Sperm whales are one of the deepest diving whales on the planet and make dives of more than 2000ft below the ocean's surface lasting up to an hour while they search for the squid they feed on.
The calves, however, cannot make these dives and have to remain at the surface. This leaves the calves vulnerable to killer whales which often follow pods of sperm whales to prey upon.
Pygmy blue whales are the smallest members of the blue whale family, but that's the only small thing about them: they can reach up to 24 meters long.
Despite their enormous size, blue whales have been difficult to observe in the Southern Hemisphere as they live offshore and don't jump around like the humpback whales; thus, for some regions, their population structure, distribution and migration routes remain poorly understood. In particular, little is known about the blue whales in the northern Indian Ocean.
Narwhals, notwithstanding their unicorn-like tusks, are a mysterious species. They live in distant Arctic regions and hunt as deep as 1,000 meters down.
They orient themselves using echolocation, making clicking sounds to explore their surroundings. When they hunt, the clicking sounds turn into buzzing sounds as the interval times shorten.
A new population of pygmy blue whales has been discovered in the Indian Ocean, thanks to underwater nuclear bomb detectors that recorded their whale songs.
The research team, led by the University of New South Wales (UNSW), had been studying data from the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) which monitors international nuclear bomb testing, when an unusually strong signal caught their attention.
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.
Cetaceans were not limited by gravity in the buoyant marine environment and evolved multiple giant forms, exemplified today by the largest animal that has ever lived: the blue whale (Balaenoptera musculus).
There are tradeoffs, however, associated with large body size, including a higher lifetime risk of cancer due to a greater number of somatic cell divisions over time. The largest whales can have ∼1,000 times more cells than a human, with long lifespans, leaving them theoretically susceptible to cancer.
Using mercury and stable isotopes of carbon and nitrogen to obtain such information, the team were able to also analyse how the ice cover and the impact of potential toxic compounds have evolved over time.
Their findings were published in the Current Biology journal.
The tusks of the ten narwhals involved in the research were 150 to 248 cm long, and contained data from the time period 1962 to 2010.
Four of the six baleen whale species found in the western North Atlantic Ocean (humpback, sei, fin and blue) have changed their distribution patterns in the past decade.
Using 281 passive acoustic recorders moored to the sea floor from the Caribbean Sea to Greenland, researchers from the United States and Canada monitored the movements of the whales from 2004 to 2014. The findings of their study was published in the Global Change Biology journal.
Belugas are gregarious, highly sociable and they regularly form small groups, or pods, which may contain between two and 25 individuals, with an average of 10 members.
Rice's whale (Balaenoptera ricei), previously believed to be a population of Bryde’s whales, is an intermediate-sized species of baleen whale.
“I was surprised that there could be an unrecognized species of whale out there, especially in our backyard,”
—Lynsey Wilcox, geneticist with the US National Oceanic and Atmospheric Administration
We asked our contributors what their favorite marine mammal dive was and they sent us tales and images of magnificent whales, playful seals, endearing sea cows and curious dolphins.
