Tag Archives: Dolphins

Captive Orcas Learn To Speak Dolphin

Although many species communicate acoustically, the vast majority of animals use a genetically innate repertoire of sounds to exchange information. But some species, including humans, are capable of imitating sounds and adding it to their own repertoire, a process known as vocal learning. It is thought that the acquisition of this ability may have been a first step in the evolution of human language.

Although this trait is extremely rare, it is not unique to humans and has been discovered in 6 groups of animals: 3 groups of birds and 3 groups of mammals. Now, thanks to new research, we know that killer whales are capable of cross-species vocal learning. When socialized with bottlenose dolphins in captivity, the team discovered that they transitioned from their typical vocalizations and emitted more dolphin-like noises. According to the researchers, this suggests that cetaceans (dolphins, whales and porpoises) may use this trait to facilitate social interactions. The work has been published in The Journal of the Acoustical Society of America.

Killer whales, or orcas, emit three main types of vocalization: clicks, pulsed calls and whistles, with pulsed calls being the dominant form of communication. These are known to vary across social groups in terms of duration and pitch, but killer whales living together tend to produce similar calls that are distinct to that particular group, which is known as a dialect. Researchers had their suspicions that killer whales learn this dialect, but there was no experimental proof. Since dolphins produce similar vocalizations to orcas, and the two are sometimes housed together in captivity, the researchers took this unique opportunity to investigate whether killer whales could learn vocalizations from their cross-species social partners.

For the study, the researchers analyzed recordings of vocalizations produced by 10 captive orcas; three of these lived with bottlenose dolphins for several years, whereas the rest were housed with their own species. They then compared these recordings with the vocalizations produced by the dolphins.

They found that 95% of the 1551 vocalizations made by the seven orcas that were living with members of their own species were the typical pulsed calls that dominate their repertoire. The orcas that were living with dolphins, however, emitted far more whistles and clicks, just like their cross-species social partners. Intriguingly, they found that one of the killer whales even learned how to produce an artificial chirp sequence that a human trainer had taught the dolphins before they were introduced to each other.

According to the researchers, this demonstration of cross-species vocal learning suggests that orcas have substantial vocal plasticity and are highly motivated to match the vocalizations of their social associates. This is important because the fate of orcas in groups disrupted by change, such as oil spills, will be partly dependent on their ability to socialize with new populations and thus their vocal plasticity.

[Via Acoustical Society of America, The Journal of the Acoustical Society of America and Science]

Read more: http://www.iflscience.com/plants-and-animals/captive-orcas-learn-communicate-their-dolphin-mates

River Dolphin Sonar Is Well-Suited For Life In The Busy Amazon

The echolocation clicks of toothy whales and dolphins typically encounter few obstacles at sea. Amazon river dolphins, on the other hand, live in shallow channels and flooded forests alongside dense vegetation confined environments where sonar operations might result in high levels of clutter and reverberation. According to new findings published in the Journal of Experimental Biology, these dolphins rely on a high-frequency, short-range biosonar.

Previous studies found that body size plays an important role in the evolution of toothed whale echolocation. Aarhus Universitys Michael Ladegaard and colleagues wanted to see if habitat shaped the evolution of their biosonar as well. They recorded the echolocation clicks of wild Amazon river dolphins (Inia geoffrensis, also called botos) in three locations in the Amazon during October of 2013: near So Tom in Brazil, at the confluence of Rio Negro and Rio Solimes, and in the Mamirau Sustainable Development Reserve. The dolphins were recorded from small aluminum-hulled boats, and an array of seven hydrophones were deployed vertically as the team drove slowly ahead of the animals. The researchers recorded almost 35,000 echolocation clicks, of which 268 were recorded head-on and within 21 meters (70feet) of the equipment.

These river dolphins, the researchers discovered, produce soft, high-pitched echolocation clicks that lasted 14.1 microseconds with a brief interval of 35 microseconds between the clicks.

By increasing the frequency of their clicks, these freshwater dolphins could direct their sonar better than their ocean faring cousins. With soft, lower amplitude clicks, echoes only return from nearby objects. That means all of the echoes that they need to interpret return within milliseconds, Inside JEB explains, allowing them to produce high rates of about 30 clicks a second, while limiting reverberations.

Low-amplitude, highly directional biosonar systems, the team argues, are advantageous in riverine habitats because they simplify the auditory scene and help with target detection in cluttered, acoustically complex spaces.

Read more: http://www.iflscience.com/plants-and-animals/amazon-river-dolphin-biosonar-well-suited-cluttered-environments

New Species of Humpback Dolphin Discovered

A new species of humpback dolphin has been discovered off the northern coast of Australia,. Though it has not been named yet, genetic testing and comparison of physical features have distinguished the species from other humpback dolphins. 

 

Humpbacks have a characteristic bend in their back below the dorsal fin. They are found in Atlantic and Indo-Pacific waters. The humpback dolphins found in the Atlantic are all one species, but this discovery would put a third species in the Indo-Pacific region. 

 

The findings were published in Molecular Ecology and represent a collaboration between several organizations, including American Museum of Natural History and the Wildlife Conservation Society. More than 180 skulls and 235 tissue samples were analyzed for genetic and morphological differences before coming to the conclusion that the researchers were dealing with a brand new species.

 

The discovery is not only interesting because it adds to the number of animal species on Earth, but understanding differences between dolphin populations will help scientists and conservation workers join forces to protect them as best as they can. As they learn more, their findings could help influence new conservation policies.

 

Humpback dolphins can grow to be 8 feet (2.4 meters) long, with coloration that ranges from pink to dark grey. Habitat loss and fishing are threatening humpback dolphins. The Atlantic dolphin is listed as “Vulnerable” by the IUCN’s Red LIst, while the two previously-discovered Indo-Pacific dolphins are “Near Threatened.”

Read more: http://www.iflscience.com/plants-and-animals/new-species-humpback-dolphin-discovered

Toxic Levels Of Chemicals Found In European Marine Mammals

It is looking more and more likely that orcas swimming in European waters will soon be a thing of the past. An extensive study investigatingfour species of whales and dolphins living off the coast of Europe has found that the levels of a harmful chemical, polychlorinated biphenyl, inthe marine mammals’ fat are the highest recorded anywhere in the world. They have also concludedthat the highconcentrations of this chemical in the animalsis likelythe cause of supressed reproduction rates seen among the orca and other species around Europe since the 1960s.

Before they were banned, polychlorinated biphenyl compounds or PCBs were commonly used in electronics, paints, and as fire retardants, until it was discovered that they were highly toxic, and subsequently banned. PCBs are known to bioaccumulate, meaning that they build up in the food chain,often becoming concentrated in the animals that take the top spots, such as whales and dolphins. As with many harmful chemicals, they have managed to persist in the environment, and are still having a major impact on these marine mammals found in the north eastern Atlantic and Mediterranean.

Orca are espcially vulnerable to PCBs as they are at the top of the food chain. This is one of the last eight surviving orca living off the north West coast of the U.K.Kerry Froud_Hebridean Whale and Dolphin Trust

In the striped dolphins, bottle nosed dolphins, and killer whales, we have mean PCB levels that are excessive, explained Dr. Paul Jepson, lead author of the study published in Scientific Reports. They are probably the highest in the world right now, by some way. Europe is a big hotspot for PCBs, in particular the western Mediterranean Sea and around the Iberian Peninsula.

After their use was banned in the 1980s, the levels of PCBs found in whale blubberdid drop until around 2000, when the concentrations found in the marine mammals plateaued. So its quite likely now that were in a steady state condition where whatever PCB is metabolised or excreted is topped up by new inputs, says Dr. Jepson.

The study also looked at striped dolphins (pictured), bottle nosed dolphins, and harbor porpoises. Andrea Izzotti/Shutterstock

And these inputs are expansive. After the chemical was banned in the 1980s, only around 10 percent of it was destroyed. Due to its high resistance to heat, one of the exact reasons it was so popular in manufacturing, its incredibly difficult to get rid of. This meant that the vast majority of the PCB produced was simply buried in landfill. It is from these sources thatthe chemical is slowly seepinginto the oceans, as well as the dredging of sedimentsstirring up the PCB from the sea floor, topping up the concentration of the PCBin the food chain, and eventually reaching whales and dolphins.

This has resulted in the decline in populations, particularly of bottle nosed dolphins and orca, as the chemicals impact the mammals’ ability to reproduce, while also supressing their immune system. In fact, there are now no pods of orca that live year round in the North Sea, and only eight individuals living off the north west coast of the U.K. Despite having been studied for a long time, this last remaining population of orca has never bred, and is unlikely to in the future.

Photo Gallery

Read more: http://www.iflscience.com/plants-and-animals/toxic-levels-chemicals-found-european-marine-mammals

Two-Headed Dolphin Washes Up On Turkish Beach

It’s not unusual for dead marine organisms to wash up along shores, but a particularly bizarre specimen has graced us with its presence recently- a two-headed dolphin calf.

According to Dogan news, the dead dolphin, which was discovered by a gym teacher on vacation, washed up onto a beach in Dikili, Turkey, from the Aegean Sea last week. It is reported that marine biologists at Akdeniz University will examine the carcass to find out more.

According to the Daily Mail, the calf was believed to be around one-year-old and measured 3.2 ft (1 meter) in length. Early reports stated that the eyes were not fully opened on one of the heads and neither was one of the blow holes.

The dolphin had a rare condition known as polycephaly. This two-headedness is a severe example of conjoined twins which results from the incomplete splitting of a fertilized egg. The result is a shared body with separate heads. Polycephaly has been observed in numerous animals such as snakes, sheep, dogs, fish and people. 

[Via Houston Chronicle and Daily Mail]

Read more: http://www.iflscience.com/plants-and-animals/two-headed-dolphin-washes-turkish-beach

Dolphins and Belugas Squeal With Delight

Researchers pouring over 52 years of observations have discovered that dolphins and beluga whales actually squeal with delight when they’re rewarded with tasty fish treats. Insert squee!! (rather, eeeeeeee!!) here. The findings were published in the Journal of Experimental Biology this week. 

Sam Ridgway of the U.S. Navy’s Marine Mammal Foundation has worked with cetaceans since the 1960s. Whether studying how deep they dive or how depth affects their hearing, he’s always trained the animals with food rewards. They’d squeal a high-pitched “eeeee” each time they received their treat; sometimes they’d emit the sound in sheer anticipation. Ridgway had thought that these were food signals, he tells Inside JEB, that the animals were communicating the presence of food to others in their population nearby. But maybe not… after all, the sound reminded him of a child’s happy squeal. 

To see if these were genuine expressions of delight, Ridgway and an all-San Diego team examined decades-worth of recordings from experiments where bottlenose dolphins (Tursiops truncates) and belugas (Delphinapterus leucas) were trained for various projects — paying particular attention to their “victory squeals.” 

Animal trainers often couple rewards with a sound, like a buzz or a whistle. When the task is mastered, the trainer stops giving out food and uses just the sound to let the animals know that they performed successfully and to expect a treat later. Even without a food reward, the cetaceans squealed in response to the sound. “The behavior had transferred over to another stimulus that wasn’t food,” Ridgway explains

Additionally, the researchers also trained two belugas rescued from Canada and four dolphins from the Pacific and the Gulf of Mexico to dive below and turn off an underwater buzzer by pushing a button. They made victory squeals right afterwards. 

Ridgway suspects it has something to do with the pleasure chemical dopamine. Back in the 1950s, researchers showed how animals appeared to derive delight from electrical stimulation of the brain region that releases dopamine — as much so as they did with a food reward. In lab animals, a dopamine release takes 100 to 200 milliseconds. So, the team measured the delay between the trainer’s signal and the observed victory squeals. If the delay between the promise of reward and the squeal was longer than the dopamine release period, that would likely mean that the animal was expressing pleasure.

They found that dolphins take an average of 151 milliseconds of extra time for this release, and the belugas showed a 250 millisecond delay. Though the researchers didn’t directly measure the neurotransmitter in the brain, Science explains, that’s enough time for dopamine to spark the sound. 

Looks like victory squeals may have an emotional content after all. You can listen to a dolphin’s victory squeal after it closes in on a fish in this video

[Via The Company of Biologists]

Read more: http://www.iflscience.com/plants-and-animals/dolphins-and-belugas-squeal-delight

Boaters Witness Giant Dolphin Stampede While Whale Watching

Captain Dave’s Dolphin and Whale Safari takes passengers for a nature watching boat ride off the coast of Dana Point, California. But even Captain Dave admits it isn’t everyday he catches an enormous Dolphin Stampede in action. 

So it was great luck that one boat full of passengers were in the right place at the right time to witness a pod of nearly 1,000 dolphins charging some nearby whales. 

 

Read more: http://www.viralviralvideos.com/2013/01/09/dolphin-stampede-while-whale-watching/