This is my first post, I registered here today.I am from Russian, therefore sorry me for my english.This is my first quite big project, but I am working in Blender since 2013 year.I started this project today,more needs to be done a lot, and now - crude ant.I ask constructive criticism.
Allright, nice work! Nice start! When I have something like that, I usually retopo it and then bring it in sculpting software again to scuplt finer details on nicer topology 
The head is missing mandibles, though… but they as well could be added after retopo. I would not in general weld parts of a creature like that together, because it has shell (treat it more like a hard surface model, I’d say))
Otherwise nice, as I said! Looking forward to see your progress!
Thanks a lot) Yes, I need to add jaw and other small details,and then make retopology.But I am difficult enough to add really small details to the model, I need more training in sculpting.I think that this work will be a good experience for my future.Thanks for the tips)
Update: I add jaws and some small details.
And made retopology.Before(1236181 triangles)/After(259696 triangles).
you could still remove some of the loops in there if you have subsurf enabled !
but nice work here
happy cl
It looks great so far. I think the surface of the jaws should be more convex, as in the reference photo.