Wednesday 22 June 2016

Jellynose Fish

WARNING: High concentration of gelatinous material in the schnozzle area.

It helps protect them against, erm... bumping into stuff? I guess?

Ateleopus tanabensis
Ateleopodiformes is a tiny and rather mysterious order containing just a dozen or so described species spread across four genera. Small ones reach little more than 30 cm (a foot) long, several others can reach 2 metres (6.5 feet).

They live in the deep sea! Not too deep, though, and they still like it warm. Rather than live in truly abyssal depths they prefer to hang out on continental slopes in tropical regions around the world.

Ateleopus japonicus
Jellynose Fish are also known as Tadpole Fish because they're usually rather front-heavy, with a big head and a long, spindly body that tapers away to nothing. Their pectoral fins look like Chinese fans decorated with a picture of an overcast or smog-filled sky (ie. they're completely grey or brown). They also have a perky dorsal fin and a long anal fin that runs all the way down their tail.

Ateleopus means 'imperfect foot', a name which refers to their pelvic fins. In most adult Jellynose Fish the pelvic fins disappear almost entirely. They each become a single, long ray that dangles from their neck like an undone tie.

One genus called Guentherus is a little different in that they retain their pelvic fins. It's just that the actual 'fin' part is really small and several rays are extra long so that they dangle from their neck like three or four undone ties. These rays are presumably sensitive enough to help the Jellynose find tasty crustaceans and stuff hiding on the sea floor. After all, it can't be easy to sniff anything out with your nose packed full of gelatin.

Speaking of which, what's up with that jelly-nose?

Image: NOAA Okeanos Explorer Program
Well, think of cartilaginous fish like sharks and rays. One of their big characteristics is that they have no swim bladder. This is a bit of a problem because swim bladders are gasbags that other fish use to control their buoyancy. Without it, sharks and the like have to use other methods to stop themselves from simply sinking. And so they have skeletons made of cartilage rather than heavier, denser bone, and their enormous livers are packed full of fats and oils that are less dense than sea water.

Jellynose Fish aren't cartilaginous fish but they share with them the problem of having no swim bladder. This, again, could be a bit of a problem. They get around it in two ways. First, their skeleton is mostly cartilage, just like with sharks. Second, they got jelly. Lots and lots of jelly. It's all over them! Their very flesh is soft and gelatinous to stop them sinking. It works great so long as they don't try to exert themselves too much; they simply haven't the muscle power.

And why the concentration in the schnozzle region? I guess they're simply THAT front-heavy!


TexWisGirl said...


Esther said...

I just want to *boop* their adorable little noses!

Joseph JG said...

I so agree! I'm sure it would be a wonderful experience