There are many studies out there that compare the size of brains from one living thing to the next. What has been found is that the size of the brain for a human and a dolphin are almost the same. This is based on information that shows the evolution of the cetacean brain over a period of more than 47 million years!

Such studies have given experts information about the large size of the brain for toothed whales. Some of these species have abilities that have only previously been seen to exist in some of the Great Apes as well as humans. Now they have also been observed with some of the species of dolphins.

Brain of Pacific white-sided dolphin / Author: Tranletuha.

There are studies that show dolphins have the ability to recognize who they are when they see their reflection in a mirror. They are also able to communicate using symbol based programs and through concepts that are abstract in nature. Some researchers believe that the large size of their brain is what allows such intelligence to occur.

Yet what continues to be a huge mystery to the experts is the evolution of the brain over time. One of the largest fossil studies that has ever been conducted has been done by Lori Marino has several of her colleagues from Emory University in Atlanta. The study spanned 4 years looking over various collections in different museums.

The team used 66 different fossilized cetacean skulls that they found. Using CT scans, they were able to document the size of each of the brains. They were also able to document the body mass through the bones found at the base of each skull.

This study also included looking at similar data already collected on 144 cetacean skulls. This resulted in a total of 210 samples being looked at, with 62 species and 37 different families being represented in that total of samples. Find the EQ, or Encephalization Quotient, of each one was the purpose of collecting such data.

If you aren’t familiar with EQ, it is a representation of the ratio of brain to body mass. The scale works like this:

Large brain size – EQ greater than 1

Average brain size = EQ of 1

Smaller than average brain size = EQ less than 1

The largest of all creatures is humans with an EQ of 7. There have been two significant points in the evolution of cetacean that the EQ showed a significant jump. The first dates back about 35 million years ago. There were dramatic changes to the EQ as well as to changes in body size.

There are studies that indicate the development of larger brains was the result of the evolution for echolocation. This is the use of high frequency sounds that can be picked up as they echo off of various objects. Then the animals are able to interpret a variety of information from that occurrence.

It is believed the second dramatic increase in brain size occurred about 15 million years ago in the Delphinoidea super family. This includes narwhales, belugas, dolphins, and porpoises. The information from fossil records suggests that these increases were significantly more than that of humans or great apes.

The findings of this study are believed to be one of the few that have helped us to gather such information from the fossil records. Such research is time consuming but it is also very important as well as interesting. If you are interested in reading more about the research this team has done, it will be in The Anatomical Record, December issue.

Source: http://dsc.discovery.com/news/briefs/20041108/dolphin.html

Adult bottlenose dolphins have a length ranging from 10 to 14 feet long and weight 330 to 440 pounds. The body length and weight vary according to the region where they live and the quality and availability of food. There are specimens up to 1,100 pounds, but they are not common.

The hole on the top of the dolphin is the blowhole.

Dolphins breathe by getting air through the blowhole, which can empty and refill the lungs of a dolphin in one-fifth of a second.

The blow is explosive and the air reach speeds of up to one hundred miles per hour.

A nerve mechanism alert the dolphin when the blowhole is out of the water, so it can blow out the air and breathe in again.

Strong muscles close the blowhole when dolphins dive into the water to avoid drowning.

This question is paramount because they are similar in the water and many times people confuses them. Even more, some people sometimes use the word dolphin and porpoise interchangeably. However, this is a mistake, as dolphins and porpoises are in fact different animals.

While both are mammals and nurse their calves similarly, both have lungs and breathe air; they have several significant differences.

Taxonomically both are cetaceans and members of the Odontoceti suborder, but they belong to different families. Porpoises are part of the Phocoenidae family while dolphins belong to the Dolphinae family.

Physically, porpoises are smaller than dolphins, reaching up to seven feet long while dolphins reach up to ten.

Porpoises have small rounded heads while most dolphin species have a round bulbous in the head.

The dorsal fin of porpoises is different than the dorsal fin of dolphins, while the former have a triangle shaped fin, the dolphin’s fin is slightly curved backward.

Regarding their behavior, porpoises are shy creatures, which usually do not approach boats while dolphins show less fear, approaching more often to people.

Bottlenose dolphins are probably one of the best-known species of animals. They have a length of around 10 to 14 feet and a streamlined body with a large fin at the top. Their skin is gray and smooth without long hair like most mammals.

Some look small, and others are much larger and heavier, since their range is between 150 and 650 kilograms, with males having larger body dimensions than women, so there is sexual dimorphism.

One of the characteristics of bottlenose dolphins is their thick and notorious snout that give them their odd colloquial name.

Other features of bottlenose dolphins are the flippers and their powerful caudal fin.