A 'non-Cyclops' Copepod

NikonUser · Post by **NikonUser** » Wed Mar 16, 2011 9:07 am

The Copepoda (subclass of the Crustacea) has 4 freshwater groups with the short, stocky, Cyclops in the Order: Cyclopoida and some more elongated forms in the Order: Harpacticoida.
Collected this harpacticoid yesterday in a tiny stream that was flowing with snow-melt.
This is a female with a sperm package (spermatophore) on a long stalk that is attached by the male into the females's genital opening.
The blue/green colour is from a stain.

Top: 10x Nikon CF N Plan objective on bellows; reflected light.
Middle: 10x Oly SPlan Apo + 2.5x relay lens; transmitted light; 49 frames @ 4µ, ZS PMax; Nikon D90
Bottom: actual pixel selection showing spermatophore and 5th leg.

[ZS PMax is incredible software.]

NU11027 NU11028 NU11029

Charles Krebs · Post by **Charles Krebs** » Wed Mar 16, 2011 12:14 pm

NU,
Interesting subject. And very nicely photographed and presented!

Mitch640 · Post by **Mitch640** » Thu Mar 17, 2011 2:28 am

Excellent work. I am going to have to learn stacking, now that I have clean glass to take them with.

I have not seen this subclass in my tank yet. They are quite different, even to me.

NikonUser · Post by **NikonUser** » Thu Mar 17, 2011 5:43 am

Thanks Charles. These beasts apparently are rare in NB, a recent paper on the Subclass: Copepoda mentions only the Calanoid Copepoda and the Cyclopoid Copepoda.

Thanks Mitch. At first glance these resemble small Amphipods (shrimps), they swim 'smoothly' unlike the 'jerky' swimming of a Cyclops.
That complex structure of the 5th leg seems to be a defining feature for the harpacticoids.
Stacking is essential for any specimen that has depth; only problem is the specimen must not move. Otherwise, using ZS there is nothing to learn; just take a series of images and ZS PMax does the rest.

Mitch640 · Post by **Mitch640** » Thu Mar 17, 2011 6:00 am

One thing I have plenty of is Cyclops. The shrimp I got shots of the other day has gone back into the tank. He is hunting and eating Cyclops and has visibly gained size, just since the other day. I will watch for any suspicious looking 'pods.

Song miae · Post by **Song miae** » Thu Mar 17, 2011 7:25 am

I love these pictures !

Blue color is very beutiful and wonderful !
I thought that green color is green algae. But my mistakes !

NikonUser · Post by **NikonUser** » Fri Mar 18, 2011 5:07 am

Thank you, Song miae.
Many aquatic arthropods have a clear cuticle (exoskeleton), it is easier to see details when this cuticle is stained.

realjax · Post by **realjax** » Fri Mar 18, 2011 5:12 am

Lovely images! I know nothing about staining but would love to learn more, any idea where I can find more info?

Mitch640 · Post by **Mitch640** » Fri Mar 18, 2011 5:16 am

Jacco, being in Europe, you are in luck as far as buying dyes and stains. After a lot of searching about the subject here in the US, I found that all the good supply places are in the UK or Europe.

NikonUser · Post by **NikonUser** » Fri Mar 18, 2011 6:52 am

Arthropod cuticle is notoriously difficult to stain.

Acid Fuchsin and Chloral Black E are reputed to be excellent stains for arthropod cuticle. I am far from up-to-date for use of these. I'm sure if you Google "Staining Tecniques" you will find lots of information; there are books written on the subject.

Several stains have antibiotic properties and are used as disinfectants and such stains are taken up by cells.
The easiest source for these is a pet shop that sells tropical fish supplies.
Any chemical (with a colour) that is sold to kill fish parasites such as White-spot disease is worth trying. Old-fashioned chemicals were Methylene Blue, Methyl Green and Crystal Violet.

My local Wal Mart sells "Ick Guard"; the active ingredients being a blue dye (Victoria Green ?) and nitromersol. Dark blue stain that I used for the copepod. Simply soften the arthropod parts in 5% NaOH or 5% KOH overnight; thoroughly rinse with water to remove the alkali and then soak in a drop or two of stain until desired colour is obtained. If too dark (unlikely), a very weak alkaline soln (<1%) will remove excessive stain.

realjax · Post by **realjax** » Fri Mar 18, 2011 7:36 am

Thanks for the info. Not sure if I'm ready yet to stir up some alkali though.

But I'll check out my local pet shop!

NikonUser · Post by **NikonUser** » Fri Mar 18, 2011 8:00 am

Jacco,
I doubt if any stains will work unless you soften the cuticle. The wax layer on insect cuticle will likely resist the penetration of any stain. Aquatic arthropods may be easier to stain.

NaOH is a dangerous chemical. It is sold over here in pellet form for opening blocked toilets. One pellet in about 50 mL of water is reasonably safe to handle and should work. Low cons. work better (and slower) than higher cons. So, perhaps work with a very weak soln. and let the arthropod soak for 1-2 days (trial and error process).