1) well it's not like the animal is alive and kicking for ripples to be made in water. He just might have died due to drowning and the anaconda is just taking it up
2) Anaconda's CAN be that big... the largest measured was 38 FEET...
3) They are that strong !
4) it's a canyon scene, there is no direct light, everything is illuminated because the light reflects off the rocks. Hence shadows are not visible
5) and if you look at the picture the anaconda is trying to curl ! and we don't know if he managed to pull that animal out.
I mean I am not claming it's real or fake. I am just saying that this is possible. Snakes are unbelieve creatures, especially anacondas, you can never underestimate their powers. So this is very much possible. I personally don't think it's a photoshop. Though it might be...