Translucent blobs - ID please? (pic)

mleinart · #1 08/07/2006, 05:08 AM

I have a newly established tank, about 3 months old. In addition to several types of cleaners and a few fish, I've added live sand from a few different sources (Inland Aquatics, Bill's Reef, GARF) and two 'pod kits (Inland Aquatics, Indo Pacific Sea Farms).

A week or two ago, I noticed these weird blob things in the bottom of my refugium (about 2 weeks after adding sand from GARF). They're translucent, slightly sticky (they stick to sand, macroalgae, life rock), and have two (usually open) tubes coming out at ~90deg angle from each other. They pulse about once a minute, and I can kindof see the insides - looks like things you'd seen in a eukaryotic cell diagram from biology class. I think I may have once seen an amphipod scurry out of one of the tubes, but I can't be sure that it wasn't just running on the surface.

Can anyone identify these things? I've never seen any pictures of anything that look like these.

Here are three of them (out of maybe 4-5 I've spotted total):

Thanks!

Chupakabra-King · #2 08/07/2006, 09:21 AM

They might be some sort of jellyfish polyp . ..

LeslieH · #3 08/07/2006, 09:54 PM

They're tunicates. The two openings are the incurrent and excurrent siphons. You can sorta see some of the internal structure through the body wall. These are filter feeders and excellent if you have lots of particulates in your water.

Chupakabra-King · #4 08/08/2006, 07:39 AM

They do look like tunicates but I have never seen a tunicate pulse before . Weird !

LeslieH · #5 08/08/2006, 04:42 PM

The pulsing is done to expel unwanted particulates. It's probably more noticeable with solitary forms & ones like this with soft bodies.

Chupakabra-King · #6 08/09/2006, 07:40 AM

Very interesting !

You learn something new every day !

Thanks !

mleinart · #7 08/11/2006, 06:45 PM

Oh cool. I was hoping they were some type of sea squirt, but it didn't look like they had a 'tunic' (I guess these have a translucent tunic rather than the leathery ones I've heard described?). Since I posted these pictures a few more have popped up, some appear to be a different type with a dozen or so different length and diameter tubes coming out radially from the base. Really neat.

Does anyone know whether these have a flow preference? I'm thinking about moving a few of these to another part of my sump before the skimmer where they'll get more flow and maybe slightly more nutrient rich water.