Bottlenose dolphins have a 'super sense' previously unknown to science

Recent research by Tim Hüttner and Guido Dehnhardt from the University of Rostock, Germany, has revealed a remarkable discovery about bottlenose dolphins. Known for their intelligence and agility, these marine mammals are now suspected to have an additional sensory ability – the detection of weak electric fields. This finding could revolutionize our understanding of dolphin behavior and sensory capabilities.

Studying bottlenose dolphins

The study began with an observation of bottlenose dolphin calves, which are born with two rows of whiskers on their beaks that eventually fall out, leaving behind vibrissal pits.

Hüttner and Dehnhardt noted that these pits closely resemble the structures in sharks that enable them to detect electric fields. Intrigued by this similarity, they decided to investigate further.

In collaboration with Lorenzo von Fersen at Nuremberg Zoo and Lars Miersch at the University of Rostock, Dehnhardt and Hüttner designed experiments to test the dolphins’ sensitivity to electric fields.

The team first examined how sensitive two bottlenose dolphins, Donna and Dolly, were to varying electric fields to determine their ability to detect a fish buried in the sandy sea floor. Hüttner, Armin Fritz from Nuremberg Zoo, and a team of colleagues trained the dolphins to rest their jaws on a submerged metal bar.

They then taught them to swim away within 5 seconds upon detecting an electric field from electrodes placed just above their snouts. As the researchers progressively reduced the electric field strength from 500 to 2μV/cm, they meticulously recorded the frequency of the dolphins’ correctly timed departures.

What the research team learned

The experiments yielded fascinating results. Donna demonstrated slightly higher sensitivity than Dolly as the electric fields weakened, detecting fields as low as 2.4μV/cm compared to Dolly’s threshold of 5.5μV/cm.

The team recognized that living animals produce fluctuating electric fields, not just static ones, due to the pulsing movements of fish gills. To test this, they varied the electric field pulses at 1, 5, and 25 times per second while lowering the field strength.

Both Donna and Dolly detected these pulsing fields. However, their sensitivity to these alternating fields was not as high as it was to steady fields. Dolly detected only the slowest pulsed field at 28.9μV/cm, while Donna sensed all three, with the slowest at 11.7μV/cm.

Implications of this “super sense”

Dehnhardt explains the practical significance of this finding, stating that the ability to detect weak electric fields aids dolphins in locating fish hidden in sediment. This skill differs from sharks, who can sense electric fields from a greater distance.

Hüttner and Dehnhardt propose that dolphins’ ability to perceive electricity might aid them on a larger scale. Dehnhardt explains, “Dolphins could use this sensory ability to orient themselves to the Earth’s magnetic field.”

He suggests that dolphins swimming at a normal speed of 10m/s through weak areas of the Earth’s magnetic field could produce a detectable electric field of 2.5μV/cm across their bodies. Moreover, swimming faster increases their likelihood of sensing the planet’s magnetic field, enabling them to navigate globally using an electric sense-based magnetic map.

In summary, this surprising discovery by Hüttner and Dehnhardt opens new avenues for understanding the sensory world of dolphins. It highlights their remarkable adaptability, and also poses exciting questions about the evolutionary purpose and ecological implications of this newfound electrosensitivity “super sense” in dolphins.

More about bottlenose dolphins

Bottlenose dolphins, scientific name Tursiops truncatus, captivate people worldwide with their intelligence, agility, and playful behavior. These marine mammals, known for their curved mouths giving the appearance of a friendly “smile,” belong to the family Delphinidae. They inhabit warm and temperate seas worldwide and have become one of the most studied and recognized dolphin species.

Physical characteristics of bottlenose dolphins

This dolphin species typically measures between 2 to 4 meters in length and weighs around 150 to 650 kilograms. Their sleek, streamlined bodies, adapted for swimming, display a grayish-blue color with a lighter underside. They possess a distinctive dorsal fin, which provides stability while swimming. These dolphins have a well-developed sense of hearing and eyesight, both above and below the water.

Diet and hunting techniques

Bottlenose dolphins are carnivorous, primarily feeding on a diet of fish and squid. They employ sophisticated hunting techniques, including the use of echolocation. By emitting sound waves that bounce off objects, they can locate and identify their prey with remarkable precision. In some regions, they have developed unique hunting strategies, like mud-ring feeding, where they trap fish in muddy circles before feasting on them.

Social behavior and communication

Bottlenose dolphins are highly social animals, living in groups called pods. These pods can contain anywhere from a few individuals to over a dozen. They communicate using a complex array of whistles, clicks, and body language. Each dolphin has a unique signature whistle, functioning like a name, allowing them to call out to specific individuals.

Intelligence and training

Renowned for their intelligence, bottlenose dolphins can learn and perform complex tasks, making them stars in many aquarium shows. They have the ability to understand symbolic language, use tools, and exhibit problem-solving skills. Researchers continually discover new aspects of their cognitive abilities, deepening our understanding of these fascinating creatures.

Reproduction and lifespan

Female bottlenose dolphins reach sexual maturity around 5-12 years of age, while males mature a bit later, around 10-12 years. They mate throughout the year, with a gestation period of about 12 months. A calf is born tail-first and quickly rises to the surface for its first breath. Calves typically stay with their mothers for 3-6 years. In the wild, bottlenose dolphins can live up to 40 years or more.

Conservation status

While bottlenose dolphins are not currently endangered, they face threats from habitat loss, pollution, and fishing nets. Various conservation efforts focus on protecting their natural habitats and reducing human-induced threats. Public awareness and responsible ecotourism play significant roles in the conservation of these magnificent creatures.

In summary, bottlenose dolphins, with their remarkable abilities and charismatic nature, continue to intrigue and delight humans. Their presence in the oceans reminds us of the complexity and beauty of marine life and the importance of preserving such incredible species for future generations.

Understanding and respecting these intelligent creatures is crucial for their continued survival in the ever-changing marine environment.

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