Jump to content

New Library Article - Odonata Anisoptera - Dragonfly Nymph


NoGi

Recommended Posts

14755165667_648c9bf15e_b.jpgDragonflies or Odonata Anisoptera, are a group of insects belonging to Class Insecta, Order Odonata and Suborder Anisoptera. Considered as ancient, their ancestors were around during the Jurassic Period, along with the dinosaurs. They are predators. Their life cycle breaks down into three distinct stages: the larval stage, the nymph stage and the adult stage. Nymphs can spend a number of years living in fresh water. The adults, which may only last a few days or weeks, can fly. Adults emerge to mate and repeat the dragonfly life cycle. The body length of the average adult dragonfly can vary between 2.54 cm to 10.16 cm. Ancient dragon flies could have a wingspan as large as 70 to 75 cm in extent. The juvenile, dragonfly nymph can range in size between 1.27 cm and 3.81 cm.

The dragonfly nymph is a formidable predator. It spends its life just below the water surface, and has a “hinged labium, a form of a “toothed” lower jaw. It can extend this out every quickly then retract it. This way, the juvenile dragonfly can catch and eat tadpoles, mosquito larvae and even small fish.

Does the dragonfly nymph pose a threat to fish and shrimps in an aquarium? The short answer is definitely yes. There may be as many as 1500 eggs originally hatched. Having come down to us from the Jurassic period, the Odonata Anisoptera juvenile is equipped with the equivalent of a “rapture like lower jaw”. They would have no problems consuming both small fish and shrimps in an aquarium. Bringing fresh water from natural sources may sound a good idea, but there could be a good chance that this could be contaminated with the dragonfly nymph.

Another indication would be that both the small shrimps and fish are showing signs of stress. They are aware that there are dragonfly nymphs in there with them. Removing Odonata Anisoptera may not be that easy once the aquarium is infested with them.

One method could be to use a plastic straw to suck the juveniles out individually. Plants and other water vegetation need to be agitated to get them to move, as the dragonfly nymph can remain very still. Dropping the water temperature in the aquarium by three to five degrees Celsius, might stress shrimps in the tank. This might also bring the dragonfly nymph to the surface.

References

https://en.wikipedia.org/wiki/Dragonfly

https://en.wikipedia.org/wiki/List_of_Odonata_species_of_Australia

http://www.state.ky.us/nrepc/water/dragfly.htm 

14755165667_648c9bf15e_b.jpgPhoto Credit: dmills727 Flickr cc

16509784424_a586b1cf00_b.jpgPhoto Credit: Exmoor National Park Flickr cc


View full article

Link to comment
Share on other sites

  • 1 month later...

I had some of these in my Cherry Red Shrimp tank.

They hitched a ride on some driftwood I got from a local lake.

They looked pretty cool and I didn't notice them stressing my shrimp too much though they must have been predating upon them.  I saw one of my adult shrimp actually sitting on top of one of these nymphs.

I haven't seen them for a few weeks, so I'm thinking they may have died off. 

 

  • Like 1
Link to comment
Share on other sites

24 minutes ago, Moksha said:

I'm thinking they may have died off. 

I highly doubt it. Keep an eye out for them. They might just be hiding away evolving into the next larvae phase where their abdomen grows longer. They can moult up to 12 times, growing bigger after each moult.

I'm just going to leave this vid here, as to why we would want to make sure our tanks are clear of these predators....

 

Edited by jayc
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Join Our Community!

    Register today, ask questions and share your shrimp and fish tank experiences with us!

  • Must Read SKF Articles

  • Posts

    • beanbag
      Update to say that after a few gravel vacs, front wall scrub, moss / floating plant trim, that the condition seems to have improved.  My current theory is that it is due to waste / debris management, where "stuff" like that brown mulm accumulates in the substrate and behind the HMF filters.  Maybe some tanks can somehow deal with it, but mine can't.  Also another experienced shrimper suggested that maybe those "shell bugs" don't just live on the shrimps but also in this debris.  Maybe this is the reason some tanks fail due to "old tank syndrome" where all they need is a good gravel vac? Also, I am guessing that plant trim helps too because now more of the nutrients and light go into growing algae instead of more plants? Well anyway for this tank I will try weekly water change and monthly gravel vac / plant trim.  For my next tank, I'm thinking of something like an under-gravel system where this mulm can fall down and I vac it out.
    • sdlTBfanUK
      Good to have an update and good to hear you are getting shrimplets, so hopefully your colony will continue and you may not get to the point where you have to cull some to stop over population. These type of shrimp only live 12 - 18 months so the adult deaths may be natural? If you have the time I would do weekly 25% water changes, adding the new water via a drip system and do some vacuuming clean of the substrate each week, even if only a different bit each week! See if that helps in a few months and if it does then stick with that regime? It should help reduce any build-ups that may be occuring!
    • beanbag
      Hello again, much belated update: The tank still has "cycles" of 1-2 month "good streaks" where everybody seems to be doing well, and then a bad streak where the short antenna problem shows up again, and a shrimp dies once every few days.  I am not sure what causes things to go bad, but usually over the course of a few days I will start to see more shrimp quietly standing on the HMF filter, and so I know something is wrong.  Since I am not "doing anything" besides the regular 1-2 week water changes, I just assume that something bad is building up.  Here's a list of things that I've tried that are supposed to be "can't hurt" but didn't prevent the problem either: Dose every other day with Shrimp Fit (very small dose, and the shrimp seem to like it) Sotching Oxydator Seachem Purigen to keep the nitrates lower Keeping the pH below 5.5 with peat Things that I don't do often, so could possibly "reset" the tank back to a good streak, are gravel vac and plant trim, so maybe time to try those again. One other problem I used to have was that sometimes a shrimp would suddenly stop eating with a full or partially full digestive tract that doesn't clear out, and then the shrimp will die within a few days.  I suspected it was one of the foods in my rotation - Shrimp Nature Infection, which contains a bunch of herbal plant things.  I've had this in my food rotation for a few years now and generally didn't seem to cause problems, but I removed it from the rotation anyway.  I don't have a lot of adult Golden Bees at this point so I can't really tell if it worked or not. Overall the tank is not too bad - during the good streaks occasionally a shrimp will get berried and hatch babies with a 33-50% survival rate.  So while there are fewer adults now, there are also a bunch of babies roaming around.  I guess this tank will stagger on, but I really do need to take the time to start up a new tank.  (or figure out the problem)
    • jayc
      If that is the offspring, then the parents are unlikely to be PRL. I tend to agree with you. There are very few PRLs in Australia. And any that claim to be needs to show proof. PRL genes have to start as PRL. CRS that breed true after x generations doesn't turn it into a PRL. Neither can a Taiwan bee shrimp turn into a PRL despite how ever many generations. I've never seen a PRL with that sort of red colour. I have on Red Wines and Red Shadows - Taiwan bee shrimps. So somewhere down the line one of your shrimp might have been mixed with Taiwan bees and is no longer PRL. It just tanks one shrimp to mess up the genes of a whole colony. 
    • sdlTBfanUK
      Sorry, missed this one somehow! The PRL look fantastic and the odd ones look part PRL and part Red wine/Red shadow in the colour. They are still very beautiful but ideally should be seperated to help keep the PRL clean if you can do that.  Nice clear photos!
×
×
  • Create New...