R code used to produce the graph shown below.

len <- seq(0.3, 4, .1) 
matplot(len, predict(model, newdata=data.frame(length=len), 
                     type="probs"), type="l", cex=mycex, lwd=3, col=c("darkblue", "blue", "black"), 
             xlab="Alligator length", ylab="Probability")