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Posts Tagged ‘native’

Two more pups have joined the Hawaiian monk seal population.

On June 26, RK28 gave birth to a healthy pup, her first pup born on Kauai in four years. Here is PK3 on the day of his/her birth.

rk28 and pup day oneAs you may recall, in 2014, RK28’s two-week old pup was tragically killed during a night-time dog(s) attack that also left dozens of puncture wounds on four other seals, including RK28 who likely valiantly tried her best to protect her pup. It was a tragedy, especially since it’s one that could have been prevented simply by not letting dogs run free. Please share this story when chatting with folks on the beach about the various threats these endangered monk seals face. To read more about this tragedy, click here.

Two years ago, in 2016, RK28 was observed with large mobbing wounds and abscesses on her back, the scars of which are still visible on her back. These wounds are caused by male monk seals and have been observed in other females. The Hawaiian Monk Seal Research Program reports this kind of male behavior can involve multiple males competing to mate with an adult female or a single male targeting a younger seal. To read more about adult male aggression, click here.

But back to some good news. Just two days ago, on June 30, RO28 provided the species with another member. This is RO28’s sixth pup in as many years on Kauai. Here is PK4 on the day of his/her birth. RO28 and pup day one

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Last fall, the Hawaiian Monk Seal Research Program placed dive recording tags on two monk seals that make their home in Kauai waters. We briefly wrote about it here. During one recording period, the two seals (R1KT and R7AA) both made numerous dives deeper than 150 meters (492 feet). One bottomed out at 170 meters (557 feet) and the other at close to 200 meters (656 feet).

These are mammals diving to 500 feet on a single breath of air. But that’s not unusual for monk seals. In fact, the deepest known dive for a monk seal occurred in 2003 when scientists in a Pisces submersible descended to a depth of 543 meters (1,781 feet). They were studying deep sea corals, submarine canyons, and seamounts when a Hawaiian monk seal swam into their field of view. The on-board microphone captured their reaction. It went like this:

“Whoa.”

“What’s that?”

“That’s a monk seal.”

“Oh my god.”

“No way.”

“Look it. Right in front of us.”

“No way.”

“Oh my god.”

So, how do they do it? How do monk seals dive to depths of 1,781 feet?

There are numerous physiological responses involved; collectively the process that allows monk seals to dive deep is known as “mammalian diving reflex.” It involves the respiratory and cardiovascular systems. Typically, before a dive, seals exhale completely. This allows their lungs to completely collapse and avoid gas transfer at depth that could cause nitrogen narcosis. Then, holding their breath, the heartbeat slows from about 125 beats per minute to as low as 10 beats per minute. This is known as bradycardia. A slowing heart rate reduces oxygen consumption. Too, blood is diverted from the limbs and all organs except the heart and brain. This is known as blood shift. It’s accomplished through a process known as peripheral vasoconstriction. Too, diving mammals have high blood volume. That is, elevated hemoglobin and myoglobin levels, which provides greater oxygen storage. The whole idea is to conserve oxygen consumption, so the seal can dive deeper and longer.

Simply, they can hold their breath, slow their heart rate, and direct blood to just the heart and brain. This also helps explain their torpedo-like shape and abbreviated pectoral fins.

Here’s a video of that astonishing 1,781-foot-diving monk seal.

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