Sorry been busy recently. I think its coming along but I think you need to figure out where it is that you are going with the design. For instance how the mouth would work or why does it have horns on only its head and tail; the horns on the head are too far back to be for defense so I wonder what they could be for. Perhaps they are there in case it gets eaten but the beast strikes me as something that is very large. Also I can't really make out any kind of skeletal structure. I understand that its in it's base pose still but it looks really stiff and ridged. I wish you posed it more like the concept sketch. Also I am wondering how this thing actually swims. Does it use it's fins or it's tail? Its a hard call because if it uses its tail like a snake or an "eel" then what would the flippers need to be so big and functional for.
Of course this could be more of a cartoony creature which would then explain the lack of skeleton, and strange mouth as well as flippers that could be arms and legs stand ins. But the texturing and the renders suggest that it is to be more realistic so its a bit confusing.
All the other models are much better but you still need to pay more attention to the skeletal structure of these things so you get away from the cartoon gumby look—unless of course thats what you are shooting for.
The spider thing is by far the best I think but the textures do not do it justice and make it look very cartoony like a video game. You should really make use of your reference. In this day and age you can easily punch up anything you like online. If you want the bug to have some meaty parts then search for the kind of meat that you want it to look like and model and texture off of that. It brings to mind the old saying that they used to constantly remind us of when I was doing comics and that is, "if you pull it out of your mind then it will usually ends up looking like you did". Like I said its never been easier to get your hands on reference so make use of it.
I hope that you keep coming back and being a part of this community I sure appreciate looking at your stuff. Allot of material gets posted up everyday and its easy for things to get lost or overlooked. I also would love to see you retexture that spider creature; thats my favorite! And the eel beast looks interesting as well and I can't wait to how that plays out.