Hooks and suckers

The hooks seem to grab everyone’s attention (pun intended). Other squid families have hooks on the arms, or the tentacles, or both, but the colossal squid is the only hooked squid in its family (the Cranchiidae, about 20 species). It possesses hooks on each of the eight arms, and also on the two long tentacles, but the arm-hooks and tentacle-hooks are very different.

The tentacular hooks (above and below) are the swivelling hooks. Each sits on a short stalk, flush with the oral surface of the tentacle club, in a flattened depression that allows the flattened ‘back’ surface of the hook to rotate. The hooks can swivel 360 to 720 degrees, but it is not known whether the squid actively controls each hook individually, or whether the hooks swivel passively once latched onto the prey, in order to keep the best grip. There are 22 to 25 hooks in two rows on the middle part (manus) of the tentacle club, and each row is flanked by a row of tiny marginal suckers. The swivelling hooks are smaller than those on the arms and have only a singe main ‘claw.’

The arm hooks (below) do not swivel. They are set in a double row in the middle of each arm, preceded and followed by the more standard toothed suckers. The arm hooks are set in fleshy, very muscular sheaths and are strongly attached to the arms. They are likely to assist in holding and immobilising struggling prey as it is being killed and eaten. Most of the arm hooks have the main strong ‘claw’ (visible below), and also two smaller auxiliary cusps closer to the hook’s base, making them three-pointed and maximising their ability to hold and dig in. The base of each hook also has a complex structure that is set deep into the surrounding musculature.

- Kat Bolstad

13 Responses

  1. Noel

    I seen that in
    TV seven

    It’s the most largest squid ever! the colossal squid,

    it been extinct in February 22 2007 at Antartica.

    Reply
  2. raumati

    not the biggest squid i have seen

    Reply
  3. tepapamuseum

    Hey thanks Finn
    We like it too

    Have you seen our new Squid website
    http://www.tepapa.govt.nz/squid

    Lucy

    Reply
  4. Finn. M

    This squid rocks!!!

    Reply
  5. tepapamuseum

    You’re right Susan – we still know so little about the sea. And it is incredible how often new creatures are discovered. Even large creatures like the Colossal Squid!

    Reply
  6. Susan H

    This wonderful squid AGAIN shows us how little we really know about the ocean and what dwells there! What about the 95% still unexplored – what shall we find there? I can’t wait!

    Reply
  7. Jess

    i never knew there were 2 different kinds of hooks,
    i’m learning so much more about squid
    and i love it.

    Reply
  8. David Riddell

    Thanks, Kat. Dim distant memories of cranchiid characters are starting to come back to me. This is amazing stuff, I’m glued to this when I should be getting on with other things! I’ll put it all up on our home projector later when the examination gets under way, and sit back with a glass of wine!

    Reply
  9. chrispaulin

    I believe the systematic postition of Mesonychoteuthis is fairly stable – it has the hallmark character of the Cranchiidae, which is the head being fused to the mantle at three points (one dorsal and two ventral), where most other squids have a locking apparatus made of mantle and funnel/nuchal components that ‘snap’ together but aren’t fused. As far as I am aware Mesonychoteuthis also possesses the fluid-filled modified coelom (see this page on the Tree of Life) characteristic of the family.
    The Onychoteuthidae (my specialty :) ) have the above-mentioned locking apparatus system between the mantle and head (not fused), no fluid-filled coelom, and possess hooks solely on the tentacles.
    Genetic studies regarding relationships between squid families have come up with different results, and tissue for cranchiids is scarce. We have taken tissue from the smaller colossal squid for analysis.

    - Kat Bolstad

    Reply
  10. Alex

    Alex (age 7) from Adelaide says I wouldn’t want to be swimming along in the sea and be grabbed by those hooks. Actually what does the giant squid eat?

    Reply
  11. David Riddell

    I was staggered to learn from this post that Mesonychoteuthis is a cranchiid – I always assumed it was an onychoteuthid. What’s the basis for this? I thought at first it had to be a mistake and rushed off to that fount of all wisdom, Wikipedia, and thence to CephBase, to check. It seems, superficially at least, to be about as different as it is possible for a squid to be from the other cranchiids, which are delicate, transparent, gelatinous little things. Has the relationship with the cranchiids been confirmed with DNA studies? (In a previous life I studied enoploteuthids for my MSc thesis, hence the nerdy question.)

    Reply
  12. Robert

    I’m so glad these didn’t make the transition to land at the same time our ancestors did. :/

    Reply
  13. Alexa Seagrave

    WOW, what an incredible creature. I may well mention this in class tomorrow.

    Reply

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