Echolocation is a process that permits dolphins to send out sound waves that when they hit an object, are bounced back, allowing them to identify the location, shape, and size of such object.

The amount of time it takes for the sound waves to come back help them to determine the distance, as it takes longer the sound waves to return when there is more distance between the dolphin and that given object.

The first person to look at echolocation thoroughly and to document the findings was Jacque-Yves Cousteau. He wrote about it in a book published in 1953 called The Silent World.

Echolocation or biosonar is the ability of some animals to locate objects through sound waves, that is, sounds. Many animals, including odontocete cetaceans and some bats, make use of echolocation to orient themselves and detect prey.

The process of evolution of dolphins gave them this ability that allowed them to survive in the aquatic environment. In water, the sound waves travel 4.5 times faster than in the air, so echolocation is the perfect resource that facilitates their survival.

WHY DOLPHINS USE ECHOLOCATION?

Dolphins need echolocation to navigate, locate prey, hunt, protect themselves from predators in murky waters or where there is no sunlight and to communicate. In fact, in deep dark waters, their sense of sight is almost nil, but they do not need it because they can detect and chase fast prey through the emission of sounds.

Most odontocete cetaceans can emit very high-frequency sounds. In this sense, the frequencies vary according to the species, but there are general characteristics in all dolphins. For example, they always communicate with low-frequency signals, which include whistling or chirping; But they emit high frequencies when using echolocation. The sounds vary according to the circumstances and the purpose.

Dolphins need echolocation to navigate, locate prey, hunt, and protect themselves.

HOW DO ECHOLOCATION WORKS?

First, is necessary to know that dolphins are devoid of vocal cords, so they do not have a “voice” like that of humans. Instead, they generate sounds through other internal structures.

Step number 1: Generate sounds.

Dolphins produce sounds from the nasal air sacs, the blowhole, the larynx, the lungs, and the melon; This latter is an organ located in the upper inner area of ​​the head filled with low-density lipids.

First, the dolphin opens the blowhole to make an inhalation and the nasal air sacs swell as the air enters the lungs. Then the dolphin exhales: the air resonates in the nasal sacs and comes out with pressure through the blowhole. Vibrations occur in the larynx, and the nasal air sacs deflate.

For echolocation, dolphins emit ultrasounds called “clicks” by pushing air between the phonic lips of the nasal passages. When these lips open and close, the surrounding tissues vibrate and produce sound waves.

The passage of air through the respiratory cavities generates the sounds.

Step number 2: Amplify sounds.

The Dolphins have an organ in the head, called melon, that allows the transmission of the sound waves.

The melon concentrates the pulsations that the dolphin emits and sends them forward. The primary “function” of this organ is to group sounds into beams and produce and amplify the resonance.

Once the emission is released forward, the sound waves bounce back in the objects that are in the water.

Step number 3: Reception and interpretation of sounds.

A part of the signal bounces back in the objects and returns as an echo to the dolphin. Their brain receives the sound waves in the form of nerve impulses, and the dolphin can interpret this echo.

The receiver of the returning sound waves is in the lower jaw, and the teeth of dolphins work like antennas to receive the signals. It is a very complex adaptation vital for their survival.

The intensity, pitch, and time that it takes the echo to return to the dolphin provide information about the target, such as its size, shape, composition, position, distance, and direction. Based on this, the dolphin builds an image of its environment and the object.

Echolocation has been studied in bottlenose dolphins (Tursiops truncatus), although there are still underlying aspects that are not entirely understood. For now, scientists see echolocation as a learning opportunity to create new communication technologies in some areas of human life.

DOLPHIN ECHOLOCATION

What is known is that dolphins have the ability through echolocation to emit sounds with a frequency of 120 kHz and humans, with excellent hearing, can hear sounds with frequencies ranging from 20 Hz to 20 kHz. Even dogs and cats that have amazing hearing capabilities do not compare to dolphins. Dogs hear up to 45 kHz, and cats up to 65 kHz.

However, high-frequency sounds don’t travel very far in the water while Low-frequency sounds have more energy and can reach greater distances. Most of the time, dolphins will get the best results with echolocation when the object is from 16 to 656 feet from them.

Excessive noise in the environment should be upsetting for dolphins and can cause them to lose their hearing over time. It can also disorient them and disrupt their navigation systems.

References

Kathleen Dudzinski, Toni Frohoff. Dolphin Mysteries: Unlocking the Secrets of Communication. Yale University Press, 2014.

Jeanette A. Thomas, Cynthia F. Moss, Marianne Vater. Echolocation in Bats and Dolphins. University of Chicago Press, 2004

Whitlow W.L. Au. The Sonar of Dolphins. Springer Science & Business Media, 2012.

https://link.springer.com/chapter/10.1007/978-1-4612-1150-1_9#page-1

https://seaworld.org/en/animal-info/animal-infobooks/bottlenose-dolphins/communication-and-echolocation

While attempting to photograph any wild animal is often a difficult undertaking. Photographing wild dolphins presents it’s own individual challenges. If you happen to be planning a boat trip or a swim with the dolphins, there are a few things you need to keep in mind to make sure you take advantage of every photographic opportunity.

The most important thing to remember is to let the dolphins approach you. Dolphins are very social creatures and seem to react favorably to interaction with humans, if allowed to do so on their own terms.

Your photographs will be much better if the dolphin is actually in an inquisitive mode. Nobody wants to see photos of dolphins fleeing in panic.

If you’re attempting to shoot the dolphins from a boat, odds are you’re going to end up in rough water at some point.

Remember to brace yourself and your camera equipment so neither you nor your equipment ends up in the water. The motion of the boat, as well as the speed at which dolphins can travel, will require using a fairly high shutter speed on your camera. ASA/ISO 100 or 200 film will help alleviate some of the graininess that will result from the higher shutter setting but achieving a balance between these two comes with practice. A lens filter will help to reduce glare and a motor drive is extremely helpful when the dolphins are extremely active.

A telephoto lens will be necessary as its often difficult to get to close to the dolphins from the boat. The best type of camera for this type of photography is a Single Lens Reflex (SRL) and either a Nikon or Canon body.

If you’re actually lucky enough to participate in a dolphin swim, you’ll want to use wide angle lenses. Dolphins, even the younger ones, are fairly large. and a lens with a narrow angle of view will require more distance to make sure the entire dolphin is included in the frame. Wide angles lenses will provide more control and flexibility with the sharpness and color saturation of the imagen

Obviously, if you are swimming with dolphins, a water proof camera will be needed, but there are many options for that which are not necessarily expensive cameras. You can find a waterproof housing for your own camera, or there are several waterproof cameras now, even digital, at really affordable prices.

If you need a camera for your trip, the recommended stores where I have purchase a cameras online with great results are:

They both have a great selection and prices and they both have great information to help you choose the right camera for your budget. Don’t get too excited! Quite often the experience of just being in the water with the dolphins will be so exhilarating that even the most talented photographer is reduced to simply snapping away with no thought to the actual composition of the photograph.

If you take the time to get in close with a wide angle lens, the resulting photograph will make the subject in the foreground appear disproportionately larger than the background. This technique can produce an amazing image. Changing angles on the dolphin can also add personality to your images. A picture of the dolphin in a side profile as well as one that captures the entire length of the creature can create an interesting collage of finished photographs.

When photographing dolphins, the use of a light meter is essential. Dolphins usually swim close to the surface which will require accurate settings of surrounding light conditions. The use of a strobe as fill lighting will also bring contrast to the dolphins features.

Regardless of how close you can actually get to the dolphin, using a few of the above techniques should guarantee an interesting array of photographs. If you’re patient and take the time to do a little practicing before your trip, you should be able to capture an extremely amazing opportunity with ease.

The Boto dolphin (Inia geoffrensis), inhabits the Amazon basin and part of the Orinoco river basin, so it has a wide variety of species available to eat, although it prefers fish since it feeds on more than 43 types, including the feared piranhas. Complementary this dolphin also eats crabs and turtles.

It consumes about 2.5% of its body weight daily.

There are several species of herring, being the most common the Atlantic Herring.

This species is registered as the most available fish in the ocean by the Guinness book of records, which makes them at the same time, the most hunted species by dolphins.

The Atlantic Herring dwells on both sides of the Atlantic.

The food that dolphins eat is different for each species.
While some dolphins eat fishes like herring, cod or mackerel, some others eat squids or other cephalopods.

Even more, large dolphins like killer whales, eat marine mammals like seals or sea lions and sometimes even turtles.

Usually, the amount of fish that they eat depends on the kind of fish that they hunt. While mackerels or herrings have a lot of fat, squids do not have much fat, therefore, to get the energy required for their activities, dolphins have to eat more of the latter.

On average, a dolphin with a weight of 200 – 250 Kg will eat between 10 Kg to 25 Kg of fish every day.

Usually, to hunt fish, some species of dolphins use a method called herding which is a cooperative hunting performed by a pod where some of them surround a school of fish to compress them as much as possible, while some others take turns to eat through the compacted school of fish.

Another method is corralling where dolphins take fish to shallow waters where they cannot escape.

Some species catch larger fish by hitting them with their tails to stun them and in the case of killer whales, they

Therefore the question about what do dolphins eat has to be answered for every species in particular.

In this video, you can watch a pod of dolphins working together to feed themselves and using the technique called herding to catch the fish as they surround the school of fish, and then some of them take turns to eat.

In the video, you can learn more about What do dolphins eat.

Dolphins use several methods to get their food. Fish and squid are the main sources of food for most dolphin species, and they hunt in group cooperatively to catch them.

One method called herding consist that a group of dolphins encircles a school of fish to gather them as close as possible and after that one or two take turns to swim from the bottom of the school to have the largest amount of fish possible on each pass.

It is important that they go from bottom to top because if they were from side to side, the school of fish would probably disperse.

The second method is called corralling, which is performed taking fish to shallow waters where dolphins can just capture them.

Some species are even more specialized or with unique techniques to catch fish or other particular prey that only they consume, like killer whales hunting seals, for example.