Animals with holes in them - are there any?

A while back, I stumbled across a picture of a horse that had apparently sustained some kind of injury that resulted in its neck healing with a hole right through it from side to side.

Warning: here comes a picture of the above-described phenomenon - it’s not gory, just weird, but I’ll de-linkify it so that nobody can complain they accidentally looked and it spoiled their afternoon nap.
http://oddanimals.com/funnyanimals/horsewithopenholeinneck.html

-Apparently, this really is a genuine photo, not a photoshop - if so, it should be noted that the horse’s spine will pass through the lower section - the upper section being muscle and other soft tissues.

But even if it is fake - I don’t want that to detract from the question here, which is:

What animals, if any, naturally have holes in them? And for the smart-arses, I’m not talking about the sort of holes that have a mouth at one end of them - I don’t think I even really mean the sorts of holes that fish have for their gill covers - although that’s closer, because I’m looking for animals that naturally have holes through which daylight can be seen without any trouble - are there any?

The alimentary tract that runs through many creatures from mouth to anus constitutes a “hole” in the topological sense of being equivalent to a torus. But no, I’m unaware of any creatures that are effectively doughnut-shaped.

Noted in my last paragraph.

I’d accept things where it’s not a soft/living body part (for example perforated frills on a crustacean’s shell, if such things exist anywhere.

How about a keyhole urchin, also called a keyhole sand dollar?

I think those holes have flesy appendages poking out of them when the animal is alive. If we were just looking at skeletons, there would be lots of candidates - including humans.

Here’s a live sand dollar. It appears that you can see through the holes, even when alive.

I’m not sure - I think the sand you’re seeing in that picture has just fallen in the top of the opening.

In this one you can pretty clearly see hand through a few of the holes.

FYI: that horse’s rescue was featured on Animal Cops: Houston. I think it’s still in occasional rotation on Animal Planet. It’s definitely real, and it’s definitely weird.

Thanks for that - you’re quite right. The description on Wikipedia doesn’t make this at all clear, describing them as pores that take in water.

Yup. I’ve seen that show. Can’t remember exactly how the horse wound up with that hole but I believe it was an injury that was never properly treated and eventually healed on its’ own.

Some of the ceratopsian dinosaurs (kin of triceratops) have holes in the shield bone that covers their neck. It’s hard to be sure, of course, but some paleontologists believe that those holes were open, not covered by skin.

There’s a show called “Animal Cops”? Seriously?

When I was about 10, I saw a strange creature under a tree in Massachusetts - looked like a large caterpillar, and had holes all along its length, giving it the appearance of a ladder. It was moving, bending back and forth in a quick, repetitive motion. I watched it for a long time, astounded, then left and when I returned it was gone.

I know I was just a kid, but I swear this happened, and I’ve always wondered about it.

Not really an answer but a thread like this can’t go without mention of the cow hole.

Your statement reminded me of something a friend of mine said once (he may have been quoting someone): “In the topological sense, a human being is the same shape as a record album: A solid with one hole through it.”

Interesting notion. And no, I can’t think of an animal with a hole running through it. Hell, I can’t even think of a plant with a hole running naturally through it, though plants can be grafted into weird shapes with closed holes. People put holes through themselves all the time, of course, in the form of piercings. But as for naturally occurring holes, I’m stumped.

Don’t some lizards or chameleons have a hole through their head? I seem to recall seeing something like this at a pet store once. I could be mistaken.

Sorry, just a scant memory.

Plants are easy. The kind of splitting and grafting that is used to create decorative trees can happen spontaneously in nature - I’ve seen trees where a branch has a side branch that must have originally just been pressed hard against the trunk, but is now a fused whole. I’ve also seen what must have started out as a hedgerow, but matured into an untidy fence of twisted, fused and intertwining wood, complete with holes.

And there are plants with naturally perforated leaves.

This is related to holes in animals like the horse you describe. Dr. William Beaumont studied digestion on Alexis St. Martin. Martin had a wound that would not heal after being shot. Article about the doctor and this man.

Martin

I can’t help thinking that sounds like two caterpillars with their feet (or false feet) placed together, or something like that.