Red starfish in blue ocean water Red starfish in blue ocean water

The World of Brain-Less Wonders

Aren’t you curious about how animals work just like us? How do you know if an organism is actually an animal? Well, this time, I found some exciting and jaw-dropping facts about the brainless wonders of the world. Wait. I’m talking about animals with no brains. I always heard that all things need brains to live. It may sound unimaginable but, some animals do not have any brains, yet they survive just fine! 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.

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.

what animals don't have brains
– Source: Pixabay

1. Starfish

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 hearts. In addition to these, they have extremely brilliant nervous systems, which are formed by the nervous plexus.

what animals don't have brains
– Source: Pixabay

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.

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.

what animals don't have brains
– Source: Pixabay

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.

3. Jellyfish

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.

what animals don't have brains
– Source: Pixabay

All these actions are functioning with the help of a network of sensory nerves.

4. Corals

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 non-living beings.

what animals don't have brains
– Source: Pixabay

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.

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 being filtered.

what animals don't have brains
– Source: Pixabay

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 8000 species of sea sponges, and they are different in terms of fresh water and salty water.

6. Sea Anemones

Sea anemones have no brain, no heart, and no organs. They are like coral and sometimes resemble plants, but they live 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.

what animals don't have brains
– Source: Pixabay

Like other sea animals, they also have tentacles with stinging properties to protect themselves from predators.

7. Clams

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.

what animals don't have brains
– Source: Pixabay

They are bivalve and, hence, can survive in both salt water and fresh water. Their nervous system is pretty strong, and it helps them to feel things and react to them. They are very popular across the globe as they are found literally everywhere.

So, Finally, How do They Function Without a Brain?

Isn’t it amazing that there are creatures on this planet who live without brains? Humans rely a lot on the brain and tend to use it everywhere. While animals like jellyfish, coral, and starfish don’t require brains, they have some sort of specialized cells that may allow them to respond and sense the environment. To help them navigate the world, some animals have simple nervous systems that have no centralized brain.

Usually, animals that do not have brains are aquatic, and the underlying reason is their morphology, which they 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 allows them to survive without a brain.

Last Updated on April 15, 2024 by Arnab Nandi


Anushree Khandelwal
  1. The facts about the animals that doesn’t have brain is very interesting as we have learned that brains control every body part. It’s really extraordinary how well those animals perform their activities like they have brains. This post is very knowledgeable.

  2. “Interesting read! I always assumed that all living creatures had brains of some sort. It’s amazing to discover that some animals have evolved to function without one. I wonder if these brainless organisms have unique ways of solving problems or if their behavior is purely instinctual. Great job shedding light on this lesser-known aspect of the animal kingdom!”

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