Wildlife Wednesday: Jellyfish and periwinkles

I was roaming along the river the other morning and found this jellyfish covered in periwinkles. I've never seen anything like it before but there were a few periwinkles on jellyfish but not as many as this specimen!

The river is starting to silt up again after being flushed open a few times in recent years. It's also been rather dry, so not a lot of fresh inflows into the river system. The water is getting murky, and there's quite a lot of brown algal growth and dying seagrass weed.

We had an influx of jellyfish in the river the last time it opened to the sea near me (it opens further around usually, but in flood it also breaks open here). There were hundreds of the round jellyfish with tentacles, and quite a few reports of people being stung by them, however, I hadn't been.

Jellyfish with tentacles

So, I googled and found out about these tentacled jellyfish. They're jelly blubbers (Catostylus mosaicus) and there is more information from Australian Geographic, here.

There has always been a few of the crescent shaped jellyfish, but there have been quite a lot more of these lately too.

OMG! I googled again. These crescent-shaped things aren't jelly fish but egg masses laid by moon snails. Holy cow! All my life I've had that wrong - imagine that! LOL!

This article is from SA, but relevant here in NSW, I hope! Read about egg masses here. And here's one from Victoria, here.

I started wondering if the shells on the egg mass were moon snails and not periwinkles...but I haven't been able to find that yet.

My mind is blown. I'll have to look later after I recover from the shock of that not being a jellyfish!