Dolphins can vary greatly in terms of their size and can range from 4 ft. long (Maui’s dolphin) all the way up to 30 ft. long (thekiller whale) and weigh anywhere from less than 100 pounds to as much as 22, 000 pounds.
Currently there are about 40 known species of dolphin in existence today, however some of the earliest known species of dolphin can be traced back as far as 10 million years.
Dolphins are known for being extremely intelligent and playful animals.
They are also known to be some of the most agile and athletic species known to inhabit the ocean.
In fact some species of dolphin have been known to swim as deep as 1000 ft, jump as high as 30 feet out of the water and travel as fast as 25 miles per hour.
When it comes to diet dolphins are known to eat a variety of different foods which can vary greatly depending on the dolphins species, hunting methods, social structure anatomical features (i.e. overall size and teeth).
One of the most determinant factors involved in a dolphins diet is the species it belongs to with smaller species often eating small prey that is easy to swallow and digest while a few of the larger species are able to consume much larger prey.
In terms of diet some of the most popular types of foods dolphins are known to hunt for include fish, cod, herring, mackerel, squid, plankton, krill, cephalopods and crustaceans while larger dolphin species such as the killer whale and false killer whale (the killer whale actually belongs to the dolphin family) can be seen consuming larger prey such as large squid, sea lions, walruses, seals, sharks, seabirds, turtles and even large whales.
As a species dolphins are extremely social creatures and spend will their time together on a number of different activities including hunting for food.
By hunting as a group these marine mammals maximize their ability to successfully capture their prey while avoiding being injured or attacked.
During hunting expeditions dolphins can often be seen traveling together in pods consisting of 2 – 30 dolphins using a number of sophisticated strategies and group oriented hunting techniques to stun, isolate and capture their prey.
One technique dolphins are known to use (known as a bait ball) to capture fish involves a group of dolphins swimming around a pool of fish in a circle, which forces the fish to form into a tightly knit ball.
Once the fish are gathered together and unable to escape the dolphins will then taking turns darting in and picking off the helpless fish off one by one.
Another popular technique dolphins use when hunting for prey is known as corralling.
Corralling is a technique that is commonly used by dolphins that live in or around shallow waters and rivers (coastal dolphins) and requires the dolphins to chase the fish into shallow waters or rivers banks where they can get the fish into a small narrow corner against a mud bank, ship or wall so that the fish become trapped and have no way to escape while the dolphins move in and attack them.
While hunting fish some dolphins will also use their tail to hit and smack the fish which temporarily stuns and paralyzes them long enough to allow the dolphins to attack them as they lay defenseless.
In areas where light is low or completely absent dolphins can rely on echolocation to find their prey.
By using echolocation dolphins can determine where an object is, how far it is, whether it is above or below them, how fast it is moving, what direction its moving in and whether the object is hallow or dense.
This not only helps dolphins locate food, it also helps them navigate the often pitch black ocean.
While there is no exact estimate on how much food a dolphin is likely to consume on a daily basis most dolphins will consume between 4% – 10% of their body-weight in food on a day-to-day basis.
Dolphins can vary greatly in size from the smallest dolphin (Maui’s dolphin) measuring in at around 4 ft. and weighing around 88 pounds to the massive killer whale which can measure in at 30 ft. and weigh more than 22,000 pounds.
Most dolphins have streamlined bodies which are designed for agility and fast swimming.
The size and shape of their body can vary from one species to the next.
The long-beaked common dolphin for example has a very slim streamlined body with a long beaked compared to the killer whale that has a stockier build and lacks a beak.
The size and shape of a dolphins teeth along with its jaw strength play a major role in determining whether or not these marine mammals swallow their prey whole or break it down for easier consumption and can have some affect on the types of prey they hunt.
When it comes to color and skin tone dolphins can vary greatly from one species to the next.
Colors may include black, dark grey, light grey, bluish, brown, yellow, pink and white with some species being a solid color while others may have spots or lines across sections of their body.
In order to swim dolphin’s use their tail for propulsion while their fins help them stabilize, turn, roll and navigate through the water.
Dolphins (along with all toothed whales) are born with a single blowhole used for breathing compared to baleen whales which are born with two blowholes.
Unlike humans and land mammals dolphins do not breathe through the mouth as their trachea (air passage) and esophagus (food passage) are not connected.
This separation may make it easier for dolphins to consume food underwater without the risk of ingesting water into their lungs.
Having a blowhole on the top of their head also makes it easier for them breathe during resting periods as they do not have to consistently lift their mouth above the water to take in air.
Unlike whales most dolphins do not make huge migrations trips.
Some dolphins will migrate due to seasonal changes, but they usually don’t travel nearly as far as some whale species.
Dolphins typically prefer tropical climates, however they can be found swimming in colder waters as well, such as the killer whale.
Most dolphins belong to one of two ecosystems.
Coastal dolphins are typically smaller in size and prefer to stay near the coastline in shallow waters.
These dolphins make up the majority of the dolphin species.
The other type of dolphins are known as off shore dolphins which prefer to live further out at sea and away from the coastline.
While coastal dolphins prefer to stay closer to the coastline they are often limited in their travel range given their coastal habitat while the larger off shore dolphins are more likely to migrate during seasonal changes or when their food migrates to a new area.
Social Structure and Communication
Dolphins communicate with one another using sound, body language and visual signals.
While Dolphins may not form words as humans do they are able to talk and speak to one another in their own language.
In fact while humans communicate by using their tongues and vocal cords to create individual words dolphins communicate with one another using their blowhole by creating a series of clicks and whistles in a variety of different pitches, tonalities and frequencies.
These differences in pitch and frequency allow dolphins to communicate a variety of things to one another such as an interest in mating, that they have found nearby food sources, that there is danger in the area, that they want to play, how they feel and a host of other things related to their survival or desires.
These differences also make it easier for dolphins to keep track of each other and observe who is speaking in a group since each dolphin communicates in a slightly different tone and frequency.
These variations in dolphin clicks and whistles work in the same way that a human voice does since we all use the same words but talk in different tones and speeds which makes it easy for us to identify who is speaking regardless of whether or not we can see that person.
The language these marine mammals use can change dramatically depending on the activity they are performing and the number of dolphins within their pod.
For example the variation of clicks and whistles a female dolphin may use to call for her child is likely to be very different from a dolphin that is letting his/her pod know that a predator is nearby.
Aside from having a highly developed language and social structure dolphins are also considered extremely intelligent and are able to perform complex tasks, complete puzzles and memorize specific orders that are given to them by their trainers.
Dolphins have been used at marine parks to perform jumps, flips and other acrobatic feats and by the military to help them discover mines and locate people lost at sea.
Dolphins have even been observed protecting people from sharks and leading people back to land, without being trained to do so.
The language dolphins use to communicate is considered so complex and intelligent that the marine biologist and scientists that study these marine mammals hope to one day be able to develop technology that will enable them to communicate directly with these animals using their own language.
The possibility of talking to another species in our own backyard has been a driving force in pushing our understanding of the dolphins language forward.
One scientist was even quoted saying,
We are so interested in finding life on another planet when there is a highly intelligent species already on earth that we may one day be able to talk to.
Aside from using language to vocally communicate with one another dolphins also communicate by using body language and visual signals such as rubbing against another dolphin, leaping out of the water, tail slapping, fin slapping or charging at one another when they want to play, communicate a desire, alert other dolphins in their pod or show aggression towards another dolphin.
By combining vocal language with physical gestures dolphins are able to develop close emotional relationships with one another and share bonds with each other that are just as strong as those of humans.
To sum everything up dolphins are able to communicate with one another in a complex language, but they’re also able to perform other actions to communicate with each other using touch and visual gestures allowing dolphins to communicate and talk in various ways at a very deep emotional and intellectual level.
The average gestation period (the period between conception and birth) for a female dolphin can range from 11 – 17 months.
Dolphins have also been known to have intercourse during periods where they are not in their estrous cycle.
During mating season male dolphins can become increasingly aggressive and competitive and may even fight other males or herd off the female dolphin to limit her chances of becoming impregnated by other males.
Some male dolphins will even create factions where they’ll fight and fend off competing factions trying to mate with their females.
For dolphins that do begin mating and bear offspring female dolphins usually mature between the ages of 5 – 14, while males usually mature between the ages of 9 – 14, however as with their gestation period sexually maturity can range from 5 – 21 years depending on the species.
Female dolphins typically produce a single offspring every 2 – 6 years and will often raise their young for several years after they are born.
During this time the female dolphins will nurture their young and feed them milk from their nipples until the child is able to hunt and survive on its own.
The nursing period may last from 6 months up to 2 years, however most species appear to be self sufficient within the first 12 months.
Life expectancy can vary depending on the dolphin species with estimates ranging from 25 – 80 years for healthy dolphins.
Lifestyle, habitat, endangered status, predators, social structure and other factors can play a large role in how long a dolphin or dolphin pod is likely to live.
As a species dolphins are extremely intelligent.
In fact dolphins are well-known for their amazingly complex social structure and language.
These marine mammals are able to communicate with one another using various high-frequency clicks and whistles, which they use during social interactions to inform other dolphins of important information such as when they have spotted a predator, when they have found a nearby food source, when they’re angry with one another, when they have a desire to mate and how they feel as well as various other interests they want to share with the dolphins around them.
Some dolphin species have even been refereed to as the wolves of their sea due to the fact that they live, socialize, play, defend and hunt together like a pack of wolves.
Other species have been identified as having their own complex culture much like our human culture or those of elephants, which has a hierarchy of leaders, followers and decision makers with a diversity of interest and talents based on the dolphins species and pod.
Aside from learning about dolphins by watching them interact with one another and on their own in their natural habitat scientists, marine biologist and trainers have spent decades communicating with dolphins directly teaching them to perform complex tasks and tricks.
These marine mammals have been observed at marine parks performing flips and other acrobatic tricks when directed by their trainers and have also been used by the military to assist military personnel in locating bombs in the ocean and finding individuals who are lost at sea.
In addition to performing these amazing tasks dolphins are also capable of self recognition.
When observing their own reflection in the mirror dolphins are able to identify objects that are placed on their body.
Marine biologists that study these mammals believe that self recognition strongly indicates a highly intellectual species as most animal species are not capable of self recognition.
This capability of self-awareness has only been observed in a handful of species including humans, bonobos, monkeys, gorillas, elephants and dolphins.
Due to the development and complexity of dolphin language researchers hope to one day be able to develop technology that will allow us to understand and communicate with these amazing animals.
Being able to communicate directly with dolphins would be a huge advancement in our understanding of other species and if possible would be one of the first examples of vocally communicating with another species that can talk back to us.
These are only a few of the unique characteristics scientists have gathered about the dolphin species in order to understand their level of intelligence and social complexity.
Conscious Breathing and Sleep
Unlike most mammals that breathe unconsciously and shut down when they rest dolphins have a unique way of dealing with rest that allows them to remain semi conscious so they don’t fall completely asleep.
There are a number of reasons why dolphins don’t sleep, or rather why they never fall completely asleep.
The primary purpose of remaining semi conscious is for survival purposes.
To better understand this it is important to point out that one contrasting difference between land animals and marine mammals such as dolphins (as well as whales and porpoises) is the fact that dolphins live, survive and thrive in the ocean rather than living on safe land.
Because dolphins are ocean bearing mammals they must always be aware of their surroundings otherwise they could drown or fall prey to predators.
If a dolphin were to fall completely asleep while in the ocean it would risk the possibility of drowning (the same way most land mammals such as humans would drown if they fell asleep in the water), therefore dolphins have developed a way to keep their brain partially active and alert while they are at rest so that they don’t become unconscious and drown or get eaten by a predator.
To make breathing easier dolphins generally prefer to remain at or near the surface of the water when resting so that they can easily come up for air when it is necessary.
Having their blowhole located on the top of the head also makes it easier to take in oxygen without having to lift their head completely above the water or exert unnecessary energy when resting.
Although dolphins never fall completely asleep half of their brain does shut down when they are tired allowing them to rest and regain their energy.
In addition to always remaining partially conscious dolphins also have complete control over their breathing system so that they don’t have to worry about sneezing or coughing underwater, which could accidentally open up the air passage and allow water to come into the dolphins lungs when it is submerged or drastically reduce the dolphins oxygen supply.
Whether they are hunting food, searching the ocean, resting or playing with one another dolphins have to always be conscious of how much oxygen they have left before they need to resurface.
By having a specially adapted circulatory system, lungs and heart and by being able to constantly monitor their oxygen supply and turn off non-essential functions dolphins can hold their breath for significantly longer than a human and maximize the quality of oxygen in each breath they take.
Lastly by always being partially alert and awake dolphins are able to quickly react to threats or predators looking to hunt, attack and/or harm them.
Unlike humans and land animals that require additional time to wake up and stretch before beginning the day dolphins are able to quickly snap into alertness and react to survival situations without the need for an extended waking period.
Not only are dolphins capable of maintaining partial awareness when they rest.
This characteristic is present in all cetacean species which includes whales, dolphins and porpoises.
Dolphin/Shark Prey Relationship
Although hunting sharks is not a common characteristic among the cetacean species there are a few species of dolphin that are known to eat sharks for lunch.
Most dolphins are not equipped to fight or attack sharks as they lack the size, strength and coordination necessary to bring a shark down, however species such as the killer whale and “potentially” the false killer whale may hunt, attack, kill and eat sharks when other forms of prey are not enough for their dieting needs.
While the killer whale and false killer whale are often referred to as a “whales” these two species are actually part of the dolphin family.
The “whale” part of their name comes from the fact that these dolphins are the largest of the dolphin species and are as big as some species of whale.
The “killer” part of their name comes from the fact that these dolphin are known to hunt, attack and eat other marine mammals such as marine birds, seals, sea lions, whales, dolphins, porpoises and polar bears as well as various fish and sharks.
In addition to being able to kill fish, sharks and other mammals on their own these dolphins are often found hunting together as a pack in order to maximize their success rates and are even referred to as the wolves of the sea due to their family like structure and hunting methods.
When searching for their prey these dolphins use stealthy aggressive hunting techniques as a cohesive group in order to isolate, immobilize, capture and consume their prey.
Aside from working as a team killer whales are also equipped with echolocation which allows them to identify objects in their surrounding, even when in pitch black environments.
Echolocation allows killer whales to identify the size, location, distance, movement and density of an object in their surrounding location allowing them to be better hunters and navigate the ocean more effectively.
As stated earlier though most species of dolphin do not attack or kill sharks.
This is largely due to their smaller size, strength, social structure and lack of useful teeth, which would be necessary for both defending themselves and tearing the flesh of their prey apart.
Other species may work together as a team to defend themselves and their children from sharks and in severe cases may be able to ram the shark or cause serious injuries to them, however they do not generally attack sharks without a cause or need to defend themselves.
When it comes to food most species of dolphin consume small foods such as fish, crustaceans, squid and a variety of other small sea creatures that they are able to hunt and easily consume without the fear of being hunted or attacked by the foods they are hunting.
Note: In addition to having the widest diet of all dolphins the killer whale is also known as an apex predator, meaning it is able to hunt for without the fear of being hunted itself. In other words killer whales do not have any known natural predators.
dolphins have enjoyed millions of years of inhabitants on earth and continue to reproduce and prosper at a steady pace in many parts of the world.
With that said there are a few species of dolphin that are considered critically endangered and are at risk of facing possible extinction.
While not always the case dolphins that live either in freshwater environments or close to the coastline are often at a greater risk of becoming endangered than dolphins that live further out to sea largely due to the fact that coastline dolphins are in constant interaction with people, boats, fishing crews, construction work and pollution.
Some of the most common reasons for why these dolphins have become endangered is due to excessive hunting, water pollution, noise pollution (from sonar and loud man-made sounds) the construction of dams, bridges, industrial environments, landscape reconstruction, waterway reconstruction, excessive fishing (which deplete food stocks) and fishing equipment, which can cause dolphins to get caught in fishing nets and other fishing equipment.
While many of these non direct attacks on dolphins can lead to accidental deaths one of the more deliberate practices that lead to dolphin deaths includes hunting or poaching dolphins.
In these cases hunters may hunt dolphins for their meat, which they sell to meat markets and disturbers that sell dolphin meat to various food chains, restaurants, supermarkets and meat markets.
While dolphin hunting has caused much less severe consequences then generations of whale hunting the act of hunting these marine mammals combined with industrialization are some of the leading causes of why some of these dolphins end up endangered.
To aid in preventing dolphins from being killed various laws and regulations have been put into place making it illegal to hunt dolphins and forcing fishing boats to take more cautious efforts when fishing.
Even with these regulations some individuals and countries still choose the hunt dolphins today.
Although hunting continues to occur there are still many species of dolphin that are thriving today and the likelihood of the entire species becoming extinct is extremely low, however there are several species which may face extinction if stringent regulations aren’t put into place to prevent both accidental killings and deliberate hunting of this important species.
Overall dolphins are a very resilient species and their ancestors existed well before humans from an evolutionary standpoint, so these marine mammals are well equipped with the ability to adapt to changing environments assuming no major changes occur over a relatively short period of time.
Dolphins are a protected species.
In fact dolphins, porpoises and whales are all protected marine mammals and belong to the cetacean family.
In the past these marine mammals were hunted for their blubber and meat which was used to produces oils, food, lubricants and various other goods.
Over the decades mass killings led to various species of whale becoming endangered.
Although whales were hunted significantly more than dolphins they too were occasionally hunted for their meat or used for crab bait.
As various cetacean species began to decline in numbers numerous governments and organizations began to create rules and regulations which were later followed by laws, steep fines and possible imprisonment against those that continued to hunt and kill cetaceans for commercial uses.
In 1946 the IWC imposed a number of regulations in order to monitor the whaling industry and minimize the number of unnecessary whaling activities and in 1986 new laws were passed to prohibit all non-essential whaling activities among the countries that signed into the agreement.
Although hunting whales, dolphins and porpoises is considered illegal there are still countries that hunt these marine mammals for their meat which can be found sold at certain supermarkets, meat markets and restaurants in various parts of the world.
One stipulation to the rule that has been taken advantage of in order to continue hunting these marine mammals is a law that allows some whales to be killed for research data.
The purpose of killing whales for research is supposed to be used to help track migration patterns, keep tabs on the health of certain whale species and use the data to improve the safety, life expectancy and health of various whale species, however some whaling companies have used this law as a loophole to continue the practice of whaling in order to sell their meat for a profit.
After the whale has been captured the organization then states that they must sell the meat in order to dispose of it in the best manner.
This practice has led various organizations and anti whaling groups to lobby against this practice and push for new laws to further inhibit any form of whaling behavior.
On the other end dolphins are also sometimes hunted and killed.
They may be hunted by fisherman looking to reduce the competition they face from dolphins continually hunting the same fish that the fisherman are hunting.
Their meat may also be mixed in with tuna or other fish foods or used for crab bait in order to lure in more crabs.
As with anti whaling practices organizations and groups are lobbying together to create stronger laws and steeper fines for those that continue to hunt these marine mammals.
Although dolphins are being killed by some fisherman in most cases dolphin killings are accidental as dolphins sometimes run into fishing nets thinking that they’ve found an easy group of prey to attack.
Being a marine mammal dolphins need oxygen in order to survive and those that get caught in fishing nets are sometimes unable to rise to the surface in order to take in oxygen and end up drowning.
The rules, regulations and laws that have been created have led to mass declines in the number of cetaceans that are being hunted and killed, however it is likely that there will always be some level of hunting going on regardless of the laws that are passed.