The Cetacean Cerebellum And Cerebrum
We have data on the cerebellum mass of 101 adult cetaceans, of which 66 were from Delphinidae, 19 were from the PZIP group, 7 were from the Phocoenidae-Monodontidae group, and 9 were Mysticeti 6 additional subadult mysticetes were also included in the data . After adjusting for log10 body mass, there was no significant difference in mean log10 cerebellum mass between Mysticeti and the PZIP group.
Cerebellum mass and body mass among individual adult cetaceans from all of our taxonomic groups. The upper regression line shows data for the family Delphinidae with 95% confidence intervals. The lower regression line shows combined data for the Balaenidae, Balaenopteroidea, and PZIP groups. Data for the Phocoenidae-Monodontidae group were plotted, but not included in the Delphinidae regression.
Cerebellum mass and ROB mass among individual adult cetaceans from all of our taxonomic groups. The regression line shows data for Delphinoidea with 95% confidence intervals. Data for the PZIP, Balaenopteroidea, and Balaenidae groups are also plotted, but not included in the regression. As the slope is nearly equal to 1, the relationship between cerebellum mass and the ROB is nearly isometric for the delphinoids.
The Livers Role In Digestion Of Food
The liver plays a significant role in processing the nutrients from the food and absorbing it. The liver generates bile, which is then sent to the small intestine for digestion and absorption of fat-soluble vitamins and fat contents of food.
The nutrients absorbed in the small intestine go to the liver first. Then dolphins can send these nutrients to the rest of the body or be processed for storage.
The dolphin liver also helps to perform several functions in the body. For example, the liver of dolphins plays a significant role in blood clotting.
Cooperative Feeding Tool Use And Social Learning
Whales and dolphins use exceptionally clever methods to find and catch their prey, and these reveal great levels of cooperation, intelligence and social learning.
Bottlenose dolphins in Australia have developed quite a range of tools and methods to aid mealtimes. One group, known as the spongers grab a sea-sponge and dive down to the seabed with it. Holding the sponges tightly in their mouths, they then poke them into the sandy seabed, disturbing fish in hiding. The fish emerge, the sponge is dropped, the meal is eaten, and the tool picked up for further foraging. The sponges protect the dolphins noses from scuffs, scrapes and stings, in the same way as we would protect our hands with gloves when gardening or clearing rubbish from a beach.
Other bottlenose dolphins living in Shark Bay, Australia, carry large conch shells in their mouths when fishing it looks a bit like they are playing an instrument. The dolphin fills the shell and then visits the surface to shake it so that the seawater drains out, leaving small fish trapped in the bottom. One deft flick of his head and the dolphin has earned himself a tasty snack. The knowledge of these extraordinary and creative fishing methods is passed from dolphin to dolphin.
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The Key Differences Between Dolphin Brain Vs Human Brain
The greatest differences between human brains and dolphin brains are their overall size, hippocampus, and cerebral cortex. Dolphin brains are larger than human brains, weighing 1,600 grams compared to the human brain that weighs 1,300 grams.
Human brains have a highly developed prefrontal cortex, the largest of any primate, but the dolphins prefrontal cortex is small and underdeveloped. Lastly, humans have a larger hippocampus area in the brain compared with dolphins.
These are the three greatest differences in the human brain and dolphin brain, and they can help explain the disparity in intelligence between the two species.
Variance In Brain Sizes
Body size accounts for 80â90% of the variance in brain size, between species, and a relationship described by an allometric equation: the regression of the logarithms of brain size on body size. The distance of a species from the regression line is a measure of its encephalization . The scales are logarithmic, distance, or residual, is an encephalization quotient , the ratio of actual brain size to expected brain size. Encephalization is a characteristic of a species.
Rules for brain size relates to the number brain neurons have varied in evolution, then not all mammalian brains are necessarily built as larger or smaller versions of a same plan, with proportionately larger or smaller numbers of neurons. Similarly sized brains, such as a cow or chimpanzee, might in that scenario contain very different numbers of neurons, just as a very large cetacean brain might contain fewer neurons than a gorilla brain. Size comparison between the human brain and non-primate brains, larger or smaller, might simply be inadequate and uninformative â and our view of the human brain as outlier, a special oddity, may have been based on the mistaken assumption that all brains are made the same .
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Dolphin Brain Vs Human Brain: What Are The Differences
Humans and dolphins are often compared to one another since it was discovered that dolphins possess a high level of intelligence. Dolphins are mammals capable of problem-solving and engaging in highly social behaviors. That has made many people, including scientists, wonder: what are the differences between a dolphin brain vs human brain?
These brains are very different in some ways but also similar in others. Were going to show you how our brains are different from dolphin brains and the impact that these differences have upon each species. For the sake of our comparison, we will be using the brain of a bottlenose dolphin as a contrast to the average human brain. That particular species has been studied most thoroughly, so data about them is more widely available.
Dolphin Brain Vs Human Brain: Size
Dolphins brains are larger than humans brains. The average dolphin brain weighs about 1,600g and the average human brain weighs about 1,300 grams.
However, when we consider the size of a human brain vs a dolphin brain, its not enough to say that the bigger brain is the more intelligent creature. In fact, humans have a larger brain than dolphins relative to their body size. Even though dolphins have the largest brain-to-body weight ratio, they still fall behind humans in terms of intelligence.
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Dolphin Brain Vs Human Brain: Encephalization Quotient
Human brains have a higher encephalization quotient than dolphin brains. The encephalization quotient is the ratio between the real and predicted brain mass of an animal-based on its body size.
For human beings, the encephalization quotient is higher than any other animal at 6.56. Dolphins are not too far behind at 4.0 EQ.
However, some studies suggest that the EQ might not be the best way to measure cognitive abilities across non-human primates, meaning that measure might not be as significant as earlier studies have indicated. That is not to say that its not an important or insightful form of measurement.
The Difference Between Human And Cetacean Brains
You see, what I found after twelve years of work with dolphins is that the limits are not in them, the limits are in us. So I had to go away and find out, who am I? Whats this all about? Dr John Lily
What is intelligence? How do you measure it? For us, we tend to only accept intelligence displayed on the same evolutionary wavelength as our own think little blue men with lasers and spaceships. We think of intelligence as the harnessing of technology, and the ability to think abstractly about striving to achieve growth and progress. Perhaps it is this that has made it easy for humans to reject the concept of intelligence in other species. But what if a species didnt need technology to thrive rather, what if that technology was in-built within that species?
To help us get to grips with this idea of other intelligent species, we take a look at the brains of one of the potentially smartest groups of animals on our planet, cetaceans.
Side by side you can see the difference between a human and dolphin brain
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Dolphins’ Big Brains Evolved In Spurts
By Maggie Mckee
Dolphins have evolved surprisingly big brains over the last 47 million years, according to the largest fossil study ever done on the animals. The growth which occurred in two spurts may shed light on how humans became so brainy.
Dolphins are famously bright, performing mental feats few other animals can, such as recognising themselves in mirrors. That intelligence is probably due to their exceptionally large brains some dolphin species boast brain-to-body mass ratios second only to humans. But how they evolved such big brains has been a mystery.
Now, a trio of researchers led by biologist Lori Marino at Emory University in Atlanta, Georgia, US, has tracked how dolphins evolved their big brains using the fossil record. After four years of scouring museum collections, the team turned up 66 fossilised skulls of dolphin ancestors adding to only five studied previously.
They probed the specimens brain sizes with computed tomography scans and estimated the animals body masses by analysing the size of bones around the base of the skulls.
What About The Size
As with determining their weight, determining the overall size of dolphins can be a difficult task because there are numerous species, and each species of dolphin has characteristics that make them unique from other dolphin species.
However, we can look at a couple of dolphin species to give you a general idea of these differences in regards to size and weight.
The smallest known dolphin is Mauis dolphin, known to grow to lengths of around 5 1/2 ft. long at full maturity and weigh slightly over 100 lbs.
This dolphin is a rare dolphin species that can be found near the shore of North Island in New Zealand. In comparison, the largest known dolphin is the killer whale, which can grow up to 30 ft. long and weigh as much as 12,000 lbs.
Unlike Mauis dolphin, the killer whale can be found throughout various oceans worldwide.
While not always the case, size can directly influence where dolphins can live throughout the world.
For example, some smaller species of dolphins can be found traveling in and around coastal waters where they are less likely to face threats from potential predators.
In contrast, larger dolphins may venture out further into the offshore ocean, far from coastal waters.
Predators for the dolphin species may include killer whales and sharks, and yes, killer whales hunt other dolphin species for food.
Size can also play a role in the dolphins ability to stay warm in cold climates.
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What Do Dolphins Eat
The dolphins diet depends on the environment they live in and the time of the year. However, most dolphins will eat various fish, sea plants and crustacean animals.
For example, bottlenose dolphins living near the Scotland region love to eat salmon fish during the spring and summer months. However, when the salmon is scarce during the winter, they tend to shift their preference and hunt down fish like herring and mackerel.
The bottlenose dolphins that live on other sides of the world will eat fishes, like mullet, mackerel, catfish, and many tropical fishes. On the other hand, the amazon river dolphins are known to feed on more than 40 different fish species. These dolphins also love to hunt the freshwater crustaceans.
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The orcas, the biggest member of the dolphin family, generally hunt much larger prey. Like sea lions, they live on seabirds and other marine mammals. The orcas diet mostly depends on the available food and the hunting techniques that they have learned from their elders.
Sharing is a good thing to do!
Northern & Southern Right Whale Dolphin
These dolphins are recognizable by their lack of a dorsal fin, short curved flippers, and well-defined beaks. Southern Right Whale Dolphins are uniquely colored, often with white bellies and black backs, although some can be completely black or white. northern right whale dolphins look just the same but are typically black.
Both of these dolphins enjoy deep, cold to temperate oceanic waters, but they live in opposite hemispheres of the earth. As their names suggest, the northern right whale dolphin lives in the Arctic waters, while the southern right whale dolphin lives in the Antarctic waters.
Northern and southern right whale dolphins share the ninth spot in our lineup at an average length of 9.8 feet and a lower weight of about 250 pounds.
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The Size Of A Walnut Does Equine Brain Size Matter
November 5, 2019 by
There seem to be quite a few social media posts about the equine brain of late and thats no bad thing.
In some ways, the brain is simply the latest part of the equine anatomy to come under the spot light. Its being subject to statements about welfare, training and psychology and thats definitely a good thing
However, I want to add something to this equine brain discussion. I just happened to run in to it when I went down a research rabbit hole a couple of years back.
We often hear how brain size is not directly linked to an individuals intelligence. At the same time, a relatively large brain is said to signify intelligence in humans, while that of the horse, popularly said to be the size of a walnut, is said to account for their lack of intelligence.
Vintage anatomy print showing relatively small size of equine brain to body size.
This falls down once we look at elephants, which have relatively small brains yet are pretty cluey.
In horses, innovative behaviors without evolutionary basis are often used as a measure of intelligence . Leaving behaviour-based measurement methods aside for the moment, lets ask: how do we figure out if theres an association between different brain sizes and intelligence levels?
© All text copyright of the author, Jane Clothier, www.thehorsesback.com. No reproduction of partial or entire text without permission. Sharing the link back to this page is fine. Please contact me for more information. Thank you!
How Much Do Dolphins Weigh
Dolphins have been a mystery and a source of fascination for humanity for thousands of years.
They may belong to the more commonly known family Delphinidae, including all oceanic dolphins, or the family Platanistidae, including the river dolphins.
More than 40 species of dolphins live throughout the worlds oceans and rivers.
These mammals vary greatly in size, ranging from 4 to 30 feet and their weight ranging from 88 lbs. up to 22,000 pounds.
The largest dolphin families are referred to as whales.
These dolphins live off the coast of New Zealand, and the average adult weight of these small mammals is 88 to 132 pounds .
They have an average adult length of 3.8 to 5.3 feet .
Other small dolphins include Heavisides dolphins, which weigh 132 to 154 pounds and are about 5.6 feet long when they reach adulthood, and acrobatic spinner dolphins, which weigh 130 to 170 pounds and measure about 6.6 feet in length as adults.
Another small dolphin is the Indus river dolphin as an adult, this dolphin weighs about 150 to 200 pounds and measures 7.5 to 8.5 feet long.
The Atlantic spotted dolphin, which as an adult weighs 200 to 315 pounds and measures 5 to 7.5 feet in length, is another dolphin in the middle-weight class.
Finally, the largest dolphin is the killer whale or orca.
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Baleen whales, which filter tiny shrimp called krill and similar food, have smaller brains relative to their size than pack hunters like dolphins and orcas.
Blue whales, bowhead whales have small brains. They also seem to move around in loose aggregations, Shultz added.
They dont have long-term, stable relationships. They dont have lots of complex behaviors.
Shultz and her colleagues didnt directly study whales, but instead dug up every scientific study they could find on whale and dolphin behavior. They found tons of it.
Killer whales live in societies of multiple generations and what people have been able to show recently is that older individuals are basically storehouses of information and they pass on this information to younger individuals in times of hardship, Shultz said.
For instance, they know where to go when the fish disappear from favored hunting grounds.
And they communicate in very sophisticated ways. Whale songs, for instance, come in dialects.
Theres good evidence that sperm whales have fads, Shultz said.
Whats really attractive in one year isnt attractive in another year. It is very much like our culture and our fashion. One population invents a new song and it passes on to other populations.
Orcas, dolphins and other cetaceans hunt in packs, form alliances, cooperate with other species including humans, babysit one anothers offspring and they eat rich, varied diets.
And they dont just use those names in greeting.
Total Brain Size Differences Relative To Body Size
We categorized our data from each taxonomic family into 1 of 5 groups based on how the individual data points clustered with brain-body size regression analyses. The species and families included in these 5 groups are listed in Table 2. In general, we based the groups in our data analyses on the taxonomy of cetaceans presented by the Taxonomy Committee of the Society for Marine Mammalogy . Brain to body mass and body length relations in our sample of adult cetaceans represented both odontocetes and mysticetes . Odontocetes were grouped along 3 regression lines . The family Delphinidae had larger brains relative to body size, followed by Phocoenidae and Monodontidae, and then by a group of all other odontocetes these other odontocetes come from the superfamily Physeteroidea , family Ziphiidae, superfamily Inioidea , family Lipotidae, and family Platanistidae. Hereafter, this group of other odontocetes will be referred to as the PZIP group. Animals of the superfamily Balaenopteroidea, which includes the families Balaenopteridae and Eschrichtiidae, had a smaller relative brain size than the 3 odontocete groups but had a larger relative brain size than Balaenidae .
Total number of individuals for which we have brain mass data and number of species included from each taxonomic family
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