How do you know if an organism is actually an animal? Well if you can classify them into any of the following six categories, then it is actually an animal, and the categories include mammals, birds, reptiles, amphibians, fish, and invertebrates.
Now when we see different animals, some have one brain, some have no brain and some even have multiple brains and this article is all about knowing the animal brains.
1. What’s in a Brain?
If you ask scientifically, then the brain is just clustered neurons. It is a group of nerve cells that pretty much control the functions of your body. So, this clearly implies that any animal that does not have a brain is extremely simple.
They have very rudimentary anatomical and biological existence. Indeed some of them might even be immobile.
I’m sure it almost feels impossible to imagine a living being other than plants that can actually live and thrive without a brain. Plus compared to plants, animals are quite complex. Even then there are animals that do not have a brain.
2. How can Animals Function without a Brain?
Usually, the animals that do not have brains are aquatic, and the underlying reason is their morphology which they have acquired from their ancestors. But how do they actually survive?
So, to understand this we have to first keep in mind that all animals adapt to their lives and ecosystems. They figure out ways to exist, eat, reproduce, and excrete.
The key to survival is basically the removal of all the complex parts of the body which require a lot of brain usage; so simplicity is what lets them survive without a brain.
Just like the gadgets that we use, they do not have real brains. They also have some kind of sensors just like these animals have sensors to detect danger or food. Due to the simple mechanisms, they survive easily even without a brain.
3. What Animals Don’t Have Brains?
Starfish is an invertebrate and belongs to the Asteroida order. It lives in the deep sea and can have anywhere between five to fifty arms, depending upon the species. The arms are their life literally as they help them to reproduce, excrete, and hunt.
Along with brains they also do not have a heart. In place of these, they have extremely brilliant nervous systems, formed of nervous plexus.
These send signals to the different parts of the body and work as a distributed brain, which helps them to take in stimuli and produce a reaction accordingly.
3.2. Sea Cucumber
Sea cucumbers have a very functional oral cavity in place of the brain that actually functions like one. As is it surrounded by the neural tissue which helps in sending signals to the mouth and testicles.
To feed themselves they move on the seafloor looking for food like algae and other decomposing material.
Due to the way that they consume food, it is highly likely for them to actually eat some mud and sand, which is then filtered out of their food like a sieve. Usually, animals like turtles, crabs, and fishes eat sea cucumbers.
Jellyfish are translucent and they are unique animals that do not have brains. They are immobile and usually live in one spot throughout their lives.
They move with the help of ocean currents and squirt water for forward movement. This ability to squirt water helps them to move away from predators.
They also have tentacles which serve as the main protection feature as they are capable of releasing toxic substances that can even kill their predators.
The entire functioning of all these actions happens with the help of a network of sensory nerves.
You will be surprised to know that corals not only have no brains but also they have no nervous system or heart. Their structural formation is such that it consists of thousands of polyps that have tentacles and these have nerve endings.
Corals when they form reefs actually look like formations of rock or some plants and sometimes even like they are some non-living beings.
They are of a variety of types and usually live in colonies. The polyps are what help these organisms to catch prey and understand their surrounding environment.
3.5. Sea Sponges
Another strikingly surprising creature is sea sponges, these also have no brains plus no internal organs. Since they are immobile they eat the tiny organisms and other particles around the water they are in, after filtering it.
They have an extremely long life and some sea schools claim that they can live for more than 100 years. In total, there are more than 5000 species of sea sponges and they are different for fresh water and salty water.
3.6. Sea Anemones
Sea anemones have no brain, no heart, and no organs. They are like coral and sometimes resemble plants but they are living and actually grow by attaching themselves to a rock or sand substrate.
They have a very basic and primitive nervous system that helps them to react to the stimuli that they receive. It also helps these creatures in maintaining their vital balance.
Like other sea animals, they also have tentacles with stinging properties to protect themselves from predators.
Clams belong to the same family as oysters and scallops. They can open and close their shells.
These are mollusks which have a compressed body inside a shell. They have almost everything but a brain like stomach, heart, mouth, kidneys, and even a nervous system.
They are bivalve and, hence can survive in both salt water and fresh water. Their nervous system is pretty strong and helps them to feel things along with reacting to them.
They are very popular across the globe as they are found literally everywhere.