Snails... We have some kind of huge garden snails appearing lately (read since the last 10 years or so). Try as one might, it's impossible to avoid them when driving. These snails do not appear to have red blood - I doubt they have blood at all. Wikipedia tells me blood's red colour is due to haemoglobin - which serves to transport oxygen.
How do snails (and any other animals that do not have red coloured blood) get oxygen? Or, do such animals need no oxygen at all?