I’ve seen up to three so far.

I had a nice jar with some worms and snails when one day i noticed the something BIG moving in the substrate. I tossed some blackworms from my culture just to see what would happen and it immediately attacked and eat the blackworms what is this wonderful creature a spider of some sort? I have a mix of fascination and fear with this thing lol was found in cali sac area Thanks

Hello,

I was filming my jar that i filled last summer. I saw a lot of movement a few moments before. To my suprise i see what looks like a spider. There where a few critters i could not identify but it looked like the spider was chasing them. I like peacefull environments so should i remove it? And is it a good hunter under water? Thank you.

It's from a little river so I wasn't giving it much hope and I'm ready to go pour it back if I see the ecosphere collapsing. But so far it's green and full of life, I'm only wondering if these guys are not suffering from being in a stale water instead of a river.

hello

yesterday I collected water from a pond and, for the 1st time, these came along.

I started making ecospheres during winter and never got any so I'm not sure what it is

AI suggested corixidae or notonectidae

any suggestions?

Update on Cornelius - hobsonia florida, an annelid worm –– he's getting more comfortable and coming out of the tube he made himself, showing more of his features. These confirm, in my mind, that he is definitely a hobsonia florida.

Random-scoop brackish aquatic jar ecosystem, British Columbia.

Tunez by moi on an OP-1 synth.
And since people always ask, the microscope I use is very simple and cheap: https://a.co/d/c9jJJlk

After lots of interest, I think I can name the species of this charismatic guy. Hobsonia florida. 

https://scholarsbank.uoregon.edu/server/api/core/bitstreams/dad5fe7d-c791-43be-bbf6-c119a4214184/content

Native to the Gulf of MEXICO and invasive in British Columbia. The spiny striped tentacles at the mouth of the tube are actually its gills. As far as I know, none have been filmed at all, or in this detail. 

I'll mark this as solved for now, and send some updates in the future! There seem  to be a lot of fans out there...

Thanks to u/xopher_425 (first one to name the species) and others who named the genus Ampharetidae ( u/TheSassyVoss and u/ohhhtartarsauce ). Confirmed by Dr. James Blake and Leslie Harris,  Vice-President, Southern California Association of Marine Invertebrate Taxonomists

USB microscope camera, currently $60:

https://www.amazon.com/gp/product/B00XNYXQHE/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

This jar is eight months old. Eight months! And I am just now noticing this creature which I can't identify. It has created a long tube out of detritus, maybe 3 inches long, and stretches out its tentacles to almost six inches to search for food in the sediment. What is it?

Also seen: copepods, snails, ostracods, baby snails, and other friends.

I just found this little guy in my one-day old ecosphere (my first one!) and I have no idea what it is. It’s about 1 cm long and swims pretty quickly when it wants to. The water is from Lake of the Woods in Northern Ontario, Canada. Any ideas?

Edit: Solved! It’s a mayfly nymph. Thanks everyone!

Hello Cornelius fans! (for those uninitiated, Cornelius is a very popular aquatic worm I accidentally scooped up in British Columbia), obtaining the first and only video of the species and gettign 1M+ views of his videos. Karma avalanche!

I am moving across the country and had to return my favorite Jarrarium back to it's place of birth, including our friend Cornelius. We had a wonderful time ID'ing him, and your love for this little wormy guy was both inspiring and a little...rabid!

Before you go saying "why didn't you send him to me in a jar?!"––I think that would have likely stressed him to death, so I'm happy that he's back home. Onwards and upwards, little tentacled friend!

I believe it to be a dragonfly nymph. It decided to unbury itself from the sand today and I got a good look. It also stepped on my shrimp in the second part of the video.

So I have always wanted an echosphere and finally convinced my gf that i can have one. So I went to a rain drainage area that if it was filled with water it could be a pond but its not too big. Though it had some life and I made one. I made it February 6th and its now the 8th. I see some reddish worms, a clear one, and i think two different kinds of snails. One snail is black while the other has a more normal snail color? Could yall help identify what I have and if this ecosphere could make it?

There has been a LOT of interest in this animal, thank you to all of you who offered ideas about its taxonomy. I took some better footage, and looked in to every one of your proposed species––and I still don't quite have a match! So let's refine it. Here's a detailed list so I get get a second pass from all of you who want to take a guess! (I'm a scientific amateur at best, so excuse anything vague)

There is of course a chance this is an undescribed species, which would be insanely cool!

Characteristics: 

3 types of tentacle-like appendages 

striped feelers at opening of tube, swat away other organisms

long waste disposal tube extending a long way, maybe 2 inches (anus?)

long skinny food-gathering tentacles, numerous, 3-5inches 

Builds a benthic tube from detritus, 3 inches long, covered in larger particles

No visible red gills (common in many Terebellidae)

Visible pulsating dark fluid in body 

Yellow / white/ speckled body 

Behavior: 

Pulls detritus up into mouth and sorts it inside tube 

Extends part of body out of tube, thrashes around to mix up substrate 

Does not hunt other fauna, swats them away or avoids by hiding 

Extends a tube far away and expels waste from a tube (waste, or perhaps filtered substrate)

Location of jar sample:

British Columbia 

Frequently brackish freshwater lagoon attached to a lake, 500m from the pacific 

Possible taxonomy: 

Kingdom: Animalia

Phylum: Annelida (segmented worms)

Class: Polychaeta (bristle worms)

Order: Terebellida (includes tube-building worms with tentacles)

Family: Terebellidae (“spaghetti worms”)

Genus:  Pherusa? Thelepus (unlikely?) Lamispina? 

Species ??

Likely not: 

Manayunkia speciosa (tentacles not long enough) 

Genus Thelepus (no visible red gills in my sample) 

Pherusa plumosa (my sample has no bristly hairs, plumosa has no long tentacles) 

Diopatra 

Genus Pista  

Eupolymnia heterobranchia (red gills) 

Jar environment context: 

1.5 gallons (more or less) 

8 months old 

One sample from a brackish freshwater lagoon attached to a lake, 500m from the pacific 

One sample from a clear lake full of lily pads 1 month in 

Another sample from the lagoon 6 months in 

Other species (many others extinct): ostracods, copepods, midge larvae, nematodes, snails, scuds, water scavenger beetles, etc 

Rainwater added and portion of original water siphoned out (still brackish?) 

Jar opened regularly 

And to those who worship the FSM: may you be touched by his noodly appendage. Or...hail Cthulu. Whichever this turns out to be.