Mystery Hydroid

GaleB · Sep 27, 2022

I observed this critter in one of my store tanks for about two months. I have unfortunately moved and never managed to get better photography so I'm afraid this will have to do. I'm just fascinated by them because I have not been able to ID them for months! I have collected a couple other posts that contain pictures of something that looks similar— so far, positive ID has not been offered in any of those threads. They seem pretty rare compared to digitate and medusa hydroids. Whats unique about this animal is that each polyp has a holdfast, as opposed to other branching hydroids which have colonies that extend out into the water. Perhaps this body format is an early stage of those other hydroids? Flow too high to risk forming an appendage?
I'm starting to worry that this species has only been observed in the hobby and hasn't been named because we are all too concerned with killing it! I have been sharing with my biologist/aquarium friends and none of them have seen anything like it.

If you have had these guys or ever attempted a similar ID I'd love to hear about it.

Looks like it might be my guy:

Hydroids?

from what I gathered from other posts around it here it seems like these are hydroids, but I couldn't find much more information other than the fleshy white type of hydroids seem to go away on their own. If anyone knows the proper name or has more information I'd really appreciate it. I'm not...

www.reef2reef.com

Potential hydroids taking over

What was supposed to be a ‘clean’ tank building pod population has exploded with what appears to be a couple different types of hydroids. Can someone confirm? Any potential predators to knock them back? Options? The rock is picking up steam with what appears to be the same minus the...

www.reef2reef.com

HydrozoanFAQs

Kinda like my guy but with detached polyps:

Branching or Colonial hydroids?

Trying to confirm if these are colonial hydroid (Obelia longissima or Obelia dichotoma) or something else also is it safe to pluck away? That's what I been doing but have heard mix reviewed due to they being asexual. Lastly anyone knows a natural predator? I read some types of hydroid sting to...

www.reef2reef.com

Hydroid ID

What type of hydroid is this? They are everywhere in my tank and bothering my zoa's.

www.reef2reef.com

vetteguy53081 · Sep 27, 2022

GaleB said:
I observed this critter in one of my store tanks for about two months. I have unfortunately moved and never managed to get better photography so I'm afraid this will have to do. I'm just fascinated by them because I have not been able to ID them for months! I have collected a couple other posts that contain pictures of something that looks similar— so far, positive ID has not been offered in any of those threads. They seem pretty rare compared to digitate and medusa hydroids. Whats unique about this animal is that each polyp has a holdfast, as opposed to other branching hydroids which have colonies that extend out into the water. Perhaps this body format is an early stage of those other hydroids? Flow too high to risk forming an appendage?
I'm starting to worry that this species has only been observed in the hobby and hasn't been named because we are all too concerned with killing it! I have been sharing with my biologist/aquarium friends and none of them have seen anything like it.

If you have had these guys or ever attempted a similar ID I'd love to hear about it.

Looks like it might be my guy:

Hydroids?

from what I gathered from other posts around it here it seems like these are hydroids, but I couldn't find much more information other than the fleshy white type of hydroids seem to go away on their own. If anyone knows the proper name or has more information I'd really appreciate it. I'm not...

www.reef2reef.com

Potential hydroids taking over

What was supposed to be a ‘clean’ tank building pod population has exploded with what appears to be a couple different types of hydroids. Can someone confirm? Any potential predators to knock them back? Options? The rock is picking up steam with what appears to be the same minus the...

www.reef2reef.com

HydrozoanFAQs

Kinda like my guy but with detached polyps:

Branching or Colonial hydroids?

Trying to confirm if these are colonial hydroid (Obelia longissima or Obelia dichotoma) or something else also is it safe to pluck away? That's what I been doing but have heard mix reviewed due to they being asexual. Lastly anyone knows a natural predator? I read some types of hydroid sting to...

www.reef2reef.com

Hydroid ID

What type of hydroid is this? They are everywhere in my tank and bothering my zoa's.

www.reef2reef.com

Colonial hydroids and hydrazoa

ISpeakForTheSeas · Sep 28, 2022

The fact that it's only growing polyps on side of the branch (i.e. all of the polyps seem to be growing upwards in the photo) is interesting to me, as all of the similar specimens that I know have polyps growing on both sides of the branch (top and bottom). I don't know if that's because it's a young specimen in your photos or if it just grows like that regardless of age, but it's definitely interesting.

That said, here are some similar specimens that - if nothing else - might give you a place to really start you search for the species:
- Eudendrium (genus) [this one would be my guess, but I'm definitely not a hydroid expert]
- Bougainvillia (genus)
- Turritopsis (genus) [a few of these look similar, most of them don't]

Alternatively, you might be able to reach out to a hydroid special (like Joan J. Soto-Angel, who you can find on Twitter and Instagram) and see if they could help you ID it. Sometimes professionals are open to helping, sometimes they're not. I've found it helps if you remain respectful/professional with them but also let them know you're genuinely interested in/excited by the topic you're asking them about (but it's still not guaranteed that they'll help/get back to you).

Good luck on your search, and welcome to Reef2Reef!

GaleB · Sep 29, 2022

ISpeakForTheSeas said:
The fact that it's only growing polyps on side of the branch (i.e. all of the polyps seem to be growing upwards in the photo) is interesting to me, as all of the similar specimens that I know have polyps growing on both sides of the branch (top and bottom). I don't know if that's because it's a young specimen in your photos or if it just grows like that regardless of age, but it's definitely interesting.

That said, here are some similar specimens that - if nothing else - might give you a place to really start you search for the species:
- Eudendrium (genus) [this one would be my guess, but I'm definitely not a hydroid expert]
- Bougainvillia (genus)
- Turritopsis (genus) [a few of these look similar, most of them don't]

Alternatively, you might be able to reach out to a hydroid special (like Joan J. Soto-Angel, who you can find on Twitter and Instagram) and see if they could help you ID it. Sometimes professionals are open to helping, sometimes they're not. I've found it helps if you remain respectful/professional with them but also let them know you're genuinely interested in/excited by the topic you're asking them about (but it's still not guaranteed that they'll help/get back to you).

Good luck on your search, and welcome to Reef2Reef!

Thank you SO MUCH, you rock!!! I will update this thread with any findings.