One of the most colorful animals on the seabed are the nudibranchs. There are many different colors and shapes, hence they receive names such as sea bunny, dancers or sea dragons. If you want to know more about these beautiful animals, keep reading this EcologรญaVerde article where you will learn from their basic characteristics to their peculiar behavior. Don’t miss out on everything nudibranchs, their species and characteristics!
What are nudibranchs and their characteristics
the nudibranchs, also called sea slugs, are marine animals and invertebrates, whose scientific name is Nudibranchia. They belong to the gastropods, a category under which they also classify snails and oysters, but they differ because nudibranchs lack a shell.
Its name means “naked gills”, because unlike other gastropods their gills are exposed on the back and are not inside the pallial cavity. Through these gills they take oxygen from the water to be able to breathe.
Some of the characteristics of nudibranchs are:
- They have very bright colors and contrasting patterns: they warn their predators that it is dangerous to eat them. Some species can be slightly transparent.
- They have very different shapes.: They can be flattened, elongated, thick, round, long, short, or even ruffled.
- On the back and near the head have a pair of sensory organs called rhinophores: with them they perceive the molecules dissolved in the water to be able to orient themselves.
- They have various sizes: there are small ones of barely 4 centimeters, even other species of up to 40 centimeters, such as the so-called Spanish dancer Hexabranchus sanguineus.
- It is estimated that there are about 3,000 species of nudibranchs: each one of very particular colors. These species can be divided into a basic classification that we present below.
Now that you know how many species of nudibranchs there are approximately, next we are going to know their classification and where they are found.
Classification of nudibranchs
Nudibranchs can be divided into two big categories:
- aeolids: on the back they have elongated structures called cerata, which act as gills since they lack them. Here gas exchange takes place, but they can also serve as an extension of the digestive system. The latter is very useful for the defense of aeolian nudibranchs, because when they eat jellyfish they transport their own stinging nematocysts from the digestive system to the tip of the cerata, to use them as their own defense. This tip of the cerata is called cnidosac. You may be interested in knowing the types of jellyfish that exist, here.
- dorids: their gills are similar to feathers and are located at the back of the anus, their digestive system is in one piece, their mantle has peculiar ornamentations in which they store the toxic substances they use as a defense.
nudibranch habitat
Where are nudibranchs found? sea slugs they live in all the oceans and seas of the world. Most are found in the Indo-Pacific tropics, specifically in the Coral Triangle, where there is the greatest marine diversity in the world.
They prefer warm waters although some species can also be found at great depths.
Nudibranch Behavior
nudibranchs they move on marine benthos with the help of his muscular foot, similar to that of snails. There are a few species that can swim.
They have very few predators, because they have defense behaviors that make them unpleasant to be ingested. They can be toxic, incredibly camouflaged in their environment, or have spicules on the skin. added to this they have aposematismability where they exhibit bright and contrasting colors to announce danger to whoever wants to harm them.
We tell you more about Aposematism: what it is and examples in the following EcologรญaVerde article that we recommend.
Feeding of nudibranchs
nudribranchs They are predatory. They can feed on sea sponges, bryozoans, jellyfish, sea anemones and sea squirts, each species specializing in one type of food. Those who consume the latter can incorporate the defensive chemicals into their own integument, releasing a toxic mucus.
If food becomes scarcenudibranchs resort to cannibalism. Some species have organs where they store poison, used mainly by nudibranch species that eat jellyfish.
To help themselves during feeding, they have a structure inside their mouths called a radula, which serves as a sandpaper that scrapes on surfaces.
reproduction of nudibranchs
nudibranchs they are hermaphrodites, having both female and male organs. To copulate they unite facing each other. They never self-fertilize to avoid reducing their gene pool, but rather cross-breed.
The result of fertilization is a gelatinous mass of several eggs, which means that they are oviparous animals. Each egg is covered by a mucus that protects them against predators.
After 15 days of oviposition, a veliger larva will be born, characterized by having a veil with which it moves within the plankton. this larva has a protective shell that he will lose as he approaches adulthood.
In the next stage, the larva metamorphoses into a juvenile nudibranch, and here it moves to the seabed. During this stage it is common for several juveniles to gather in groups.
After nudibranch development is complete, they will become sexually mature adults ready to reproduce. His life expectancy is very short. On average they live a month.
Don’t hesitate to read this EcologรญaVerde post about hermaphroditic animals: reproduction and examples.
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