As an expert in the field of biology, I can provide you with an informative answer regarding organisms that do not possess brains. The brain, as we understand it in higher organisms, is a central organ that coordinates and processes information from the body. However, not all organisms have a brain in the traditional sense. Let's delve into the details:

Step 1: English Answer

Plants do not have brains. They have a different system for growth and response to stimuli, which is based on hormones and cellular signaling rather than a centralized nervous system. Plants communicate and respond to their environment through chemical signals and electrical impulses, but they do not have a brain or a central processing unit like animals.

Fungi, as mentioned, do not have brains. Fungi are a separate kingdom from plants and animals, and they have a unique way of processing information and responding to their surroundings. They have a network of filaments called mycelium, which can coordinate activities, but this is not comparable to a brain.

Single-celled organisms such as bacteria and protozoa do not have brains. These organisms are simple and perform all their life functions within one cell. They do not have specialized organs, including a brain.

In the animal kingdom, the presence of a brain is more common, but not universal.
All vertebrates, animals with a backbone, have a brain. This includes mammals, birds, reptiles, amphibians, and fish. The brain in these animals is a key part of the central nervous system.

However, among invertebrates, which are animals without a backbone, the situation is more varied. While many invertebrates have some form of nervous system, not all have a brain in the way that vertebrates do. Here are some examples:

- Starfish (Sea stars) have a simple nervous system but no brain. They have a nerve ring at the center of each arm, which helps them coordinate movement and response to stimuli.
- Jellyfish also lack a brain. They have a nerve net that allows them to respond to their environment, but it is a diffuse system without a central brain.
- Sponges are among the simplest of invertebrates and do not have a nervous system or brain. They filter water through their bodies to obtain food and oxygen, and they do not have specialized sensory or nervous structures.
- Coral is not an individual organism but a colony of tiny living creatures called polyps. Corals do not have a centralized brain or nervous system.
- Sea anemones are similar to corals in that they are simple and do not have a brain. They have a simple internal structure with a mouth and a single opening that serves as both the entrance for food and the exit for waste, but no brain.
- Sea squirts (Tunicates) have a simple nervous system but are often cited as lacking a brain. They have a diffuse network of nerves, but no centralized brain structure.

It's important to note that the absence of a brain does not mean these organisms are incapable of complex behaviors. Many invertebrates have sophisticated ways of interacting with their environment, even without a brain. Their nervous systems, while different from those of vertebrates, allow them to respond to stimuli, find food, avoid predators, and reproduce.

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No fungi have brains. Some multicellular animals do not have brains. All vertebrates have brains. But some invertebrates like starfish, jellyfish, sponges, corals, sea anemone, sea squirts don't have brains.read more >>