So I have a cephalopod question that pertains to their sense of hearing; can cephalopods hear? I ask because I know other vertebrae don't need ears like us, (lizards, tortoises, other reptiles and amphibians,) but cephalopods aren't vertebrae, so do they hear like we do? Or do they even need to hear, being underwater and all? If they don't hear, do they have another sense to make up for no hearing? Thanks! (I'm not a scientist btw, but I love the blog!)
This is not something that we know very much about, but from what we know so far, pelagic squid can hear at least low-frequency sounds, but octopuses don’t seem to be able to hear. I actually did my undergrad thesis on cephalopod hearing! A scientist named Aran Mooney played sounds for squid and monitored their brain activity and they responded to low-freqency sounds but not higher freqencies. I haven’t done a literature search lately though so we might know more now than we did in 2011. I tried to train octopuses to associate a sound with food, but either they didn’t figure out they were associated (and octopuses are pretty good at learning that kind of thing), or they didn’t hear it. Since the results were negative, we can’t really say “these animals can’t hear” we can only say that these experiments showed no evidence of hearing ability.
In terms of HOW they’d be able to hear, cephalopods have a statocyst in their heads that are accelerometers but may also be important for hearing.
Here’s some more information on that study by Aran Mooney! http://www.whoi.edu/oceanus/feature/scientists-find-that-squid-can-detect-sounds