Dolphins are active predators that have a carnivorous diet. Their eating habits are flexible so that they can adapt perfectly to the habitat where they live.

Although they have small teeth, they do not use them to chew the food but only to hold the prey. What they do is, once the prey is in their control firmly hold by those teeth, they swallow it whole starting with the head. If the prey is a large animal, then they tear it by shaking or crushing their body so that it breaks into smaller pieces.

The stomach of these cetaceans has several compartments that make digestion a quick process. The daily total food intake varies according to the species, but they do not feed abundantly. For example, a bottlenose dolphin (Tursiops truncatus) consumes between 4 and 5 percent of its weight per day.

Dolphins spend plenty of time finding food every day, and some species can consume up to 30 pounds of fish per day as adults. They migrate and move long distances to find food, although if they have enough supply where they reside, and the temperature of the water is also acceptable, they probably won’t migrate.

Dolphins do not use their teeth to chew the food but only to hold the prey.

FAVORITE PREY

They consume a variety of bony fish, crustaceans, and cephalopods. Individuals living near the coast regularly feed on fish and benthic invertebrates, while those who stay in high seas prefer to eat squid and fish as well.

Specifically, their favorite prey includes:
– Atlantic mackerel
– Herring
– Mullet
– Cod
– Squid
– Octopus
– Shrimp

Orcas (Orcinus orca) are a separate case because their diet includes more than small fish. They are used to hunt other marine mammals such as walruses, sea lions, and seals, as well as penguins, sea birds, and even small baleen whales.

Some reports indicate that deep-sea fish remains have been found in the stomach of some dolphins, pointing out that they may be able to dive up to 500 meters deep to search for food.

HUNTING METHODS

Dolphins use various strategies to catch their food, but they are usually related to group hunting:

HERDING.

When a pod of these cetaceans locates a school of fish large enough, they start to surround their prey to reduce the area of ​​dispersion. Imagine a compact group of thousands of fish going from side to side to avoid a set of predators. When the prey is already disoriented, the dolphins take turns entering the fish school from below and begin feeding themselves. Some others stay on the outer perimeter to avoid the fish to disperse.

Herding is one of the most common methods of feeding that they use; This involves a pod working as a unit to get a school of fish to curl up into a tight ball. Then, they take turns to rush through and plow the center of that ball, eating all they can in the process.

CORRALING.

Other times, a pod goes to the coasts or the sandbanks to facilitate their task as these areas offer a great variety of fish and it is easier to catch them. Dolphins sometimes corral fish in shallow waters so they cannot escape.

Dolphins learned to feed following fishing vessels. Bottlenose dolphins are the species that practices this more often, and it involves following trawl nets to feed on discarded fish and or those thrown back into the water by the fishers.

They do not always hunt in groups. If necessary, dolphins also look for food individually. Orcas and other species herd their prey to the coasts or places where they will not escape and sometimes wait patiently until the victim makes a mistake and can catch them. There are some videos of orcas practically getting half of their body on the sand to the catch seals that feel safe in the seashore, in a move that has to be perfectly coordinated with the ocean waves.

Sometimes dolphins beat the prey with their tails until they come out of the water and they catch them in the air with their mouths.

Recently a particular behavior was discovered in bottlenose dolphins that inhabit the west of Australia: when looking for food in rocky areas, females protect their snout using a marine sponge; Just when they intend to swallow the prey they release the sponge and eat. This unusual but sophisticated behavior is exclusive to females and their offspring.

OTHER DOLPHIN FEEDING METHODS.

The concept of cooperative feeding involves driving the schools of fish to the shallow areas of the water. Sometimes, this is to the coast, or it could be to some natural barrier or even a subgroup of the dolphins making such function. Other species drive prey into muddy banks so that they can simply catch them.

There are certain species of dolphins that use their flukes to stun their prey hitting them, and while the victims are still disoriented, they will feed on them.

What is fascinating too is that in some locations the dolphins have learned to help the fishermen drive the fish into their nets. The payoff for dolphins is that they get to feed on the leftover fish that get out of the nets.

Large pods use circular cooperative feeding. They divide into subgroups and then form circles surrounding schools of fish this way and continue to reduce the overall size of that circle before they take part in consuming them.

Something very similar is the crossing cooperative feeding; This involves dolphins moving in a cross pattern with groups of them swimming in different directions, allowing the fish to be in the middle of the routes that dolphins have created. Such strategy is usually a good one to use around rocky shores and in shallow areas of small bays.

Dolphins are intelligent, so they have the option to create different methods that fit their feeding needs. They have been seen mixing two or more of the mentioned feeding strategies into one session to get results. The ability to create such variations with ease and to build new formations is fascinating. The level of cooperation it takes among the dolphins in the pod is also noted.

FEEDING DOLPHINS?

When meeting dolphins, either in aquariums or in areas that these cetaceans visit, humans can provide them with food, but this action is not good for them.

Researchers point out that the fact that dolphins get quickly accustomed to being fed causing them to lose their natural hunting ability. If you visit an area with ​​dolphins, do not feed them!

References

bioexpedition.com/dolphin-feeding/

Animals, a visual encyclopedia. Smithsonian. Dorling Kindersley, 2012.

Alan Rauch. Dolphin. Reaktion Books, 2013

https://en.wikipedia.org/wiki/Dolphin#Feeding

]]> https://www.dolphins-world.com/dolphin-communication/ Tue, 25 Apr 2017 23:08:30 +0000 http://www.dolphins-world.com/?p=132 Dolphin Language and Communication

Communication, strictly meaning, involves the transmission and feedback of coded messages. However, the complexity of the communication processes seems to be exclusive to the human race.

Despite this, it is clear that dolphins have a sophisticated communication system which is the reason for their success against their predators. In short, dolphins survive because they communicate with each other and this allows them to organize and cooperate to increase their probabilities of survival.

HOW DO DOLPHINS COMMUNICATE?

Dolphins communicate through the emission and reception of sounds; Each dolphin develops its distinctive sound since the first years of life. All individuals produce a unique sound, which is different to the others so they can fully identify each other.

Dolphins emit two types of vocal sounds: continuous tone and burst-pulsed sounds.

But, how do they produce these sounds? While dolphins are devoid of vocal cords, they emit sounds through their larynx, in the region of the nasal air sacs. These sounds do not mean that dolphins have a voice, but there is a tissue in the nasal area that has structures that project in the duct. When the air passes through that section, the tissue vibrates, and so the sound is produced.

Dolphins emit two types of vocal sounds: continuous tone and burst-pulsed sounds. The first type includes whistles, squeaks and some species of squeals. They are “frequency modulated sounds” because dolphins modify the tone of the sound, this is, it can rise and fall over time. The burst-pulsed sounds are recognized by the superposition of sound waves and refer to the “clicks,” produced successively at regular intervals.

WHERE, WHEN, WHAT

Different emissions, different context. Dolphins can make sounds to interact socially: when they separate from their peers, when they are excited, when alarmed or just when they feel happy. The sound depends on the situation. Lost dolphins have been observed to produce whistles frantically in an attempt to call their companions, and individuals of some species emit pulsating sounds if they become excited or angry; Apparently, this is intended to make known their emotional state to other dolphins.

Sometimes bottlenose dolphins (Tursiops truncatus) produce a blast that invites other individuals to play, as a way of informing them that they are in a good mood and want to have fun with them. Very high pulsating sounds are used during aggressive encounters to call other dolphins, and others direct to the genital area of ​​females when males chase them and flee. Mothers often whistle their offspring for several days after birth.

Bottlenose dolphins distinguish different frequencies depending on what they want to communicate. Low-frequency sounds (0.25-50 kilohertz) are used to communicate in social situations while high frequencies serve in echolocation. Another case: during the aggressive persecutions of Indo-Pacific dolphins (Tursiops aduncus), they issue a kind of crunch that is called “pop” sound.

The human ear perceives successive clicks as a sound without interruption, but the truth is that they are short. We do not know much about the purpose of the different sound emissions and researchers are still working on sound-target identification.

SIGNALS WITHOUT “VOICE.”

Although dolphins rely primarily on sounds to exchange information, they also communicate through touch and body language:

Identification of body coloring patterns.
Stains, stripes, and specks may indicate to other dolphins the health status or the age of their companions. For example, the skin of the Atlantic spotted dolphin (Stenella frontalis) develops spots when it begins to get old, and the scars in the skin of the Risso dolphin (Grampus griseus) informs others of their combat skills and experience.

Postures.
The body positions convey the idea of ​​the dolphin’s mood. An S-shaped posture demonstrates anger or aggression and is a way of saying “do not mess with me now.” If they are in a fight, they can expand their pectoral fins and extend their jaws to look bigger and more dangerous.

Touch.
The skin of these cetaceans is very sensitive to the touch. If they are in a good mood, then they can make physical contact with the flippers by pressing them against the flippers of another dolphin.

Tail Slapping.
It is a vertical blow of the tail against the water surface that often indicates aggressiveness, but it can also express the desire to leave the area where they are or ask for attention.

Flipper Slapping.
It probably has the same goals as the blows on the surface with the tail, but in this case, Dolphins hit their flippers against their body or the water surface.

DOLPHIN LANGUAGE AND COMMUNICATION

Dolphins are almost constantly making one of two kinds of sounds: communicative or navigational. They produce these different sounds in a variety of ways.

Echolocation sounds are produced in their nasal passages just below their blowholes and are called clicks. Dolphins create these clicks sometimes in such rapid succession that they sound like buzzes or even quacks. These sounds are produced just behind the melon, an oily, slightly off-center lump on what you’d call the dolphin’s forehead, and the sound waves are focused forward through this organ.

Scientists are not entirely certain how the melon works, but it does seem to amplify, clarify and direct the dolphin’s echolocation sounds which allow dolphins to detect remarkably detailed information from the world around them. In one test, a dolphin found a marble-sized sphere at more than the length of a football field. Some scientists speculate that echolocation sounds may also be used to deliver an acoustic shock to small prey.

In the larynx, dolphins can produce high-pitched whistles and squeals which can rapidly change pitch. Whistles are single tones, with no vibrations that make them sound like buzzes. As far as scientists can tell, the whistles are a form of communication with other dolphins, and squeals are used to express alarm or sexual excitement.

DOLPHIN COMMUNICATION

Like some other animals, dolphins do have communication. But do they communicate linguistically? There’s some evidence for it. Dolphins tend to stay within their pods and may have trouble understanding “foreign” dolphins. In studies done on dolphins near Scotland, individuals appear to have names; or at least, other dolphins use specific and unique whistles only in the presence of certain other dolphins, as if calling them by name. Unlike any other animal besides humans, dolphins exhibit a tendency to take turns when vocalizing – making their communications sound like a conversation.

There have also been very basic linguistic studies of dolphin sound patterns. According to some studies, dolphin sounds follow the same basic patterns of all human-based language, from Morse code to Chinese.

References

https://dolphins.org/communication

Denise L. Herzing. Dolphin Communication and Cognition: Past, Present, and Future. MIT Press, 2015.

Thomas I. White. In Defense of Dolphins: The New Moral Frontier. John Wiley & Sons, 2007.

Roitblat, Herman, Nachtigall. Language and Communication: Comparative Perspectives. Psychology Press, 2013.

http://www.bbc.com/news/science-environment-23410137

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

There is a lot of information that anyone interested in these animals should appreciate. There are plenty of great facts about them that you will learn when you get done reading this! Some are basic, others entertaining and many are simply amazing.1. Dolphins are odontocete cetaceans. The order Cetacea includes a group of mammals fully adapted to life in the ocean, and the suborder Odontoceti includes those with teeth.

2. The closest relatives of dolphins are whales and porpoises. All are members of the order Cetacea.

3. Dolphins are mammals; warm-blooded animals which give birth to live offspring and feed them with breast milk from the mother.

4. They do not have hair on the skin. Only a small accumulation of thin hair near the spiracle and in some other places. Only the Boto, Amazon River Dolphin, has a small amount of hair that they keep as an adult.

5. Dolphins are the only mammals that give birth to its offspring delivering the tail first instead of the head.

6. Like whales, manatees, seals, walruses and porpoises, they are mammals that live permanently in an aquatic environment.

7. Apparently, dolphins sleep resting one side of the brain at a time.
Thanks to its bone structure and its ability to hold air in the lungs for a long time, dolphins can rest underwater. However, they need to breathe regularly. Therefore, some degree of awareness is necessary, and one side of the brain remain active, while the other part rests.

8. Dolphins can communicate with each other by emitting a variety of sounds.

9. Dolphins do not have a good sense of smell.

10. Dolphins can swim at a speed of up to 25 miles per hour for a long time; This is about three times faster than the fastest humans in the world.

11. Dolphins inhabit all seas of the world.

12. Most species live in salt water, but some dwell in fresh or brackish waters.

13. All dolphins are carnivores.

14. There are about 100 teeth in the mouth of a dolphin, but the amount varies among species. However, they use the teeth to grab their prey, but they don’t chew it. All food is swallowed whole.

15. Dolphins can hear a frequency range ten times broader than that of a human being.

16. Dolphins are mostly larger than porpoises. However, some species of dolphins are the smallest cetaceans.

17. Mothers breastfeed calves for 2 or 3 years.

18. The lower limbs of dolphins are vestigial legs because millions of years ago they could walk on land.

19. There are about 43 species of dolphins. But the number keeps changing because of new discoveries and new taxonomic classifications.

20. There have been cases of attacks on humans, but they are very rare. Even though dolphins are usually very mild tempered, they can be aggressive.

21. At birth, calves weigh approximately 10 kilos and measure around one meter. This weight increases up to 7 times during the first year of life.

22. Many individuals have been seen making jumps in front of the ships and following the bow waves.

23. The teeth of dolphins work as a kind of antenna to pick up the sounds bounced back during echolocation.

24. Dolphins enjoy socializing and playing. They have been seen playing with small objects and with other dolphins. They play with seaweed or with other members of the pod. Sometimes, they will tease other living creatures in the water.

25. They are social animals and can live in groups called pods that can have hundreds of members or even join with other groups creating superpods with thousands of individuals.

26. The favorite foods of many species of dolphins are fish, octopus, and squid.

27. The gestation period in most species lasts between 10 and 12 months.

28. The Killer Whale (Orcinus orca) is the largest dolphin. It can measure up to 30 feet in length.

29. Dolphins detect prey and objects using their echolocation, that is, by interpreting the echo of sound waves bounced back by the target.

30. They have very delicate skin, which can easily be injured.

31. Dolphins have an organ called melon in the head that emits the sound waves used for echolocation.

32. The dolphin’s brain is similar in size to that of humans.
Their brains are 4-5 times larger than those of other animals of similar size.

33. Dolphins can recognize themselves in the mirrors which mean that they are self-aware, an indicator of intelligence.

34. Dolphins’ eyes can move separately from each other.

35. Bycatch is one of the main threats to the survival of dolphins.

36. Their main natural predators are sharks and ironically, orcas.

37. The Amazon River Dolphin or Boto is the largest dolphin that dwells in freshwater. They can be up to 10 feet long.

38. The Amazon river dolphins (Inia geoffrensis) can swim backward. So far, researchers unknown the exact reason for this behavior, but it is presumed to be related to searching food.

39. Dolphins have two stomachs just like cows. The first one stores the food and the second is where digestion takes place.

40. Some dolphin species can submerge up to 1,000 feet.

41. The dorsal fin on each dolphin is unique, and it can be used to identify them from each other.

42. The average lifespan of dolphins is around 17 years. However, some species in the wild live about 50 years.

43. Some dolphins need to breathe every 20 seconds, but others need to do it every 30 minutes.

44. The bonds between the members of a pod are very tight. They have been observed helping sick, elderly, and injured peers.

45. Dolphins can see well in the water due to the way their retina collects the light.

46. The brain of dolphins is the second largest ratio between size compared to its body size; only behind humans.

47. It is possible for a mature dolphin to eat up to 30 pounds of fish per day.

48. Some dolphins can leap up to twenty feet in the air.

49. Dolphins often use a hunting technique consisting in surrounding a school of fish, so they make a tight group. Then they will take turns going through the center of the accumulation to feed.

50. Global warming continues to be a problem for dolphins as it has reduced their food supply significantly.

51. Dolphins can migrate looking for food and reach parts of the ocean where the temperatures are right for them. Not all species of dolphins migrate.

52. Dolphins perform several feeding strategies to capture prey. Most involve cooperation among the pod members.

53. The smallest dolphins are about 4 feet long with the longest being 30 feet long. They can weigh from 90 pounds to more than 11 tons.

54. The flukes are the two parts of the tail of a dolphin.

55. All dolphins have a blowhole at the top where they breathe.

56. Dolphins have a great healing process even when they have deep wounds such as those that are the result of shark bites. Experts haven’t been able to determine how this is possible for dolphins when other mammals would die from a hemorrhage.

57. Dolphins are incredibly intelligent creatures, known for their ability to recognize themselves in mirrors and communicate with each other using distinct whistles. Learn more about this fascinating fact of the day.

Oceanic dolphins are aquatic mammals, members of the family Delphinidae which is part of the infraorder Cetacea.

They are closely related to whales and porpoises which are also cetaceans.

A group of dolphins is called a pod.

A pod usually is formed of around 12 dolphins, and it is the usual social group of dolphins.

However, when a group of pods joins in places with an abundance of food, they can reach up to one thousand individuals forming a large group which is called a superpod.

Superpods are not for a long time, and they dissolve after a while.

Additionally, another way to call a group of dolphins is “school.”

A dolphin pod is a group of dolphins.

Dolphins are social creatures and they group in pods (also called schools) of up to a dozen individuals for mating, hunting and protecting each other.

Sometimes pods join temporarily in places with an abundance of food forming a superpod, but it is not for a long time.

According to some sources, there are 43 species of dolphins, 38 species of dolphins which belong to the family Delphinidae of oceanic dolphins and five species of river dolphins. However, during 2011 a new species, the Burrunan dolphin was discovered, increasing the number to 44.

Dolphin Species List

1. Long-Beaked Common Dolphin, Delphinus capensis
2. Short-Beaked Common Dolphin, Delphinus delphis
3. Bottlenose Dolphin, Tursiops truncatus
4. Indo-Pacific Bottlenose Dolphin, Tursiops aduncus
5. Northern Rightwhale Dolphin, Lissodelphis borealis
6. Southern Rightwhale Dolphin, Lissodelphis peronii
7. Tucuxi, Sotalia fluviatilis
8. Costero, Sotalia guianensi
9. Indo-Pacific Hump-backed Dolphin, Sousa chinensis
10. Indian humpback dolphin, Sousa plumbea
11. Atlantic Humpbacked Dolphin, Sousa teuszii
12. Atlantic Spotted Dolphin, Stenella frontalis
13. Clymene Dolphin, Stenella clymene
14. Pantropical Spotted Dolphin, Stenella attenuata
15. Spinner Dolphin, Stenella longirostris
16. Striped Dolphin, Stenella coeruleoalba
17. Rough-Toothed Dolphin, Steno bredanensis
18. Chilean Dolphin, Cephalorhynchus eutropia
19. Commerson’s Dolphin, Cephalorhynchus commersonii
20. Heaviside’s Dolphin, Cephalorhynchus heavisidii
21. Hector’s Dolphin, Cephalorhynchus hectori
22. Risso’s Dolphin, Grampus griseus
23. Fraser’s Dolphin, Lagenodelphis hosei
24. Atlantic White-Sided Dolphin, Lagenorhynchus acutus
25. Dusky Dolphin, Lagenorhynchus obscurus
26. Hourglass Dolphin, Lagenorhynchus cruciger
27. Pacific White-Sided Dolphin, Lagenorhynchus obliquidens
28. Peale’s Dolphin, Lagenorhynchus australis
29. White-Beaked Dolphin, Lagenorhynchus albirostris
30. Australian Snubfin Dolphin, Orcaella heinsohni
31. Irrawaddy Dolphin, Orcaella brevirostris
32. Melon-headed Whale, Peponocephala electra
33. Killer Whale (Orca), Orcinus orca
34. Pygmy Killer Whale, Feresa attenuata
35. False Killer Whale, Pseudorca crassidens
36. Long-finned Pilot Whale, Globicephala melas
37. Short-finned Pilot Whale, Globicephala macrorhynchus
38. Guiana dolphin, Sotalia guianensis

River Dolphins

1. Boto (Amazon River Dolphin), Inia geoffrensis
2. Chinese River Dolphin (Baiji), Lipotes vexillifer (considered functionally extinct)
3. Ganges River Dolphin, Platanista gangetica gangetica
4. La Plata Dolphin (Franciscana), Pontoporia blainvillei
5. Indus River Dolphin, Platanista gangetica minor

New Species

Burrunan Dolphin, Tursiops australis

Dolphins communicate through a group of several specialized sounds and whistles. There are several kinds of them used by these cetaceans.

Some species of dolphins can send identity information through signature whistles.

Whistles also coordinate group hunting which makes feeding much easier and efficient for dolphins than doing it alone.

Burst-pulsed sounds are also made by dolphins with the purpose of communication, although there is not enough knowledge about dolphin communication.

After mating, female bottlenose dolphins start the gestation period which lasts approximately twelve months.

After this time, a single calf is born, usually with the help of another female dolphin which assumes the role of a midwife.

Dolphin mothers give birth to the calf by releasing the tail of the offspring first, to avoid that the new dolphin gets drown.

The mother nourishes the calf for up to 18 months with milk produced by her body.

After weaning, young dolphins stay with their mothers for around six years until they have developed all the skills for hunting and surviving.

Dolphin calves are born after long gestation periods inside their mothers that range between 11 and 17 months according to the species.

Mothers deliver calves with the aid of another female dolphin who makes the role of a midwife.

Calves stay with their mothers for several years until they can survive by themselves.

After approximately six years, a time which also varies according to the species, young dolphins can hunt and protect themselves, so they leave their mothers and start an independent life.

This independent life sometimes means moving to another pod, but this is not a rule in all species as in some cases, just the females move to another group.