Golf Ball Sponge - A Trypophobe's Nightmare

Image: California Academy of Sciences

Holes! Holes in a thing! Some people really hate to see holes in a thing. It makes them feel uncomfortable and itchy and a little sick. For some people, holes in a thing is positively unholy. Oddly enough.

My mind wanders and I imagine animals defending themselves against humans by biting into a chocolate bar to expose the delicious, honeycomb centre. Hunters cower at the sight like vampires confronted with the crucifix.

Image: WoRMS for SMEBD

There's been research into trypophobia which suggests it may have something to do with the the spotty patterns of venomous animals. It's become one of those evolutionary things which was useful in its day but is now a blight on our lives, a horrible growth which drags us into the dark past and away from beautiful tomorrows. Like, I don't know... an ex-wife or something.

In the case of Golf Ball Sponges, it's not the holes you need to be careful of.

Image: Nick Hobgood

There are dozens and dozens of species in the Tetillidae family, found all over the world and almost all depths of the ocean. Like any other sponge, they have a kind of skeleton made of tiny spicules of various shapes and sizes.

Long, needle-shaped spicules stick out of the Tetillid's surface such that it looks quite fuzzy. If you touch it, you can easily end up with sharp spicules stuck in your skin like splinters.

Image: Bernard DUPONT

These needle-like spicules can get covered in silt and assorted muck from the sea floor, so it's a good thing the hole bits don't have them. These pits are known as porocalices, and its through these that the sponge draws in water to filter out microscopic food.

Image: WoRMS for SMEBD
Spicules of Cinachyrella arabica
D: sigmaspires

Tetillidae belongs to the order Spirophorida, which means they also have weird, S-shaped spicules called sigmaspires.

Image: WoRMS for SMEBD
D to G: two kinds of megacanthoxea
H is just an oxea

And some Tetillids have another unique spicule called megacanthoxea, which means they're big, spiky oxea.

Most Golf Ball Sponges are pretty much spherical and covered in pits, but there are some that are more irregularly shaped and some have just one pit.

Image: National Museums Northern Ireland
Glories in the name Tetilla cranium

Tetillids of the genus Tetilla, the one after which the entire family is named, have no pits at all. So there's some respite from the horror!