OK, Next Fish

[SeaYoda]

This guy was in <10' of salt water near the shore here in Destin Florida. He had 3 grey snapper friends but he was smaller (about 1/3 the size of his buddies). Is this just a juvenile or some other snapper? Below the shot of him (the yellow guy) are two pictures of his companions.

 

[maractwin]

I'd guess it's a schoolmaster. A late juvenile transitioning to adult coloration.

-Mark

 

[TwoBitTxn]

The bottom two are gray snappers. I think the top is too, just a different color phase.

TwoBit

 

[Walter]

They all look like Mangrove Snapper to me.

 

[archman]

The bottom two are gray snapper all right, what floridians typically refer to as mangrove snapper. The black eyeband is characteristic for different sub-populations. Not all of them have them.

Top one's a juvenile schoolmaster. Schoolmaster's have all-yellow fins, and the juvies bear that distinctive eyeband. They lose it at adulthood.

When pickled, they all look alike. Boo!

 

[SeaYoda]

What is the politically correct and safety conscious fluid for pickling specimens these days? We always had the good old carcinogen, formaldehyde.

 

[archman]

What is the politically correct and safety conscious fluid for pickling specimens these days? We always had the good old carcinogen, formaldehyde.

Well formaldehyde is a gas. Formalin is the liquid derivative used for preservation. Most science folks use a 3% mix for pickling, which is nasty enough. The fumes at 10% are near-unbearable. A lot of people improperly dilute to 10%.

Due to wussy complaints, formalin is mostly phased out of educational use. Most of the truly effective preservative agents (i.e. xylene) are politically incorrect nowadays. I think even glutareldehyde is frowned upon.

There's this stuff called carosafe that's the rage now. It sucks.

75% or 95% ethanol still works just fine. It dries your hands out, of course. Ethanol is the preferred method for long term storage of most animals, and has been since the 19th century. Formalin's a LOT cheaper, however. Formalin also has the advantage of retaining colour in animals longer than if they were in ethanol.

Hardcore zoologists narcotize or "fix" animals first in 3% formalin, and then replace with ethanol. Formalin is much less traumatic at killing, and gives you a better quality specimen. Long term formalin-preserved specimens should be buffered, as straight-up formalin is slightly acidic. This is particularly bad for critters like shells, clams, and echinoderms. Formalin's also A-1 at destroying DNA, whereas ethanol is much nicer.

In a pinch, vodka or tequila work well too. In remote areas, a lot of field stations use this method for the bulk of their preservation.

 

[SeaYoda]

We still use formalin in the pathology lab for histology specimens. It's high on the safety watch list. I don't work in the histology / cytology end of the lab so I'm always playing in fresh body fluids. Nothing pickled for me .

I still have a vivid memory of the smell of earth worms preserved in ethanol from high school - I think I like the formalin better, although we probably breathed too much of the fumes from those 55 gallon drums of kittys, pigs, and sharks.

 

[WVDiver]

Well formaldehyde is a gas. Formalin is the liquid derivative used for preservation. Most science folks use a 3% mix for pickling, which is nasty enough. The fumes at 10% are near-unbearable. A lot of people improperly dilute to 10%.

Due to wussy complaints, formalin is mostly phased out of educational use. Most of the truly effective preservative agents (i.e. xylene) are politically incorrect nowadays. I think even glutareldehyde is frowned upon.

There's this stuff called carosafe that's the rage now. It sucks.

75% or 95% ethanol still works just fine. It dries your hands out, of course. Ethanol is the preferred method for long term storage of most animals, and has been since the 19th century. Formalin's a LOT cheaper, however. Formalin also has the advantage of retaining colour in animals longer than if they were in ethanol.

Hardcore zoologists narcotize or "fix" animals first in 3% formalin, and then replace with ethanol. Formalin is much less traumatic at killing, and gives you a better quality specimen. Long term formalin-preserved specimens should be buffered, as straight-up formalin is slightly acidic. This is particularly bad for critters like shells, clams, and echinoderms. Formalin's also A-1 at destroying DNA, whereas ethanol is much nicer.

Very good write up.

In a pinch, vodka or tequila work well too. In remote areas, a lot of field stations use this method for the bulk of their preservation.

In W.V. we use moonshine to pickle............ cheap and homemade.

 

[archman]

We still use formalin in the pathology lab for histology specimens. It's high on the safety watch list.

Formalin's good for cell-sized thingies, as it doesn't distort the cells like ethanol. Ethanol sucks all the water out, violently. Formalin, on the other hand, is mostly just plain old water with a smidgeon of the nasty.