Last Friday I gave you this object to have a go at identifying:
It was not an easy one and I was hoping that nobody would work out what it was, but as usual some of you managed to figure it out. So, big congratulations to cackhandedkate and Jake who suggested the surface of a tongue and henstridgesj for working out that these 2mm hooks are from the tongue of a cat – a BIG cat.
These are in fact the barbs or aculei from the tongue of a young Tiger Panthera tigris (Linnaeus, 1758)
This small sealed box has no date associated, but the style of the label and the number suggest that it probably one of the early specimens acquired by Frederick Horniman before he built the Horniman Museum, dating to 1886 or perhaps earlier.
The aculei on cat tongues are interesting adaptations not seen in other carnivores (at least none that I can find any information for). The rows of hooks are ideal for grooming – like a stiff brush, but they are also a useful tool for removing meat from bones.
This is particularly handy when you have a relatively short face with incisors that form a broad straight row for clamping windpipes shut, unlike the narrower incisor row that you find in the dogs, which act a bit like like tweezers for removing meat on bone.
The aculei are made of keratin, the same protein that claws, hair and horns are made from. It may seem quite difficult to evolve lots of small claws on your tongue, but you might be surprised to know that the cells that secrete keratin (called keratinocytes) are the the most common cells on the surface of your skin (including your tongue) where they play an important role in fighting infection and repairing damage.
In order for these cells to secrete enough keratin to grow a small claw, they need to get a bit bigger so they can secrete more of the protein. They also need a simple mechanism that gives the resulting structure a useful shape.
Mammalian tongues are already covered in little structures called ‘papilla’, with three types containing taste buds and one type, the filiform papilla, that provide grip on the surface of the tongue, making it easier to eat ice-cream. It’s these filiform papilla that have adapted in the cats to make a structure with enough grip to lick the meat off a bone.
I’m actually a bit surprised that more mammals don’t have tongue barbs like cats, although there are other animals out there that have specialised tongues with other keratinous structures, like the horny tips of Woodpecker tongues and the tiny bristles of some Fruitbats.
Still, nothing says ‘obligate carnivore’ like a tongue covered in sharp hooks. Considering the length of the aculei I wouldn’t fancy being licked by a Tiger – their tongue looks like it could take human skin right off. However, it has given me an idea for how to quickly and easily remove wallpaper using a Tiger and a bucket or two of Bovril.