On Wed, Mar 05, 2014 at 05:52:20PM -0800, [email protected] wrote: > > > I'd always defer to an aussie on sharks...but I'm curious how they get the > oxygen onto their gills. Could it be they exploit currents that certain > kinds of cave might produce? What happens when two windows are open on a > room sort of thing? Are those cave sharks quite small, out of interest? > Smaller fish have less oxygen demand...hence really little one don't seem > to need much of a sleep strategy for keeping the flow on the gills.
The sharks in question are 2-2.5 metres in length, so they're by no means small fish. But fish, in general, have lower metabolic requirements than say a mammal of the same body mass, as they're ectothermic. In terms of the caves, these are open to the ocean, so with the swell, I expect the oxygen concentration inside to be similar to that of the open ocean. > > > > > Re dolphins, the problem is that they cannot breathe underwater, so > > need to surface periodically to do so. Consequently, they need quite a > > bit of brainpower (essentially to be awake) to be active all the > > time. Fish (like sharks) do not face this problem, so can rely on > > autonomous "breathing" via their gills. > > > Could be, although larger fish would feasibly have oxygen needs > that couldn't necessarily be supplied by remaining stationary. Could be - I have heard the factoid that some sharks need to keep moving. What I don't know is whether it is an urban myth or not. -- ---------------------------------------------------------------------------- Prof Russell Standish Phone 0425 253119 (mobile) Principal, High Performance Coders Visiting Professor of Mathematics [email protected] University of New South Wales http://www.hpcoders.com.au ---------------------------------------------------------------------------- -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
