Do insects have hearts and other questions.

I woke up this morning wanting to know whether insects have hearts. I’m a bit of a freak, aren’t I? Do other people wake up wanting to know stuff, or do they just want a cup of tea and a wee? Yes, but not necessarily in that order I guess.

I annoy my husband tremendously because I go from sound asleep to wide awake, itching to get up and engage with knowledge, faster than a Ferrari can drive to our village Tesco. I hate Tesco, but that’s a whole other blog.

Thank heavens for Google then. No sooner had I dried off after my shower, and while my poor husband was still lying in bed with a book and a cup of tea and the dogs for company, I had managed to uncover a wealth of fascinating facts that I never knew before.

Insects DO have hearts! Who knew? In fact, they sometimes have more than one. Apparently, some insects have an open circulatory system meaning that their blood is just sloshing around in their little bodies and not contained in blood vessels, which is where we and other vertebrates cunningly keep ours. The heart in an insect can often be a simple and long muscular tube that runs the length of the body. Those insects that do have several hearts locate the extra ones in bits that their major heart cannot reach (Heineken hearts anybody?), so for example, wings and antennae and that sort of critterly thing. Ewww.

So that led me to look at other heart facts. Well, you know how it is, Google, cup of tea, Sunday morning …. I couldn’t resist.

The animal with the largest heart proportionally is the Humming Bird. Its heart is 2% of the mass of its body. Wow! It needs to have a large heart so that it can beat as fast as it does and to keep the oxygen pumping so that it can flap its wings between 12 and 80 times per second. I can’t do anything 12 times per second. *jealous* It also has the fastest metabolism of any creature. So they are stunningly beautiful, slim and can eat what they want! Little bastards!

Several creatures with more than one heart include *gulps* the octopus, which has three hearts for the same reason that an insect needs more than one heart, so that the blood can reach the tentacles. I have a real aversion to octopi I’m afraid. They make my back go to jelly. Argh! Furry ones are cute, cartoon ones are sweet; the real thing though… *turns green and groans*

Earthworms seem to either have five hearts or five pairs of hearts. Google wasn’t clear on this and I couldn’t be bothered to delve much deeper than that so I apologise for my poor research! These hearts are spread out through the segments.
The land animal with the largest heart is the giraffe. That has to be the case doesn’t it? Giraffes are just so ridiculously gorgeous. They have really huge soft brown eyes and fabulous eyelashes. They eat leaves and don’t kill things. It makes sense that they have big hearts.

The animal with the slowest heart beat appears to be the crocodile that has a resting bpm of 1 at a temperature of 10 degrees Celsius (which, trust me on this, is the coldest a crocodile ever wants to be).

The animal with the biggest heart is, of course, the Blue Whale. While its heart is only 0.5% of its total mass, it still manages to be the size of a Volkswagen Beetle anyway, and can weigh anything from 600kg to a ton, which is what you would expect from a creature that is 108 ft. in length and weighs around 180 tonnes. The Blue Whale’s heart has a rate of 12-20 bpm, and while in 1911 it is estimated that Blue Whales numbered 250,000 or so, since then they have been hunted virtually to extinction. A 2002 study showed there were only 12,000 Blue Whales maximum but that number seems to have grown again to current estimates of approximately 25,000 or a tenth of their population a century ago. Japan, Norway and Iceland still hunt them and approximately 20 are killed every day.

So, it’s easy to figure out which animal has the coldest heart isn’t it? That would be the human.