Friday, May 13, 2022

How Big Is A Fish Brain

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The Size Of A Fish Brain


Ok, so most fish have physically smaller brains than human beings, which is in part because they tend to be comparatively small. Yes, there are some pretty big fish out there, but when compared to human beings, most are smaller.

So, it does make sense that fish brains are on average comparatively smaller than that of humans. On that same note, even if one considers the size difference between a fish and a human, fish do have smaller brains.

However, this does not mean that they are stupid, not at all. When it comes to the weight and size of the brain compared to other vertebrates, fish do have smaller brains, about a fifteenth of the comparative size of a bird or small mammal. That being said, sharks and other such fish have about the same brain-to-body ratio as many birds and small mammals.

The question of how big is a fish brain? is indeed relatively impossible to answer. There are different sizes of fish and they can vary greatly from very small sardines to massive tuna and sharks.

Therefore, there is no average size brain for a fish. That being said, fish brains are quite small, but this does not mean that they are brainless. There are indeed some fish that are known to have a good memory, cognitive abilities, the ability to construct things, and other such skills too.

Lets now go over some examples which illustrate that fish do possess a certain level of intelligence.

Are Cleaning Interactions Not Cognitively Demanding

Our data on brain sizes relative to body mass and on the relative size of specific brain areas mostly yield the conclusion that on such basic anatomical levels the brain of cleaning wrasse species and of L. dimidiatus in particular are organized in similar ways as closely related non cleaning species. A possible exception is the size of the diencephalon relative to the rest of the brain in L. dimidiatus. When we discuss these findings, it is important to consider two potential explanations. First, that cleaning interactions are not that cognitively demanding, second that cleaner wrasse have adjusted to the cognitive challenges by a reorganization of the brain rather than by increasing its size. Both ideas have their potential merits.

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Do Goldfish Have Brains And How Intelligent Are They Really

You might be please to hear that the answer is yes goldfish do have brains.

This diagram shows the location of a goldfishs brain. As you can see, the brain is located at the top of the head, above the fishs eyes, at the front of its spine.

And not only do goldfish have brains, theyre actually quite intelligent animals.

Its myth that goldfish have bad memories. They can actually remember things for several months, at least.

Goldfish can also be trained to do tricks and behave in certain ways. For instance, pressing a button to get food. Goldfish wouldnt be able to do this if they didnt have a brain and at least a basic form of memory.

Goldfish are also socially intelligent. They are able to recognise and remember individuals including humans and they change their behavior around mates, potential mates and fish they know to be aggressive.

Brain Mass Relative To Body Mass In The Measured Specimens

BIG BRAIN: Big Brain Fish

shows the bivariate plot of logarithmized brain mass vs. body mass values in the measured wrasse specimens . Overall, the slope of the brain vs. body mass regression was estimated as 0.338±0.061, and the species did significantly differ = 0.0004). Gomphosus varius individuals had a relative larger brain than the other species . Halichoeres was the genus with the relatively smallest brains but the difference to species other than Gomphosus was not statistically significant in a PostHoc test.

Brain mass vs. body mass in 22 wrasse specimens.

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What Is The Most Humane Way To Kill A Fish Intended For Eating

All fish that are caught for eating must be handled carefully to reduce stress and humanely killed as soon as possible after capture. Humane killing requires that the fish is stunned before being bled out.

Fish should remain in water until immediately prior to stunning. There are two methods that can be used to stun fish caught by hand: percussive stunning and spiking .

Percussive stunning involves a forceful and accurate blow to the head with a blunt instrument. The force required will depend on the size of the fish. The blow should be aimed just above the eyes to impact on the brain. The effectiveness of the stun should be checked and another blow applied if the fish is not unconscious.

Spiking involves driving a sharp spike into the brain of the fish. The spike should be placed in a position to penetrate the brain of the fish and then pushed quickly and firmly into the skull. The impact of the spike should produce immediate unconsciousness. The spike should then be moved from side to side to destroy the brain. Visit for a detailed description of this process.

After stunning or spiking, the fish should be bled out by cutting the gill rakers or, with larger fish, a main artery.

Mechanism Of Action Of Alcohol In The Brain

When we consume alcohol, it reaches our bloodstream after some time and then reaches our brain as blood circulates through the body. In the brain, it binds to a variety of receptors of neurotransmitters, leading to diverse effects. Mainly, it binds to receptors of GABA, an inhibitory neurotransmitter, and decreases the responsiveness of nerve cells. This type of overall reduction in brain activity is called central nervous system depression.

In addition, it also causes a similar inhibitory action in the spinal cord and the lower part of the brain, called the brain stem. It does this by interfering with the receptors of a neurotransmitter called glycine. Together, these lead to an overall relaxed state of being. The muscle movements of the person slow down, pupils relax, breathing slows, and there may be confusion and dizziness. Of these, the most notable effect is a lowering of social inhibition, allowing us to behave in ways that we typically wouldnt.

In addition to inhibitory action, alcohol also reduces the action of excitatory neurons, creating a sedative effect.

Alcohol acts on the cerebellum, a part of the brain that helps to coordinate movements, resulting in a decreased ability to coordinate muscle movements while walking, talking, etc.

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Jellyfish Circulate Nutrients And Gases Through Diffusion

Before answering this question, we should understand exactly what a heart does. It essentially pumps blood around the body so that an animals cells can draw oxygen and nutrients from the blood and emit soluble waste such as carbon dioxide. However, what is special about the anatomy of jellyfish is the thickness of the outer layer, known as the ectoderm. It is only a few cells thick, so oxygen simply diffuses into the jellyfish body.

Jellyfish also have a very rudimentary digestive system, in which simple nutrients merely diffuse into the rest of the body. None of these oxygen and nutrient diffusion processes, due to the simplicity of the jellyfish anatomy, require a powerful pump like the heart to allow them to penetrate the entire organism.

Natures first draft of a nervous system might be simple, but it still works. Considered among the first even to have a nervous system, the cnidarians nerve nets reveal the evolutionary origins that led to later, more complicated nervous systems like ours!

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Jellyfish are truly fascinating creatures that manage to survive without many of the organs we now consider vital, and their bodies are well suited to survive the conditions of the endless blue, drifting across the vast oceans, displaying their beauty for all to seeat a safe distance!

Fish’s Brain Size Influenced By Habitat

Catch and Cook BIG OL’ FISH HEAD!!
University of Guelph
This is the first known study to connect habitat with varying brain size in a single lake fish population. The finding may provide clues about how fish and other creatures will respond to mounting environmental stressors from pollution to climate change. Researchers say bigger brains contain more neurons, and more connections among them, that lend its owner cognitive and behavioral smarts that may help it adapt to new environments.

The busier the neighbourhood, the bigger the brain — at least for pumpkinseed sunfish, according to a pioneering study by University of Guelph biologists.

Brains of sunfish living in more complex shoreline habitats are larger than those of their counterparts in simpler open water, according to the study published recently in Proceedings of the Royal Society B.

This is the first known study to connect habitat with varying brain size in a single lake fish population, said lead author PhD student Caleb Axelrod, adding that the finding may provide clues about how fish and other creatures will respond to mounting environmental stressors from pollution to climate change.

He authored the paper with integrative biology professors Frédéric Laberge and Beren Robinson.

For ecologists, brain size matters.

Scientists believe a bigger brain contains more neurons, and more connections among them, that lend its owner cognitive and behavioural smarts that may help it adapt to new environments.

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How Jellyfish Rule The Seas Without A Brain

They have no brain and are mostly water, yet jellies have plenty of superpowers.

When we think of dangerous animals, a bag of water without a brain may not seem like it should be on the list. But if ocean bathers hear jellyfish! theyll stand at attention like meerkats, because jellies can pack a wallop.

Often gorgeous and often dangerous, jellyfish are a slippery mass of contradictions. Before the summer fades, we take a look at their squishy superpowers.

Do Starfish Have Bones

Although starfish are invertebrates, they do have a kind of skeleton. The bodies of starfish are composed of calcium carbonate plates, known as ossicles. These form the endoskeleton, which takes on a variety of forms such as spines and granules. They have a primitive nervous system, but not a brain.

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The Verdict Is In But Will Our Oceanic Friends Ever Get The Same Legal Protections As Land Animals

Hakai MagazineThis article is from Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at

When Culum Brown was a young boy, he and his grandmother frequented a park near her home in Melbourne, Australia. He was fascinated by the parks large ornamental pond wriggling with goldfish, mosquitofish, and loaches. Brown would walk the perimeter of the pond, peering into the translucent shallows to gaze at the fish. One day, he and his grandmother arrived at the park and discovered that the pond had been drainedsomething the parks department apparently did every few years. Heaps of fish flapped upon the exposed bed, suffocating in the sun.

Brown raced from one trash can to another, searching through them and collecting whatever discarded containers he could findmostly plastic soda bottles. He filled the bottles at drinking fountains and corralled several fish into each one. He pushed other stranded fish toward regions of the pond where some water remained. I was frantic, running around like a lunatic, trying to save these animals, recalls Brown, who is now a marine biologist at Macquarie University in Sydney. Ultimately, he managed to rescue hundreds of fish, about 60 of which he adopted. Some of them lived in his home aquariums for more than 10 years.



How Do Starfish Reproduce Asexually


Asexual reproduction in starfish takes place by fission or through autotomy of arms. In fission, the central disc breaks into two pieces and each portion then regenerates the missing parts. Although almost all sea stars can regenerate their limbs, only a select few sea star species are able to reproduce in these ways.

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Do Goldfish Have Brains Its Not A Stupid Question

People often talk about having the memory of a goldfish to mean theyre forgetful, so its understandable that people think goldfish are unintelligent and wonder whether goldfish have brains at all.

And its certainly not a silly question. Did you know that not all animals do have brains?

For instance, starfish have a complex nervous system, but not a centralised brain. While jellyfish dont have a brain or a central nervous system. If these aquatic creatures dont have brains, maybe goldfish dont either? Lets find out

How Big Are Fish Brains

While goldfish do have brains, their brains are not exactly huge!

A goldfishs brain is about the same size as its eye. When you compare that to a human brain, youll realise that proportional to their body size the goldfish brain is really quite small.

This is the same for most types of fish. Most fish have brains that are about 1/15th the size of a similarly-sized mammal or bird.

In fact, it is a fish that holds the record for the lowest ratio of brain size to body mass. The Bony-eared Assfish not only has a very unfortunate name, it also has the smallest brain of any animal with a spine .

There are some exceptions though. Elephantfish and sharks actually have quite large brains for their body size about the same as birds and marsupials.

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Inside The Brain Of A Crayfish

University of Virginia
Neurophysiology researchers commonly use crustaceans to try to gain basic understanding of the nervous systems of creatures in general, and, wherever possible, for extrapolating what they find to a basic understanding of the much more complex human brain. All animals, from single-celled amoebas to humans, use similar cellular processes to interpret their olfactory environment.

Voyage to the bottom of the sea, or simply look along the bottom of a clear stream and you may spy lobsters or crayfish waving their antennae. Look closer, and you will see them feeling around with their legs and flicking their antennules the small, paired sets of miniature feelers at the top of their heads between the long antennae.

Both are used for sensing the environment. The long antennae are used for getting a physical feel of an area, such as the contours of a crevice. The smaller antennules are there to both help the creature smell for food or mates or dangerous predators and also to sense motion in the water that also could indicate the presence of food, a fling or danger. The legs also have receptors that detect chemical signatures, preferably those emanating from a nice hunk of dead fish.

Im interested in understanding how these senses are combined and interpreted in the brain of these animals. My question is, how does the brain detect, integrate and use co-joined but dissimilar sensory inputs?

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Are There Any Benefits To The Ostrich Having A Smaller Brain

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According to anew study comparing about 2062 bird species, in highly variable environments, birds tend to have either large or small brains relative to their body size.

According to the study, big brains in animals can help them quickly adapt to unexpected environmental changes. However, some birds like ostriches just dont need them. Their small brains allow them to utilize ecological strategies that are not available to other big-brained animals. Generally, instead of solely relying on their brains to survive, small-brained animals like ostriches tend to have bigger bodies, consume readily available food, and produce a large number of offspring . Their high reproductive rates allow them to quickly recover from high mortality rates due to their challenging conditions.

Another advantage is that a small brain demands less energy compared to a big brain. Because ostriches tend to consume a high fibrous diet that requires a large gut to digest, a lot of their energy is diverted to the gut. Given that brains are as energy-demanding as guts, having a smaller brain actually benefits the ostrich as its able to easily maintain the required energy levels to both organs.

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How Is The Brain Size Of A Fish Measured

Their brain size is measured in comparison to body size and weight. Some fish do break this rule. The most notable two are the shark and mormyrid. The mormyrid is any of several species of slimy, freshwater African fishes. They are soft-rayed, bony fish with a small mouth and eyes, forked tail fins, and abdominal pelvic fins. Both of these, when compared to their body weight, have massive brains.

Bone Physiology And Pathology

Zebrafish have been used as model organisms for bone metabolism, tissue turnover, and resorbing activity. These processes are largely evolutionary conserved. They have been used to study osteogenesis , evaluating differentiation, matrix deposition activity, and cross-talk of skeletal cells, to create and isolate mutants modeling human bone diseases, and test new chemical compounds for the ability to revert bone defects. The larvae can be used to follow new osteoblast formation during bone development. They start mineralising bone elements as early as 4 days post fertilisation. Recently, adult zebrafish are being used to study complex age related bone diseases such as osteoporosis and osteogenesis imperfecta. The scales of zebrafish function as a protective external layer and are little bony plates made by osteoblasts. These exoskeletal structures are formed by bone matrix depositing osteoblasts and are remodeled by osteoclasts. The scales also act as the main calcium storage of the fish. They can be cultured ex-vivo in a multi-well plate, which allows manipulation with drugs and even screening for new drugs that could change bone metabolism .

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