If I ask you about an animal, probably the first ones that will come to mind will be mammals, such as the tiger, the lion, a bear, a cat or a dog; If I ask you about a reptile, in your mind the image of a crocodile or a snake will come, and so we can continue, but what if I ask you about animals without a brain?
If you are knowledgeable about the fauna in general then you will have said the jellyfish, and you are correct, but what if I ask you for another?
I hope you have not thought of the octopus just because it is on the cover, it is just an image to not “spoiler” the content.
That is why this time we will mention 5 animals without brains:
The most famous, creepy and prehistoric is the jellyfish.
Instead of a brain, these incredible animals have what is known as a neural network, which is a system of nerve cells intertwined throughout the animal's body, which allows them to "feel" the presence of food, predators or potential companions.
Despite not having a brain, the jellyfish that swims upside down "Cassiopeia" has telltale signs of sleep, according to scientists in an article published Thursday in the journal Current Biology.
The researchers finally determined that it met three important sleep criteria: periods of decreased activity known as behavioral inactivity, reduced response to stimuli and increased sleep after not sleeping.
The image shows two Cassiopeia jellyfish.
2.- Sea urchins
Echinoids (Echinoidea) live on all seabed, up to 2500 meters deep. The digestive system is composed of a large stomach and a mouth located on the oral face (lower part) of the hedgehog.
The life of these animals is to crawl on the ocean floor in search of food, but since they don't have a brain, there is no planning for it.
There are about 900 types of species.
3.- Sea sponges
SpongeBob didn't have a brain? Well, if SpongeBob Square Pants existed just like our sea sponges, then no, it wouldn't have a brain.
In addition to not having a brain, sea sponges also have no digestive, nervous or circulatory systems.
They have a lot of non-specialized cells that can migrate through your body and become any type of specific cell that is needed.
Something curious is that without having internal organs they are able to sneeze.
When something "irritates" them, a sponge absorbs a large amount of water and then contracts their body and sprays who bothers them with a sneeze-jet that can last up to 60 minutes.
Now you know where the powers of some Pokémon come from.
Patrick Star didn't have a brain either? If we follow the same previous theme, then no (although in the series it seemed not to have either).
Asteroids, although they have no brains or nodes, have a certain sense of touch, sight and smell. Each of the starfish's arms can perceive the world around itself. That is, each of its arms has sensors.
When one of the arms "smells" something good to eat, what it does is "cut off" the energy supply to the rest of the arms and begin to pull the body toward the food source.
Starfish are not fish, they are echinoderms, as are sea urchins and cucumbers. And they have no blood, but a vascular water system.
They are well known for the reefs, which is nothing more than the "shell" of a dead coral, joined to that of its neighbor with what make up huge multicolored masses.
They create those maritime paradises, full of colors and a beautiful image for the human being, but it is not as beautiful for the small creatures that float around.
A coral reef can be understood as a wall of mouths.
Each small polyp is a predator that can project its stomach towards its neighbors - if they get too close - and devour them right there.
In addition, you can create a slime net to catch the little creatures that float around or hunt them with their tentacles and bring them closer to your stomach.
For humans they do not represent a danger due to our size, but even so, in ancient times they sank because of the skeletons of corals - calcium carbonate - that destroy the wooden hulls.
So dangerous were coral reefs for ships that, in the 1830s, the Beagle, with Charles Darwin on board, was sent to the Pacific to map the coral islands.