Question: What is a tardigrade (water bear) and why does it look like an airbag? Also because it is microscopic, does that mean that it’s heart would stop quicker that anything else?

Samuel Vennin answered on 12 Jun 2018:

That is an original question! I have to admit I have never heart of water bears or tardigrade (thought it was the newest version of Doctor Who’s TARDIs…). From what I read on the internet, they have a different way of breathing, hence to import oxygen in their body. This might mean that they have no heart nor blood since their main function is to bring oxygen to our muscle so that we can live and function properly. Water bears bring in oxygen using other methods.
https://www.quora.com/Do-tardigrades-have-heart-blood-and-do-they-respirate

As for the way it looks like, I would say it looks more like a shrimp without antennae. Usually, animals evolve to survive so I guess tardigrades look the way they do because they realised this was the best way not to die. An airbag, as you say, seems indeed to be a great thing to look like if you want to survive…