface-dwelling
One genus floats upside down near the water's surface and feeds primarily on Portuguese Man o'War. They store those dangerous nematocysts and can give you a pretty nasty sting if you pick one up.
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Hard to Find
The next time you're on a reef, look a little closer. You might catch sight of some of nature's most colorful, decorative, and interesting little creatures. Just have that camera zoom ready!
