"A Blue Whale's tongue is about the size and weight of a fully grown African Elephant"
(https://onekindplanet.org/animal/whale-blue/)
Despite being so massive, this giant of the ocean feeds on some of the smallest marine life – tiny shrimp like animals called krill. A single adult blue whale can consume 36,000 kg of krill a day.
Though we can’t hear them, blue whales are one of the loudest animals on the planet, communicating with each other using a series of low frequency pulses, groans, and moans. It is thought that in good conditions blue whales can hear each other across distances of up to 1,600km.
The whale’s mouth has a fascinating row of plates fringed with bristles to help it filter its main source of food – plankton from the water. There is what looks like a moustache of long bristles on the end of each plate to help it hold the minute prey. With each mouthful, the whale can hold up to 5,000 kg of water and plankton. Having forced the water out of its mouth, the whale licks these bristles with its fleshy tongue.
Although the blue whale is a deep-water hunter, as a mammal, it must come to the surface of the sea to breathe. When it surfaces, it exhales air out of a blowhole in a cloud of pressurized vapour that rises vertically above the water for up to 9m.
A baby blue whale (calf) emerges weighing up to 2,7000kg and up to 8m long. New born whales are helped to the surface of the water by their mothers and are often encouraged (nudged) by other females so that they can take their first breath of air.
Narwhal: (http://www.whalefacts.org/narwhal-facts/)
The name “Narwhal” comes from the old Norse word “nar”, which means “corpse like” when describing its grayish molted coloring which resembles the corpse of drowned sailors.
In addition to being called the narhwal these marine animals have also gone by the names of Monodon monoceros (one-toothed) and Qilalugaq qernartaq (the one that points to the sky).
On very rare occasions the male narwhal may also grow a second tusk, however this is extremely unlikely.... Most narwhal’s grow a single large tusk from the upper left side of their jaw, however around one in 500 males are known to grow a second large tusk from the right side of its upper jaw.
Female narwhals on the other hand rarely grow a visible tusk.
Because the narwhal is a marine mammal it is warm-blooded, produces milk, gives birth to its young and breathes air.
Manatee:
(https://www.livescience.com/27405-manatees.html)
Manatees are thought to have evolved from four-legged land mammals more than 60 million years ago. Except for the Amazonian manatee, their paddlelike flippers have vestigial toenails — a remnant of the claws they had when they lived on land. The Amazon species name "inunguis" is Latin for "without nails."
The name manatee comes from the Taíno (a pre-Columbian people of the Caribbean) word manatí, meaning "breast."
Manatees' eyes are small, but their eyesight is good. They have a special membrane that can be drawn across the eyeball for protection. Their hearing is good too, despite not having outer ear structures, because manatees have large inner ear bones.
Manatees' only teeth are called marching molars. Throughout a manatee's life, the molars are constantly replaced — an adaption to their diet of abrasive vegetation.
Manatees have only six neck vertebrae. Most other mammals, including giraffes, have seven. As a result, manatees cannot turn their heads sideways, and must turn their whole body around to look behind them.
Algae, photosynthetic organisms, often grow on manatees' skin.
Manatees never go on land.
Manatees don't always need to breathe. As they swim, they poke their nose up above the water's surface to catch a few breaths every few minutes. If they are simply resting, they can stay under the water for 15 minutes without taking a breath, according to National Geographic.
An animal that is similar to the manatee is the dugong (Dugong dugon). Dugongs are also in the order Sirenia, but they are in a different family, Dugongidae. These manatee cousins are found in the Indian and Pacific oceans. They have a notch in their tails, as well as tusks.
There are three species of manatee: the Amazonian manatee (Trichechus inunguis); the West Indian manatee, or the American manatee (Trichechus manatus); and the African manatee (Trichechus senegalensis). Their names indicate the regions in which they live. Typically, manatees stay in rivers, seas and oceans along the coast of several countries. The African manatee lives along the coast and in the rivers of western Africa. The Amazon manatee lives in the Amazon River's drainage, from the headwaters in Colombia, Peru and Ecuador to the mouth of the Amazon in Brazil... The West Indian manatee lives in the southern and eastern United States, although a few "vagrants" have been known to reach the Bahamas...
Today I learned that Dugong and Manatee are not the same family of mammals, but are in the same order (Sirenia). I had always thought they were the same. We have Dugong over here in the Indian Ocean. What I love about this species is that their ancestors further back in evolution were land-based elephantine mammals.