Yes, it’s a day late. Dr. Free-Ride and Dr. Free-Ride’s better half are currently engaged in sprog retrieval maneuvers at the home of the Grandparents Who Lurk But Seldom Comment. What follows is this morning’s attempt to get the Free-Ride offspring to tell us something science-y.
Dr. Free-Ride: Were there any things you noticed while you were away from us that you think might have to do with science?
Younger offspring: I noticed that when I go in the ocean, the salt water makes my eyes red, and I wanted to know why.
Dr. Free-Ride: That sounds like a reasonable matter for scientific enquiry.
Dr. Free-Ride’s better half: Why do you think your eyes turn red?
Younger offspring: Because your eyes are being disturbed.
Dr. Free-Ride’s better half: But why is it they turn red rather than some other color? Why not blue or green or purple?
Dr. Free-Ride: What else in your body is red?
Elder offspring Red blood cells!
Younger offspring: Does salt water make my eyes red with blood?
Dr. Free-Ride: I’m guessing that when the salt water is stinging your eyes, little capillaries in the eyeball might burst.
Younger offspring: But why does salt water sting my eyes?
Dr. Free-Ride: Well, tell me what you’ve noticed.
Younger offspring: I go in the water to swim or jump waves, and even though I wear my goggles, a little bit of water always gets in. It stings my eyes and makes me want to go up to the shore and close my eyes a bit. And I have to go with the wave, so that means I have to turn as the waves come so more water doesn’t go in my eyes. Because it’s salt water.
Dr. Free-Ride: My hunch is that the irritation might be related to the concentration of stuff in the seawater compared to the concentration of stuff in your eyeball. Do you remember when I explained how salt melts snails.
Younger offspring: Kind of. Show me the pictures again.
Dr. Free-Ride: OK, so the idea is that water is small enough to travel through the membranes, and it travels in the direction that will make the concentration on salt (and other dissolved stuff) on both sides of the membrane the same. Because there’s some stuff dissolved in the water in your eyeball, this means pure water will sting your eyes, too.
Younger offspring: It will?
Dr. Free-Ride: Because look, the water will move into the eyeball to try to dilute the stuff dissolved in there, and then there will be extra water, and the eyeball will swell.
Younger offspring: Ow!
Dr. Free-Ride: But if the water outside the eyeball has more salt (and other stuff) dissolved in it, water will flow out of the eyeball to try to dilute the sea, and I think that would make your eyes hurt, too.
Dr. Free-Ride’s better half: I’m not sure about osmosis. The salinity of the body is pretty close to the salinity of the ocean, isn’t it?
Dr. Free-Ride: What about the eyeball?
Dr. Free-Ride’s better half: Hmmm.
Dr. Free-Ride: So, what about the redness? How do you explain it?
Dr. Free-Ride’s better half: Huh, does it have anything to do with the pH of seawater?
Younger offspring: I want to study it before you write the Friday Sprog Blog about it. [RMD] could take me wave jumping, then you can photograph my eyes after, and maybe we can study what happens inside the eyes to make them red from salt water.
Dr. Free-Ride: Kiddo, we can definitely study the matter further, but we’re already a day late with the post. People can deal with the preliminary observations and theorizing for now.
* * * * *
Dr. Free-Ride: What about you — have you been thinking about any questions with a science-y flavor to them?
Elder offspring Sure.
Dr. Free-Ride: Is there one you can share with me this morning?
Elder offspring Why animals walk on their toes.
Dr. Free-Ride: When were you thinking about that?
Elder offspring When we went on our walk this morning.
Dr. Free-Ride: What made you think of that question?
Elder offspring The kitty. When she sits down, her feet seem bigger than when she’s walking.
Dr. Free-Ride: Have you noticed other animals that are like that?
Elder offspring Yes. Bunnies, dogs, and I think squirrels.
Dr. Free-Ride’s better half: Dolphins?
Elder offspring Dolphins don’t have feet!
Dr. Free-Ride: Do you have any theories about this?
Elder offspring Animals walk on their toes to get more balance (and they use their tails to get a better sense of balance, too).
Dr. Free-Ride: But when I walk on my toes, my balance is worse.
Elder offspring Well, animals have shorter legs than ours.
Dr. Free-Ride: Proportionally anyway.
Elder offspring From what I’ve read, bears are the only animals that stand upright on two flat feet besides primates.
Dr. Free-Ride: Bears also like eating junk food.
Elder offspring But I think bears have short stubby tails, not long ones; maybe that’s why they do it. Also, I read that they stand upright to get a better look.
Dr. Free-Ride: Any other science-y stuff you noticed and wanted to talk about?
Elder offspring No, not really.
Dr. Free-Ride: Well, you’re about to spend the rest of the summer with your parents, so that’s going to change.
Elder offspring I know.