Ok hope you don't mind some more constructive criticism from a fellow Radiographer. I did study X rays then subspecialized in Nuclear MEd and left hospital to work in application training since 3 years... (so do I get to criticize???)
Your pics are good but can be improved a bit:
-Pic 1 from top
a Bit soft could use some sharpening, would have love to see the beginning of the branch. the blurred branch next to it (although it is there) does nothing in the picture and appears severly clipped. Maybe be clone it out. a tiny bit overexposed.
-2
Unless zooming on a few coralites I'd rather have the whole branch inthe picture. abit soft and more overexposed. it's a tough pic to meter as you get a wide dynamic range from green to white.
-3
Even if centered composition works. would have been better if you shifted it a bit to the left so it's not in the center and then you could have avoided that small brang that is doing nothing to the picture. the branch would have moved then from the left lower corner to the middle of the pidture which is not considered a dead centered pic.
Also overexposed. also a bit soft.
-4 the blurred small branch takes away from the picture. all branches are cut from below and overexposed. A vertical shot could have worked better.
Although not really soft it's not crisp sharp. Would have loved to see a shallower DOF with some of the polyps in crisp focus as that would lead the eye to polyps which are the main character in a coral just like eyes.
2nd batch
-1 you just did what I ws recommending on last pic and it's much better. A shallower DOF would have even been better if you could keep the polyps crisp but the shot is great. Starting this shot your most of your shots are sharper so what happened? are you using faster shuitter speeds or supporting the camera as the sharpness is evident.
-2 and 3
a bit soft and overexposed.
-4
Would have loved to see at least one single polyp which is not cut and it should be the one where you focus. and maybe slightly less FOV
-5
Better pic but you focused on the polyp in the middle but rather metered on the one on its left so the one in the middle is in focus but a tad dark and the one on the left properly exposed or maybe on the upper edge of properly exposed. I love how clear this pic is.
-6 would have loved a more crisp polyp with less DOF for others.
How are you supprting your camera and are you shooting at an angle to glass as those could cause some distortion.
3rd batch
-1
nice picture but still the main polyp which is in focus is not properly lit the shadow in the polyp above the mouth is disturbing.
-2
would be great if it was crispier
-3
nice pic would be perfect if it was a tiny bit less exposed as you'r clipping the upper tip.
- 4 & 5
noisy. is it high Iso or corrected darke shots. increasing exposure can introduce noise so it's critical to expose proerly in camera.
-6
love this choice but would recommend a sharpening filter for it.
7- nice shot exposure is tough with the wide Dynamic range. would have loved to have it a bit darker and much sharper.
-8
This shot makes me dizzy. you could have made better use of the lines in this coral using them as guiding line going in or out twoards a sharp polyps with a blurred surrownding. but I see no real focus area or any sharpness on few polyps to show that this is the center of interest in this image.
One last pick. Maybe give number to your pictures which makes it easy to relate which one got which critique. Overall you just need to improve your technique in getting sharper images:
-better focus
-stable camera or maybe use flash (moderate to avoid clipping highlights more)
artistic side:
better use of DOF and metering to guid the eyes of the looker to aspecific area in your photograph.
-maybe adding a dynamic element to the picture would bring more life to it, like a fish swimming in or out of the frame or maybe towards the coral in question...
where in europe are you now as I could indicate some auqrium displays or LFS to visit in some European coutries that I have visited.