Spiders?

Jumping spiders are the geniuses of their size/energy tier. It almost makes no sense that so few neurons should be so capable, but my favorite hypothesis is that nature golf coded a specially tuned, unexpectedly flexible, highly optimized recurrent architecture that sequentially overthinks to simulate a far higher intelligence level than its size profile would suggest.

Are written like mammals in this book, just with a different way of comminucating.

Tiger shrimp are also in the picture eventually.