Hippopotamus adaptations.

[thatchick]

hello all

i'm doing a biology project on the adaptations of a hippopotamus
(structural, physiological, behavioural and reproductive)

and i'm having trouble finding some for the physiological adaptations. i've been on a number of sites but seem to only be finding the other types of adaptations.

so far i've got:

- when they dive underwater their nose and ears close to prevent water getting in (is this physiological)
- their jaw can pick up soundwaves under the water.

so any links/answers would be appreciated.
thanks!

[JackBean]

the first one is IMHO more structural or anatomical...