Dolphins

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.

A study by researchers from University of Milano-Bicocca describes observations of adults carrying dead calves and juveniles in 7 toothed cetaceans (odontocetes). The observation was based on 14 events from 3 oceans. The seven species studied were Indo-Pacific bottlenose dolphins, killer whales, Australian humpback dolphins, sperm whales, Risso’s dolphins, short-finned pilot whales, and spinner dolphins.

An international scientific expedition in Mexico's Gulf of California has spotted up to 25 critically endangered vaquita marina, the world's smallest porpoise. The sightings occurred during the first 20 days of the Vaquita Expedition 2015, which commenced on September 26th. However, scientists caution that some individuals may have been counted more than once.

According to a new study, bottlenose dolphin colonized the Mediterranean after the last Ice Age, about 18,000 years ago. Leading marine biologists collaborated in the study, the most detailed ever conducted into the genetic structure of the Mediterranean’s bottlenose dolphin population to date.

A study of bottlenose dolphin deaths in the Gulf of Mexico conducted between 2010 and early 2013 has concluded the highest number of strandings and deaths occurred in areas most impacted by the 2010 BP Deepwater Horizon oil spill. In comparison, Gulf Coast areas of Texas and Florida, which experienced little to no oiling, saw few statewide increases in stranded dolphins during the same period.

There was something peculiar about dolphins that puzzled the prolific British zoologist Sir James Gray in 1936. He had observed the sea mammals swimming at a swift rate of more than 20 miles per hour, but his studies proposed that dolphins simply do not have the strength to swim so fast. The conundrum came to be known as “Gray’s Paradox.”

Richard Connor of the University of Massachusetts Dartmouth tracked 120 males in the Shark Bay, Western Australia and found no evidence that dolphins form the groups to control either territory or sexual partners, suggesting their society is unusually open.

The researchers found no evidence that the large and complex social network in Shark Bay, comprising hundreds of bottlenose dolphins, is a closed group defended by males.

They also found no evidence that males defend smaller ranges or groups of females within this network.