Diving that time of month

[vladimir]

It's got uterine lining in the blood as well. It's not just blood that comes out.

That's what I wrote and deleted a couple of posts earlier.

DAN seems to think that there's not enough blood:

The average blood lost during menstruation is small and occurs over several days.

and that they are not interested anyway:

Also, it is known that many shark species are not attracted to the blood and other debris found in menstrual flow.

But they mostly rely on the paucity of attacks, which wouldn't comfort me that much:

Are women at an increased risk of shark attacks during menstruation? There are few reported shark attacks on women, and there are no data to support the belief that menstruating females are at an increased risk for shark attacks.

I doubt endometrium is a shark repellent, and I think that sharks are pretty good at discerning blood amid other scents. One theory, based on my very limited knowledge of physiology, is that the blood that is released in menstruation has left the capiilaries a while ago, pooled in the uterus, and eventually released. Therefore, from a shark's perspective, it is not "fresh." Just a theory. Most sharks are happy to scavenge though, so I don't see why they'd demand fresh blood.

 

[Sea Lioness]

The reason that sharks are not interested is because the blood discharged in menstruation is composed of older, dead blood cells, rather than the live blood cells that would come from the circulatory system as a result of an injury. Sharks prefer "fresh" prey, meaning an animal that is still alive (& possibly weakened by injury), or very recently dead. Consequently, sharks are attracted to injury blood. Sharks have extremely good senses of smell, and can tell the difference between menstrual blood and injury blood. Because menstrual blood does not contain those fresh, live blood cells, it doesn't attract the sharks.

 

[fjpatrum]

The reason that sharks are not interested is because the blood discharged in menstruation is composed of older, dead blood cells, rather than the live blood cells that would come from the circulatory system as a result of an injury. Sharks prefer "fresh" prey, meaning an animal that is still alive (& possibly weakened by injury), or very recently dead. Consequently, sharks are attracted to injury blood. Sharks have extremely good senses of smell, and can tell the difference between menstrual blood and injury blood. Because menstrual blood does not contain those fresh, live blood cells, it doesn't attract the sharks.

Why do sharks respond to chum made from frozen fish then? I mean, those aren't "fresh" injuries, though I have no idea whether there is a difference between "fresh" and "fresh frozen".

(Some "chef" told Chef Ramsey on "Kitchen Nightmares" that everything was fresh frozen and it made me laugh. This is the first opportunity I've had to use the term though in a slightly different context. )

 

[g1138]

Why do sharks respond to chum made from frozen fish then? I mean, those aren't "fresh" injuries, though I have no idea whether there is a difference between "fresh" and "fresh frozen".

(Some "chef" told Chef Ramsey on "Kitchen Nightmares" that everything was fresh frozen and it made me laugh. This is the first opportunity I've had to use the term though in a slightly different context. )

Fish oil my friend
This is why I don't take cod liver pills during dive days....that and also because I don't want to ruin my visibility, if you catch my drift

 

[g1138]

The reason that sharks are not interested is because the blood discharged in menstruation is composed of older, dead blood cells, rather than the live blood cells that would come from the circulatory system as a result of an injury. Sharks prefer "fresh" prey, meaning an animal that is still alive (& possibly weakened by injury), or very recently dead. Consequently, sharks are attracted to injury blood. Sharks have extremely good senses of smell, and can tell the difference between menstrual blood and injury blood. Because menstrual blood does not contain those fresh, live blood cells, it doesn't attract the sharks.

Not true, ever see the vid of a great white chomping on a dead whale carcass?

Sharks will find food in the following order, starting with farthest distance to closest:
Far
- Hearing
- Smell
- Vison
- Lateral Line sensing
- Electroreception
- Touch & Taste
Close

What they are interested in depends on the species and possibly even the individual.
They don't really know what they're sensing until they see it and touch it. But they probably can take a guess if it's their usual food groups.
As for us, we make lots of noise in the water, we're big, we're clunky and clumsy. You wouldn't immediately eat a cow that acted like that would you?

 

[Sea Lioness]

Why do sharks respond to chum made from frozen fish then? I mean, those aren't "fresh" injuries, though I have no idea whether there is a difference between "fresh" and "fresh frozen".

The reason we freeze meat to store it is to prevent it from decaying in the normal process that would occur if we didn't freeze it. I would guess that the blood cells from an animal that was stored cold and frozen relatively soon after its death would probably be in a state similar to what they were in when they were frozen, and smell as such.

Menstrual blood has been stored in a warm body for a while before it is discharged, and the cells have had time to decay.

There are probably other chemical differences between menstrual blood and injury blood as well, which sharks, with their great senses of smell, can distinguish. I'm sure the information is out there for anyone really interested in blood chemistry, but the main point is that menstrual blood does smell different than injury blood, and there is no evidence that sharks are attracted to menstrual blood.

 

[Sea Lioness]

Not true, ever see the vid of a great white chomping on a dead whale carcass?

I am not an expert on great white sharks, however I would suspect that the sharks are eating a whale carcass that is relatively recently dead.

 

[seaducer]

Sharks are not attracted to menstruation blood because it is human blood, and not something that sharks would ordinarily key in on.

The other elements of the discharge may be more interesting to a shark for curiosity sake, however there simply is not enough of any of it to be of any interest.

Studies have shown that human blood in anything less than life threatening amounts is unlikely to bring any serious attention from sharks, while shockingly small amounts of fish blood turn their heads instantly.

Sharks that prey on sea mammals might have different ideas, since mammalian blood is similar enough that they would recognize it for what it is...however still the amounts of even the worst day you have ever had is not enough to be of concern.

Some of the whale carcasses that white sharks have been filmed gorging themselves on are so putrid and rotten that most boats would not get within 100 feet upwind of it. They will greedily feed on some pretty nasty stuff indeed.

I've been bleeding bad enough to see it while surrounded by sharks and have noticed nothing in their behavior that suggested they noticed.

 

[tddfleming]

I've been bleeding bad enough to see it while surrounded by sharks and have noticed nothing in their behavior that suggested they noticed.[/QUOTE]

From your "aunt flow?":shocked2:

 

[Crowley]

This discussion always ends up going around in circles and it always ends up on whether or not menstruating women are more likely to be eaten by sharks - so to briefly summarise the points for the OP (okay I'm a guy, but my ex-gf was also an instructor...)

- Unless you are otherwise incapacitated by your period (i.e. severe stomach cramps, nausea etc.) then diving is not a problem
- Any increased risk of the bends before, during, or after your period is negligible, at least for recreational diving.
- Use whichever method you prefer to use dry - personal comfort is important whilst diving and you know your own body and whether or not you need to change your tampon or pad after a dive.
- Sharks are not going to eat you if you are on your period. I would suggest (with my tongue in my cheek) that a PMSing woman is a FAR more dangerously aggressive predator than your average man-eating shark!!
- please do not bite my head off for saying that if you are currently PMSing.

If it was a major issue, half of my colleagues would have to stay out of the water for a few days every month, or would have been eaten. I do have one friend who has very debilitating periods sometimes, and she is excused by the management of my dive centre.

Hope that helps,

C.