I read this book when I as a kid (probably around 1988 or so, and it wasn't brand new when I read it) with some of the following elements:
- Tons of diverse sentient aliens, I remember a sentient whale type creature, a panda-like creature, ant-like beings (perhaps the villains), etc.
- Some aliens had one type of DNA, others had a different type -- and aliens of one type could not eat creatures of the other type
- A big space station full of these creatures
- Periodically all the sentient species in the galaxy get wiped out by something
- Sonic weapons