3 ms·

Any idea what the reason for that is? Is it simply because the shallows are darker and colder?

• adrian_b 3y ago
  It is not known for sure, but the most plausible explanation is that during the last Ice Ages the crabs and most fish have disappeared from there due to low temperatures. The disappearance of these predators has allowed other animal groups to flourish, while in other places those groups are restricted to higher depths, where such predators are also absent.
  • geor9e 3y ago
    >due to low temperatures Are you sure that's it? Sea water doesn't get any colder than a couple degrees below 0C, so the whole antarctic and arctic seas are all very similar temperatures no matter what part or what depth you're at. The crabs and fish have antifreeze protein in their blood too.