This pattern for a very realistic crocodile has 6 separate pieces, with the body pieces reverse sides out. Any suitable DK yarn could be used, or 4 ply + smaller needles for a smaller crocodile. Gauge is not really important, although if you are a very slack knitter, the stuffing will show through, so go down a needle size.
Pipe cleaners are needed for the legs, and 2 beads for eyes.