Stingray Dissection *Warning Graphic Images

Dieselhybrid

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*Please note there are very graphic images in this thread. Leave now if you are uncomfortable *

"Learn from your mistakes"

That was the name of a recent thread created by MFK guru Oddball. The thread showed a bichir that had died, and an autopsy he had performed in which he identified the organs. I was thankful he shared his experience and understood the value of it. Speaking of Oddball if you want to learn and expand your overall knowledge base search and read the 100's maybe 1000's of threads he's contributed over the past, well, decades. Endless information, take advantage that guy is an encyclopedia. I've learned more from him than possibly any other source. Big thanks to him

"Take the good with the bad"

Two days ago we had 4 pups (yay! thread on them coming soon!).
The next day we lost a hybrid female (not the mother, different tank). The hobby has ups and downs. Eventually, we experience losses. The only variable on this, is time. I feel obligated to share our failures and defeats along with our proudest moments. Can't just share new acquisitions and pretty babies, without being realistic and admitting bad things have happened along the way. If you've experienced losses you understand. If you haven't experience losses then listen. Don't give up or lose focus, you owe it to the remaining stock to learn from it and to keep improving.


Ok on to the topic at hand. This is a 5 year old female stingray of the Potamotrygon genus, of unknown hybrid species (Could speculate all day but hey...thailand...pointless to guess her DNA). The decision was made to dissect her body for several reasons:

1. Identify cause of death
2. Determine if cause of death presents a continued threat to surviving stock
2. Determine if there are any anatomical abnormalities
3. Learn more about stingray anatomy, develop a better understanding
4. Not let her die in vain (in the same sense that I am an organ donor when my grumpy ass finally dies)

Again, please note there are very graphic images in this thread. I'll share all of the background information and details/observations that I can without being too long winded. Questions? Ask them. If you're the Woozy type then click the back button on your browser. Or get a puke bucket.. or somebody get me some tissues... :( For those of use who can stomach it, maybe we learn something. I found a dissection guide online, was pretty darn handy. I will include the guide. Big thank you to SHARK13 SHARK13 for sharing photos and details of a loss he suffered, that helped greatly in preparation. Feel free to contribute or correct any mistake I make along the way here. I'm not a defensive person, so share suggestions if you like. This is my first fish dissection, and I was personally attached to the deceased adding a degree of difficultly. Also adding to the difficultly was the fact that my partner cannot stomach this and with her returning soon, I had to get started before I completely realized what happened

The deceased was found in the morning around 8am. working backward in time. She was last seen alive and active at 11pm the night before. She refused food at her last evening feeding around 8pm behavior otherwise normal. No heavy breathing and active. She ate a moderate amount at her feeding that morning around 8am. All days previous to this behavior completely normal. The reduction of food was noticed one meal, she refused the next, and was deceased the next. Sad as she was a beautiful creature.

There are multiple male stingrays in the tank. They are all active breeder size. they have shown breeding activity to many females but never this female. This female is the alpha female in terms of aggression. She has a more "male" disposition in terms of dominance, food aggression, and biting nature. She has had one food strike in the 4 years of ownership that lasted 4 days, cause unknown, several years ago.

Suspected possible causes of death no particular order:

-Fatal barb sting
-Choked on shed barb
-Internal infection
-Possible intestinal or digestive tract blockage
-Stress related sudden instant death
-Genetic hybrid defect (read an article on this and never bookmarked it, I'll find again some day)
-Water quality (tests look flawless)
-Unknown causes (much I could be overlooking)

I'll walk through and add info and pictures as we go. I included screenshots of the guide as there wasn't a way to attach PDF. Dissection guide is here to find the origin: http://www.steinbachscience.com/l&o/resources_marine_bio/MB_Ch8/MixedFishesDissection/SkateGuide.pdf

Her tail was wrapped and taped immediately after removal from the aquarium. protective gloves were worn to prevent transfer of mucus to skin and cuts from denticles. Denticles are tiny bumps all over rays discs. Some rays have more of these than others. Some can be elongated and sharp, they can potentially cut you. Protect yourself when handling a dead ray. It can still sting and cause a world of hurt. Resist the tendency to let your guard down simply because it's deceased. Safety first.

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Dieselhybrid

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This is a pretty small ray things considered. She's 5. Maybe even 6 years old now and only has 15" disc. Never bred. Only passed 12" in size last year (recent growth spurt maybe a clue). Not a huge eater until the growth spurt. Grew painfully slow as a pup.

referring to the dissection guide helps

The kitchen cooking scale was tested for calibration as it never gets used. A US nickel (.05 cent piece) weighs 5 grams for those of you who didn't know. So the scale is accurate at least when weighing next to nothing in weight. For what that's worth. We are using grams as units of measure because well, metric is just better than imperial....Ok geez I'll try to include the conversions...innumerate...

3843 grams. That's her total body weight. The box her body is placed on was "tared" or zeroed out on the scale before her body was added to try and give the most accurate weight possible. OK....there's 453 grams in a pound (come on! that's close enough) sooo that means 3843 divided by 453 = 8.48344 yeah we'll just call it 8.5lbs :)

Her on the scale, yes she was a Seahawks fan just a like all fresh and saltwater stingrays in fact. This was just recently discovered as it is actually programmed naturally in their DNA.

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Dieselhybrid

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These types of tape measurer pictures are always deceiving holding it elevated with the convex fish shape. 15" That's my answer and I'm sticking with it

Awww wasn't she pretty? She shows no posterior injury or damage, I cannot find a barb puncture wound top or bottom. Which would be difficult to spot on her dark base or in the white of a spot but I looked long and hard with a 700 lumen flashlight and couldn't find any puncture wounds anywhere on her body. Eyes look healthy and in tact, spiracles unobstructed, let's flip her over belly up.

The anterior (belly)bottom tells a story. Redness all over, especially noticeable around the gills. SHARK13 SHARK13 noticed this too during his dissection. What I don't know is if this is common after the death of all stingrays? Or if this is a clue as to cause of death? I don't know if this is typical? Anyone who has lost a ray have you seen redness like this on the belly? Maybe this is a clue of sepsis and internal infection.

Her mucus left on the towel was such a neat pattern...

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Dieselhybrid

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Water samples were collected and tested as soon as the deceased was noticed. Nothing helpful there with the standard ammonia, nitrite, nitrate test. Everything looks perfect. Did an emergency 80% water change anyway and dosed with nitrofurazone just in case there is something funky lurking in that system. The tank gets regular large changes and is on a heavy drip so the idea of a free floating infection sounds unlikely but anything is possible.

You know you've been doing this a long time when you don't need the color reference card to compare colors to anymore with the api kit. :)

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Dieselhybrid

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I have more hours using a filet knife than any other knife, so that was my tool of choice here. I tried to cut around the pleuroperitoneal (body) cavity with shallow cuts. you can feel the cartilage around the cavity. I then removed the abdominal muscle tissue and skin opening the cavity so we could see inside. This is around step 10-11 on the guide for those following along :)

The first thing I noticed was the liver. The sheer enormity of it. Nothing is visible inside of the cavity because the liver is that large and covers the entire anterior portion. The liver has what appears to be 3 lobes which is consistent with the guide. It's uniform in texture and color, cream colored without any visible abnormalities. Between the right and median lobes lies the gall bladder. One thing I noticed was that the body cavity was relatively dry. meaning it wasn't filled with blood, or green bile. Bile was present in comparatively small amounts to many other dissections which have a body cavity filled with bile and/or blood. In other specimens this could be a cause or symptom of what caused death. It must also be considered that the filled body cavities in those scenarios were due to tissue puncture during dissection. I was fortunate enough to avoid puncturing the liver and gall bladder during dissection. Because of the obstructed view beneath the liver it was removed to better view the rest of the body cavity

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Dieselhybrid

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The liver weighed in at 314 grams including the attached gall bladder. You can see the gall bladder tucked between the right and median lobes, has a slight greenish color inside. You can see the membrane is still in tact containing the green bile.

Wait?!?!? 314 gram liver!? That's almost 3/4 of a pound. In a creature that weighs 3843 grams. Her liver comprised about 8% of her body weight. Perhaps that's normal? I wanted to record this so the next poor soul who does this has a reference (and when it's inevitably my turn again) so we can start compiling some data. I would be interested to see liver/body weight comparisons. I would estimate that the liver occupies 2/3 of the volume of the body cavity.

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Dieselhybrid

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Sad to see it was a stunning ray.

That towel print is pretty interesting. I wonder if it would dry and make a death print of the ray. I would love to frame the pattern of my rays if I lose one.
That is a fantastic idea!! The towel was discarded because...well ewww. Hopefully this never happens again. Back to reality. When this happens again I will use a linen or screen-cloth of some sort and take a screen print. It appears the mucus absorbs pigment, likely from shed skin cells below the mucus.

Tons of mucus. I didn't mention that yet, but these are ultra slimey and thick slime coat that you simply can't wipe off or completely absorb. It's possible they continuously secrete mucus after death. Wear gloves for sure, and don't scratch your eyes!! or your nose!! or your....
 

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Dieselhybrid

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This is where it gets a little bit uncertain for me, so I'll explain as I have interpreted which I believe is correct but obviously could not be. I'm also going to try and make sure the photos present in a certain order to trace the path of the digestive tract. We are around #12-14 guide.

The pharynx is the throat from the back of the mouth, down behind the gills. You can see the gills in the upper right of the photo. The pharnyx then attaches to the esophagus which you can see being pointed to. The guide mentions that the esophagus is lined with papillae (small rounded protuberances and grooves) that help food travel to the stomach. Unfortunately the photo of the interior of the esophagus is mostly focused on the fingers. Don't worry the cameraman has been fired and shall not receive a reference for this shoddy work. (We will also examine the upper digestive tract later)

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