• Question: Why have cephlapods such as squids and octopuses evolved to have their mantle on the inside of their skin?

    Asked by leonard004 to Ed, Katie, Sam, Steve, Vera on 14 Jun 2011.
    • Photo: Katie Marriott

      Katie Marriott answered on 14 Jun 2011:

      Sorry i don’t know! But maybe it has something to do with protecting the nervous system?

    • Photo: Sam Tazzyman

      Sam Tazzyman answered on 14 Jun 2011:

      I am not sure exactly what you mean. In lots of cephalopods the mantle is like a protective layer inside of which is the organs – a bit like a human ribcage, though of course not made from bone (cephalopods, like all molluscs, are invertebrates).

    • Photo: Steven Daly

      Steven Daly answered on 14 Jun 2011:

      It makes them more flexible, which may well aid them in their life, and escape from predators.

    • Photo: Vera Weisbecker

      Vera Weisbecker answered on 14 Jun 2011:

      You mean the the shell, right? That went from a mussel-like ancestor with an outside shell into the cephalopod body, where it helps keeping the shape (they are pretty soft). In many squids, this ex-shell even evolved into a firm white spongy oval thing inside (you may know them from bird cages). They use that to regulate their buoyancy – if they need to be heavier, they reduce the gas content in the spongy thing (what is the English name for this???) and if they need to be lighther, they increase it.

Comments

  • Photo: Glo

    Glo commented on :

    I’m going to zone jump here and toss in a little info, since this is in my field. 🙂 The mantle includes the skin – it’s just the generic name for that portion of the body. We have arms and legs, cephalopods have arms and a mantle. If you mean why don’t they have shells on the outside, well, somewhere along their ancestral history, it became more of a nuisance than a benefit, so it was ‘selected against’. Shells take energy to make – and cephalopods have evolved AMAZING camouflage systems that help keep them safe. Some cephies, like cuttlefish and squid, have maintained an internal ‘shell’ that they use for controlling buoyancy, others, however, such as the octopus have done away with it all together! Check out these super cool websites, if you’d like to learn more:
    http://giantsquid.msstate.edu/LessonList/dissection.html
    http://www.ucmp.berkeley.edu/taxa/inverts/mollusca/mollusca.php