Animals whose blood isn't red (2021) | Hacker News Reader

Animals whose blood isn't red (2021)

animals.howstuffworks.com

67 pointswarrenm46 comments

Surprised there is no mention of lobsters, who, like crocodile icefish have colorless blood. For lobsters it appears blue once it comes in contact with oxygen [0].

0: https://www.fisheries.noaa.gov/national/outreach-and-educati...

Also they miss mentioning https://en.m.wikipedia.org/wiki/Erythrocruorin which is green, but for a different reason than biliverdin in lizards.

Seems it has chlorocruorin in which looks very much like a 'normal' haem (i can't spot the difference off hand).

edit: Ok, from Figure 2 here : https://biomolecules101.wordpress.com/2020/01/17/oxygen-tran... looks like normal heme ('heme b') has an ethenyl group while chlorocruorin has an aldehyde there

https://en.wikipedia.org/wiki/Blood#Color, straightforward and useful.

There is a condition called Sulfhemoglobinemia wherein you blood takes up sulfur instead of iron and your blood turns green.

Wikipedia says vulcans have green blood due to copper-based hemocyanin. Seems logical.

Everything about Vulcans seems logical.

Fascinating.

Interesting - a minor point, but the sulfur does not seem to replace the iron, but is just an -SH group on the haem.

Wow, that's an extremely green blood if Google's images are to be believed

Along a similar line, look into animals that don't sweat clear! Hippos sweat red, so they look like they're just covered in blood sometimes. Horses sweat white, so they look like they're just... well, you can go see for yourself.

I'm surprised hemocyanin isn't poisonous to us, or at least bad. Ingesting copper just doesn't sound healthy. AFAIC it isn't something we usually do either, so no pressure to evolve a way to metabolise it either.

We eat about 1mg of copper a day. It's an essential trace mineral. You can consume 10mg safely per day.

Huh. Didn't know. Thanks!

The term "essential minerals" refers to minerals (elemental rather than organic chemical compounds) required for life. For humans, those include five major minerals: calcium, phosphorus, potassium, sodium, and magnesium, and an additional nine "trace elements": iron, chlorine, cobalt, copper, zinc, manganese, molybdenum, iodine, and selenium.

(From Wikipedia: <https://en.wikipedia.org/wiki/Mineral_(nutrient)>)

Dose is critical. Whilst too little causes deficiency syndromes, too much of these compounds may also be harmful. Note that even excessive water consumption can be deadly.

Is this why blood has a metallic taste? It's literally metallic?

I'm pretty sure, yes.

I've never bought the official explanation for this. We have just four iron atoms per hemoglobin. But the roughly quarter-billion of these per red blood cell are in the red blood cells, which presumably haven't all suddenly lysed and dumped their hemoglobin.

I think we should test with blood plasma first. I'm thinking it is the various salts in the plasma we're tasting, not the iron bound up in hemoglobin which is itself trapped inside of red blood cells.

I was going to say, it's always been a more copper-y taste to me and that's what I usually read in descriptions of the taste.

I'd describe it more like an umami-rich sauce.

Which it is...

If you are a vampire.

Did some more reading, can't find much conclusive, you might be right, this reddit post is probably one of the better discussions

https://www.reddit.com/r/biology/comments/cqes9/why_does_blo...

Yes, iron. You can clearly taste it. That's one of the things I noticed after using a plasmacutter to cut through sheet, the vaporized iron stays afloat long enough that if you take off your mask and get a whiff it smells like blood.

I was under the impression the iron in the blood was in the form of hemoglobin. Does hemoglobin itself have a metallic taste, or is the taste caused by something else in the blood?

Good question I do not know but I associate the two (blood, iron vapor) very closely. It may well be that the blood also contains some free iron but Iron is so toxic that I doubt that would be enough to taste directly so it may well that haemoglobin itself tastes metallic but it only has a handful of Iron atoms in it compared to a mountain of other stuff.

I know we're not supposed to accuse anyone of trolling, but just admit it. :)

Yes.

Which of course leads to the inevitable sword-forging question.

Answer (possibly not suitable for some): <https://worldbuilding.stackexchange.com/a/78885>

This website manages to both hijack the back button and not show a single picture of any of the blood that the entire article is about. Fuck this website.

The horseshoe crab blood thing is always so interesting to me every time it comes up. Our society really has some very weak points.

How could they leave off Vulcans? Gross oversight

The next time someone insults me, I gonna respond: "Listen here, you green-blooded Skink!"

Minor yet important typo.

"Crocodile icefish frequent brutally cold portions of the sea where the water temperature can plummet all the way down to 28.5 degrees Fahrenheit (1.9 degrees Celsius). That's below the point at which fresh water freezes."

28.5F is minus -1.94C

would be great if there was an easy mnemotechnics to remember at how many degrees Celsius fresh water freezes

It's easy to remember, exactly 100 degrees below the boiling point.

it's just kelvins offset by 273.15!

<pendant>If we are allowing "to one decimal point" as "exact", and are taking about one standard atmospheric pressure, yes.</pendant>

Even at one atmosphere pure water can exist in its solid state at 0.01⁰C.

To be similarly pedantic, I think you may be looking for 'pedant' (a person concerned with fine detail) rather than 'pendant' (a hanging piece of jewellery or a hanging lamp) :)

Darned auto-carrot strikes again!

I doubt there's any simple way to remember that non-linear pressure vs. freezing point function for water.

> 28.5F is minus -1.94C

Myself, I don't throw stones.

yet ... -1.94 rounds to -1.9

Seems not so much a "typo" as a simplification/rounding

Also ... "28.5F is minus -1.94C"

Isn't right - "minus -1.94C" would be 1.94º centigrade

And that is distinctly above the freezing point of fresh water :)

...and yet not a single picture of the blood of any of them.

Right?! That'd be the first thing on my agenda if I wanted to write an article with that title.

I'll choose to believe the writers didn't especially have an interest, they were just paid to write.

If the news article contains "... caught on video" there's like 50% chance there will be video in that news article.

I didn't read the article, but the infinite scrolling experience, extremely long text and overall site appearance makes me question if this was written by a "journalist" or "author" at all. I might be wrong, sad then, but this page looks SEO 1x1, AI or not.

Manages to quiet down my interest sparked by the headline quite well.

The text seems fine. If it was written by an AI, it’s a very good one. I find it sad that a name as big as “how stuff works” has to resort to cramming their pages full of ads because there is no other realistic way to make money.

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