Has your hydroid been ID'd as a digitate hydroid?

[Lionfish Lair]

What IS a Digitate Hydroid?

I'm going through all the hitchhiker critters and fact checking etc for the new guide. So, I hit Digitate Hydroids, and what did I find.... Nadda, Zippo, Big ole goose egg. The only place this shizzle shows up is in our forums and sites about the hobby.

Google Search

If y'all find information that was not written by someone or for someone in the hobby, could you let me know. If I ID'd your hydroid as a Digitate, I apologize and "take it back". LOL! I was wrong and there's egg on my face. There's more to it than that.

 

[erk]

I've never seen any hydroids in my tank, but I definitely enjoy helping with research on the random animals that inhabit our tanks. What I could find is that the genus Obelia seems to encompass what is called a digitate hydroid which appears to be just a type of colonial hydroid. From the Wikipedia page, these are very common in intertidal regions down to 200m.

http://cronodon.com/BioTech/Obelia.html
https://en.wikipedia.org/wiki/Obelia

 

[twilliard]

Haha the good old digitate hydroid.


And an awesome cure..
Fenbendazole

 

[Lionfish Lair]

Are they specially referring to the hydroids as Digitates in those references @erk ?

 

[erk]

Are they specially referring to the hydroids as Digitates in those references?

No. I'm going off the growth pattern rather than wording. When you search digitate, it comes up only with reef forum posts. But the method by which the colony grows in a perpendicular direction from its attachment point with heads branching off in an alternating pattern seems to be a major form of the Obelia genus of hydroids. Also, their very large distribution makes me believe they would be a more likely candidate than something more unique.

 

[Lionfish Lair]

There's a specific type of hydroid that the hobby has been referring to as digitates.... it's the one above Twill posted. To me, that doesn't appear to be a Obelia.

If digitate is the common name this hobby chose to label these hydroids, it's all well and good, but with every other critter, there is a scientific connection so one can go and look for information outside of this hobby.

 

[twilliard]

I have searched far for a species name with no true conclusion.

 

[Lionfish Lair]

Right? It's actually kind of odd. Take any other critter in my guide and you won't find that. Mine was ID'd for me years ago and I just sort of ran with that. But it's got to have a loose scientific ID of some sort, to at least tell us some things about it..... from people NOT connected to the hobby.

 

[erk]

There's a specific type of hydroid that the hobby has been referring to as digitates.... it's the one above Twill posted. To me, that doesn't appear to be a Obelia.

If digitate is the common name this hobby chose to label these hydroids, it's all well and good, but with every other critter, there is a scientific connection so one can go and look for information outside of this hobby.

It would be nice if we had a microscopic view of a digitate hydroid. But what do you think of figure A on page 61 of the linked pdf?

https://repository.si.edu/bitstream...ki_et_al._2013_MPE.pdf?sequence=1&isAllowed=y

Figure A is aculis ilonae. Issue is that it is found in the Antartic region.

Sarsia bella is also from cold waters.

http://www.racerocks.ca/hydroid-photomicrography-by-dr-anita-brinckmann-voss/

Edit: Could always submit the picture Twillard posted to Dr. Anita Brinckmann Voss?

 

[Wiz]

I have these guys in my system. Mainly in my refugium. They don't seem to bother anything. Very interesting that the name is wrong. Now I feel like I must search. LOL

 

[Lionfish Lair]

This is also a nice reference to hydroids.

https://faculty.washington.edu/cemills/LSM2007Cnidaria.pdf

I somehow deleted myself with mentioning the sarsia.... (I ALWAYS accidently delete my stuff when I edit...grrr). I don't think it IS one, but it has the same feeding behaviour as the things in our tanks. So, I take that, and climb around the taxonomy tree until I trip on more info and so on....

There are a few things that show up in our tanks that are typically found in coldwater, though, so that doesn't so much bother me.

There's a book I'd also like to get my hands on. You can see some of the images that are IN the book in a google search, but can't view them directly.

https://www.google.com/search?q=Gym...KlIKHVgiDO04ChD8BQgGKAE#imgrc=Oxet-Q5LxDRdkM:

 

[Lionfish Lair]

This is the one about sarsia.

 

[Lionfish Lair]

I just contacted Dr. Anita Brinckmann Voss. Thanks for the name @erk

 

[erk]

Here is a pdf I found on Sarsia producta.

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&ved=0ahUKEwjTzt7G-5vNAhWDy4MKHbr7BpQQ5TUICQ&url=http://www.vliz.be/imisdocs/publications/31823.pdf&bvm=bv.124088155,d.aXo&psig=AFQjCNFveYC8ze4bOVsYM8lieW-Z54j7yg&ust=1465596722525220&cad=rjt

I definitely see how a Sarsia species fits the bill. From your link, Coryne species seem a decent fit as well.

Edit: Lol, we found the same Sarsia document.

 

[erk]

I think when people observe small jellyfish type animals in their tanks, these are the free swimming stage of hydroids.

 

[Lionfish Lair]

Yes, that's the same write up I attached above. We're probably not going to be able to ID down that specifically, because there are a few that look similar. I don't care if we can pinpoint it, as long as it's a legit label, you know what I mean?

I like that repository link.

 

[Lionfish Lair]

I think when people observe small jellyfish type animals in their tanks, these are the free swimming stage of hydroids.

Oh absolutely. I agree 100%.

 

[erk]

Yes, that's the same write up I attached above. We're probably not going to be able to ID down that specifically, because there are a few that look similar. I don't care if we can pinpoint it, as long as it's a legit label, you know what I mean?

Totally agree. From the pictures I've seen on the web of digitate hydroids, they encompass more than one species. Some pictures which I think are mistakenly called digitate hydroids look like a total different genus like Obelia.

 

[Lionfish Lair]

Well, it would be nice if it had a name that began with a D so it won't mess with my alphabetical order.... so work on that for me, would ya? D names only

 

[Lionfish Lair]

Zanclea