Help the development of the site, sharing the article with friends!
Have you ever wondered what animals that lack a brain are like, how do they perform their vital functions without a brain that allows them to recognize signals from the outside and give them a stimulus to move or feed? Once again, nature surprises us with different adaptations and the development of new tools and abilities within the animal world for those species that do not have a brain. It is interesting to discover how the majority of brainless animals are found in marine ecosystems around the world, generally having simpler and more primitive life forms than other animal species that, on the contrary, inhabit ecosystems. terrestrial.
Let's get to know more closely in this article from Green Ecologist to 14 animals without brains: list and photos.
Portuguese caravel
Known as one of the colonial organisms more surprising the animal kingdom, the Portuguese caravelPhysalia physalis) it is characterized by lacking a brain. Although by its appearance we could say that it is a jellyfish, the reality is that this animal is made up of four different species of hydroids (hydrozoans belonging to the group of Cnidarians), which perform well differentiated functions within the correct functioning of the colonial organism.
In addition to the lack of brain, the Portuguese man-of-war stands out for the powerful venom present in its stinging cells, which it uses to immobilize its prey.
Inverted jellyfish
If you were wondering if jellyfish have a brain or notThe answer is that they do not have a nervous system. Entering the world of jellyfish (Class Scifozoans), the inverted jellyfishCassiopea xamachana) It stands out as one of the most striking and particular species, due to its strange appearance and greenish color.
In the case of this species of jellyfish, its anatomy includes 8 long tentacles and a bell-shaped body and that lacks brain. On many occasions it is common to find inverted jellyfish that move on the shell of crabs, thus facilitating them to travel greater distances and, in turn, the jellyfish protect the crabs with the stinging cells of their tentacles, against possible predators.
Ctenophores, brainless animals that are part of plankton
The ctenophoresCtenophora) They are one of the animals that don't have brains smallest and most curious that there are in the seas. It is one of the animals that are part of the well-known zooplankton, which is the basis of the diet of other well-known animals: baleen whales or mysticetes. Another curious fact about them is that they do have a very simple nervous system.
In this other article you can discover what plankton is and its importance and see that there are different types, such as zooplankton (made up of animals) and phytoplankton (made up of plants), among others.
Sea squirts
Another one of the strangers animals that don't have brains Are the Sea squirts (Ascidiacea) of the Subfilo Urochordata. These are marine animals found in all the seas of the world and that live on rocks and other surfaces, they feed on small particles that they trap through their absorption and filtering system. They do not have a brain, but neither do they have a nervous system or a heart.
Sea stars
One of the most emblematic animals of the entire marine ecosystem are, without a doubt, the precious starfish (Class Asteroidea, Phylum Echinoderms). Known for their surprising ability to regenerate the appendages of their body, starfish also stand out for being brainless animals.
Its anatomy is quite simple and it has other peculiarities, such as the ability to move thanks to the entry of water into its aquifer vascular system.
Sea urchins
Following within the group of echinoderms, the sea urchins (Class Echinoidea) are also characterized by lack of a brain and nervous system in their anatomy.
The radial symmetry that characterizes all species of this class of echinoderms, guarantees a fairly rudimentary but effective anatomy, allowing sea urchins to develop their main vital functions even though they lack organs that at first glance seem essential for their survival, such as the brain or the heart.
Holothurians or sea cucumbers
Commonly known as sea cucumbers, holothurians (Class Holothuroidea) They are another of the classes of echinoderms that abound in the marine ecosystems of almost the entire planet. They are characterized by their long and vermiform appearance, as well as their soft and muscular texture. They are quite simple organisms, lacking a brain and with the naked eye we can observe in their anatomy an oral opening in the anterior part and another posterior opening with anal function.
These are some of the rare marine animals that are in danger of extinction, here you can see more information about them and others in the same situation.
Sea lilies
Continuing with this list of brainless animals, we stop to meet this strange animal. Perhaps somewhat less well known than the stars, urchins and sea cucumbers, the sea lilies or feathered stars (Class Crinoids) They are also included within the large and diverse group of echinoderms.
It is considered the oldest class of echinoderms and, in turn, the least abundant today. Only 600 species survive in almost all the seas of the world. Their anatomy gives them a branched appearance with numerous arms, lacking a well-defined body.
Sea sponges
Another of the most emblematic animals of the marine ecosystems and ocean floors are the curious sea sponges, belonging to Poriferous group.
They are characterized by their ability to filter water and nutrients to survive, as well as having one of the simplest anatomies within the Animal kingdom. They lack both authentic tissues and limbs, as well as certain organs, including the brain.
If you want to know more about these curious brainless animals, we recommend reading this article about the sea sponge: what it is and its characteristics.
Sea anemones
Although on many occasions, due to their appearance and way of life, it is difficult to distinguish and recognize these organisms as animals, the sea anemones (Order Actiniaria) they fill the ocean floor with life, adhering to rocks and other substrates.
There are more than 1,200 species of sea anemones, all of them stand out for not having a brain, for their colors and tentacles of greater or lesser length, as well as their inability to move. Another aspect that allows us to recognize these animals quickly is the symbiosis they have with clown fish, since they live between the tentacles of anemones.
Marine corals, one of the most curious brainless animals
Among the most mysterious and surprising organisms that nature hides in marine ecosystems of the planet stand out marine corals (Phylum Cnidarians).
Is about colonial organisms without brains that, grouped forming the majestic coral reefs, fill with color and serve as shelter for numerous marine species, both small and large.
Lancet fish
Known as one of the organizations of greatest interest in the transition between invertebrate and vertebrate animals, the lancet fishBranchiostoma lanceolatum) inhabits the shallow waters of the Mediterranean and the Atlantic.
Its anatomy is a mystery: it lacks a skull and a well-differentiated brain, as well as a skeleton and jaws. However, it has a very simple nervous system, consisting of a dorsal cord protected under some vertebrae.
Image: AsturNatura
Leeches
This group of invertebrates belonging to the Phylum Annelida, Subclass Hirudinea, we can find them both in marine, terrestrial and freshwater habitats, in which they are especially predominant.
Commonly known for their ability to suck blood from their prey, leeches They also stand out for some curiosities of their anatomy, such as the absence of a well-differentiated brain centralized within the nervous system of the animal.
Earthworm
Like leeches, Earthworms they belong to Phylum Annelida, but they are included within the class Crassiclitellata, since they differ in various anatomical and lifestyle characteristics.
Earthworms are directly descended from marine ancestors, aquatic worms, so they currently have many characteristics of their ancestors, including the absence of a brain in their anatomy.
Both earthworms and leeches, mentioned above, are annelids that breathe through the skin. If you want to know better about these annelids and other Animals that breathe through the skin, don't miss this other post.
If you want to read more articles similar to 14 animals without brains: list and photos, we recommend that you enter our category of Animal Curiosities.
Bibliography- Diéguez, A. et al., (2014) Animal and human nature. Editorial Siglo XXI: New Library (Collection reason and society).
- Conway S. & Collins, D. (1996). "Middle Cambrian Ctenophores from the Stephen Formation, British Columbia, Canada". Philosophical Transactions of the Royal Society: Biological Sciences (London: The Royal Society), Volume 351 (1337), pages: 279-308.
- Pandolfi, M. (January 15, 2013) Learning from fish: a brain with unique properties and a strategic resource. Conicet.
