Seals & Sea lions

Elephant seal
Elephant seal. (Photo: Rhododendrites / CC BY-SA)

Elephant Seals as “Smart Sensors” of Fish Populations

This mysterious layer of water, between 200 and 1,000 meters below the surface, lies in  almost complete darkness, for the sun's rays can scarcely penetrate that far. Thus it is difficult or impossible to monitor using traditional tools. But while ships, buoys, and satellites can only capture a fraction of what’s happening below the waves, the seals’ foraging patterns can offer a far more expansive view of ocean life. 

Elephant seals employ specialised sensory adaptations to locate prey in the ocean's dark depths
Elephant seals employ specialised sensory adaptations to locate prey in the ocean's dark depths.

Hunting Tactics of Elephant Seals

Recent studies have revealed intriguing details about the hunting tactics of southern elephant seals, showcasing their remarkable adaptations for deep-sea hunting. These findings provide insight into the complex behaviours and sensory mechanisms that enable these massive predators to thrive in their challenging underwater environment.

One of the tagged Weddell seals in the study

Weddell Seals Time Their Hunts Strategically

New research from the Woods Hole Oceanographic Institution (WHOI) and partners reveals that Weddell seals that inhabit the icy waters of Erebus Bay, Antarctica, employ a careful hunting strategy when it comes to diving, timing their dives to balance energy use and foraging efficiency.

The study, published in Communications Biology, shows that the seals perform their longest and deepest dives early in the day, and not during midday when sunlight is at its peak. 

The hole in the ozone layer can cause eye damage in Antarctic animals.

Antarctic Wildlife Threatened by Lingering Hole in Ozone Layer

The ozone layer is back on our radar. Although its condition has improved after the Montreal Protocol was implemented, the hole reappears every spring over the Antarctic. 

In recent years, it is no longer just a winter phenomenon anymore; it Is stretching into the early summer, coinciding with crucial times in the life cycles of local wildlife and emerging vegetation, exposing them to the sun's ultraviolet rays. As our planet changes, the timing of this exposure could have profound effects on the delicate ecosystems of the Antarctic.

Male northern elephant seal
Male northern elephant seal

Elephant seals sleep and dive at the same time

A new study involving elephant seals fitted with caps similar to those worn by humans in sleep clinics to measure electroencephalographic activity, or brain waves, has revealed the seals take short naps during deep dives. Unlike other marine mammals, they enter rapid eye movement, or REM, sleep, with accompanying paralysis, but do so at depths below those occupied by their predators. 

The emergence of TB in Peru likely came from marine mammals such as seals and sea lions.
The emergence of TB in Peru likely came from marine mammals such as seals and sea lions.

Did marine mammals cause emergence of tuberculosis in the Americas?

DNA research has shown that Mycobacterium pinnipedii, which today causes tuberculosis (TB) primarily in pinnipeds, infected human populations living in the coastal areas of Peru prior to European colonisation

The earliest cases are found in Peru and northern Chile and are dated to ~700 CE, with possible cases occurring as early as 290 CE.

The researchers also discovered TB in the skeletons of people who lived nowhere near the coast some 400 to 1,000 years ago — a scenario incompatible with TB transmission directly from infected pinnipeds or their tissues.