Dolphins

Can hunting by echolocation be as fast as hunting by sight?

As visual animals, we may find this a peculiar question—not so if one applies it to animals that hunt using echolocation, like bats, dolphins and whales. These animals emit clicking sounds and use the reflected echoes to determine the location of objects and other animals.

Can animals that hunt using echolocation lock onto their prey and track their movements, and how fast can they react? These were questions that an international team of researchers sought to answer.

In 2019, a pair of bottlenose dolphins in the Caribbean—a mother and her calf—was filmed in the Chetumal-Corozal Bay in northern Belize using mud rings to catch fish.

This method of catching fish was first observed and documented in several parts of Florida by Stefanie Gazda, a researcher from University of Florida in 2005.

Equipped with an autonomous hydrophone, the buoy's function is to conduct for the first time real-time acoustic monitoring of the water's cetaceans to assess how oceanic noise pollution affects them. 

Deployed as part of the Smart Whale Sounds project, it will also track the distribution and behaviour of whale species in real-time and be used to train machine learning models to identify different species' calls. 

Marine mammals are not above the physical principles and processes that lead to bubble formation in tissues following decompression. Scientists once thought that diving marine mammals were immune from decompression sickness, but beached whales have been found to have gas bubbles in their tissues—a sign of the bends. In any case, how some marine mammals and turtles can repeatedly dive as deep and as long as they do has perplexed scientists for a very long time.

This scenario may one day become reality. And to be efficient, such robots would need to be maneuverable and stealthy, and be able to closely mimic the movements of the marine creatures.

Scientists like Keith W. Moored are working on the next generation of underwater robots by studying the movements of dolphins and whales. "We're studying how these animals are designed and what's beneficial about that design in terms of their swimming performance, or the fluid mechanics of how they swim."

The Wildlife Trusts, which comprises 46 individual wildlife trusts around the country, reports record numbers of more than 800 sightings of whales, dolphins and seals in the waters of the United Kingdom in 2019.

Its Yorkshire project reported hundreds of individual sightings by trained citizen scientists. Among these were a pod of bottlenose dolphins making their way from Scotland to Flamborough Head in East Yorkshire-the farthest south they had been officially identified.

Whether or not you have watched (or agree with) the movies Free Willy or Blackfish, the predicament of captive cetaceans is one that can spark off a heated debate from both sides of the fence.

Nonetheless, such movies and increased awareness have led to public calls for attractions and venues that keep wild animals captive to release them.

Marine-animal attractions like SeaWorld are particularly under fire due to their animal shows featuring captive cetaceans trained to perform for public entertainment.

When air-breathing mammals dive, their lungs compress. The ultra-deep-diving feats of some marine mammals go beyond our current understanding of respiratory physiology and lung mechanics. But historically, researchers assumed the chest structure of marine mammals meant their lungs compressed automatically at great depths, an adaptation that prevented them from taking up excess nitrogen and getting the bends.

Instead of wearing earplugs at a rock concert, imagine you could simply tune a dial inside your ears to lower the volume and protect your hearing. In a new report published in Integrative Zoology, researchers have discovered four whale species and dolphins can do just that. This could potentially shield the animals from navy sonar and oil drilling, linked to at least 500 marine mammal deaths since 1963.

The Mexican government has now permanently banned gillnets and night fishing in the upper Gulf of California, which is the only place in the world where the critically endangered porpoise is found.