Blog 5 would handle another eartshot. I wrote blog 3 and 4 about water, now it was time to start exploring the air. However, because water is so intriguing – probably secretly my favorite – I write two bonus articles about a sea animal that crosses our oceans. After the corals of blog 3 and 4, now the whales (cetacea), possibly the most amazing animals on this planet earth. Allow me to try to convince you.

This first paragraph should in fact suffice. The blue whale, one of the approximately 90 whale species, is the biggest animal to have ever existed on this earth. They are 2700 times bigger than us, 40 times bigger than an elephant and 30 times bigger than the largest dinosaur, the T-rex. Immense. If this specie would have been, 66 million years ago, suddenly erased from the face of the earth due to a comet strike, there would have been countless blockbusters dedicated to its mythical existence.

Cetacea are defined as big placental sea mammals with a hairless streamlined body, a horizontal tailfin and a blowhole at the top of their head to be able to breathe at the water’s surface. This last feature leads to gorgeous images.
This family is categorized into two subgroups: the baleen whales (mysticeti) and the toothed whales (odontoceti).

The mammals of the first subgroup, the baleen whales to which the blue whale belongs, are larger than the mammals from the second subgroup. They have baleens growing down from their upper jaw which they use to filter from the water large volumes of small food (plankton). They have 2 blow holes and are extremely loud: with a for the animal kingdom record noise level of 180 dB they sing in low frequency (30 – 8000 Hz). Their songs (there are many recordings that can be found online, worth a listen) are both for communication and orientation purposes and their sound can, when voiced at the right depth, travel up to 16 000 km (10 000 miles). Professor Christopher Clark of the Cornell University explains that the whales would use their sounds for ‘echomapping’: by sending their signals and waiting for its return they map the oceans and its shores. With a hydrophone installed in Virginia (East coast of the USA) his research team can hear the song of a whale swimming near the coast of Ireland. The distance between those two places is 5500 km (3400 miles). That is incredible.

Already convinced? If not, then I continue. The mammals of the second subgroup, the toothed whales, have teeth and hunt for fish and other mid-sized sea life. Dolphins are a part of this family (all dolphins are whales) and the orca or killer whale is the biggest dolphin. Also the less known porpoises are toothed whales. The toothed whales have only one blow hole, but are similarly loud as the baleen whales, although they are noisy at higher frequency. Some species can generate and receive sounds up to 160 000 Hz. As a reference, for those of my generation who can still remember the “secret” ringtone we could hear as a 15-year-old while the teacher couldn’t: this one has a frequency of 17 000 Hz. The toothed whales use their sounds for communication as well as for ‘echolocation’: a sent signal bounces off of for example prey to which they consequently can determine the distance. The system is extremely ingenious and has thus been subject to research for multiple decades. Dolphins are even being trained by defense departments to amongst other things assist with identification of underwater mines. They perform this task with utmost precision.

In case further argumentation would be in order. Whales are true world travelers. There are species that travel from the equator to the furthers northern or southern parts of the world and back in the same year. This family of mammals thus adds to their record list, apart from being the biggest and the loudest, also performing the longest mammal migration in the world.

And oh yes, there is something else. Like all mammals whales have lungs. What is difficult to then comprehend is that they are also divers, deep sea divers. There comes record number four: the deepest dive of a mammal recorded by us was performed by a Cuvier’s beaked whale and was 2992 m deep. Other mammals do not even come close to this record number. On average whales are diving for about an hour, but the up till now longest registered dive lasted 222 minutes (more than 3.5 hours). To be able to withstand the water pressure on the lungs deep underwater, whales would purposefully collapse their lungs. Collapsed longs come with a couple of advantages for mammals that our spending time under water, but it also results in a lung capacity of literally 0 l and thus no potential oxygen transfer to the blood at the alveoli (there where the lungs transfer O2 and CO2 with blood). Whales can however, compared to humans, store more oxygen outside of the lungs: they have 2x more hemoglobin, the protein that transports oxygen in the blood, and 10x more myoglobin, the protein that stores oxygen in the muscles. Additionally, they would temporarily stop the blood flow to different organs such as kidneys and the liver. This conserves energy and thus reduces oxygen consumption. Their heartbeat slows down as well and they fold their fins to be able to slide even more aqua dynamically through the water.

All thus pretty cool. And on top of that they could be of assistance to help us rebalance our shared climate. That is story for blog 6.