Beaks

Discussion in 'Physiology and Biology' started by Phil1078, Aug 25, 2010.

  1. Phil1078

    Phil1078 Blue Ring Registered

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    So how strong is the cephalopod beak roughly? It would seem that the relatively small beak would limit the size of the food consumed by the ceph. The arms can only hold an item for so long before tiring. Carnivorans (mammals) are my main interest, so I was just relating the relative attributes of the predators. Cephs are somewhat similar to felids, especially those with hooks on their arms and tentacles. However, where the cat would impliment a kill bite, what does the ceph do? I know some octopus are venonous, so I can see how it works for them, but larger predatory squid such as Dosidicus.... I am not so sure how they could tackle something their size or larger.

    I am really not the most well-informed ceph enthusiast, so bear with my errors and help me rectify them!
     
  2. Level_Head

    Level_Head Vampyroteuthis Registered

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    Here's what I've gathered:

    So far as we know, all of the cephalopods seem to be venomous to their intended prey. As you pointed out, the beaks on smaller animals present a size limitation, but even some of the larger ones use a different technique: They use their radula -- essentially a tongue with rasp-like teeth -- to bore a small hole in a hard shell or exoskeleton. Then they can inject their venom/saliva into the victim.

    The injection can accomplish multiple purposes: It immobilizes the victim (reducing the predator's exposure to injury), and in some cases actually dissolves the tissues involved. And especially for bivalves, it attacks the muscles holding the shells together allowing them to be opened.

    While different species use variations on the theme, this arrangement seems pretty broad across the reef-dwelling octopuses, cuttlefish and nautiluses. The open-ocean predators like the Humboldt Squid and not usually going after hard-shelled prey; they can take bites of their victims — and do. The Patagonian Toothfish (we call it "Chilean Seabass" in the US) seems to be a favorite of the largest squid, and we have often retrieved half-fish with large chunks missing.

    In each case, the chewing (apparently with the help of the toothed tongue) and swallowing is done very carefully, as cephalopods have the odd arrangement of having their esophagus-equivalent -- their throat -- passing through the middle of their brain.

    When an octopus eats you, he has you in mind after the meal, literally.

    There are reports that octopuses have been found dead from apparently a too-hasty meal; an urchin spine protruded from the gut into the brain, killing the animal that was in the process of devouring it. I used this as a minor plot point in one of the books I wrote in which the protagonists are evolved octopuses.

    Young octopuses, even at the paralarva stage, seem willing to attack creatures of equivalent size, and there is a popular YouTube video of a Great Pacific Octopus attacking and killing (and subsequently eating much of) a shark that outmasses him by a good margin:


    I apologize for the poisonous commercial and sappy narration. The situation is interesting, and it addresses your point, I think.

    As for Dosidicus gigas, the jumbo squid has been known to attack and kill others of similar size. One instance involved attaching a camera to the fin of one female, which put the watchers in the unhappy position of watching as this female was torn to pieces by other members of the shoal. That footage was featured on one of the recent cephalopod documentaries, but I don't recall which one. It was probably one focused on that species in particular.
     
  3. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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  4. Level_Head

    Level_Head Vampyroteuthis Registered

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    You never did get an answer to your original question about the strength of a cephalopod beak.

    Pure chitin is not very strong; it's a supple, leathery material. But chitin reinforced with various other substances can be quite strong; this is the case in cephalopod beaks.

    I did not realize that even octopus suckers contain chitin; this paper discusses the various chitin combinations and uses in cephalopods:
    http://www.scopus.com/record/displa...origin=inward&txGid=9BNwwxJMv2aLJH-G5R6yvgp:2

    This is not about cephalopods particularly, but is an interesting paper on the strength and structure of various biological construction materials including chitin. The animals addressed are toucan and hornbill, crab exoskeleton, and (closest for us) conch shell. Some of the strength numbers are impressive indeed; 10,000 times the strength of the equivalent non-biological molecule.
    http://www.nd.edu/~rroeder/ame60646/slides/biocomposites.pdf

    But moving from the general to the specific, here's the paydirt: A detailed analysis and strength testing of squid beaks, using your Dosidicus gigas as the source of the beaks:
    http://www.materials.ucsb.edu/~zok/PDF/JumboMiserez.pdf
    Page 147 in the paper provides a nice diagram placing squid beaks graphically in context with other materials.
     
  5. Steve O'Shea

    Steve O'Shea Colossal Squid Supporter

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    You need only have one of these (squid or octopus) envelop your hand/arm to realise just how strong these animals are. Give man an octopus any day - a squid latched onto you hurts like MAD (due to those sucker rings). I wouldn't be too concerned about the size of the beaks - there's a lot of power in those writhing arms.
     
  6. OB

    OB Colossal Squid Staff Member Moderator

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    Some beaks WOULD have me worried....

    [​IMG]

    WRT your original query, Dosidicus quickly gnaws its way towards any hapless tentacle trapped fish' spinal chord in seconds, that's how it achieves the kill.
     
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  7. aziegler802

    aziegler802 Larval Mass Registered

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    Hello, I am an undergraduate very interested in working with squids especially feeding behavior and the mechanism of their beaks. Unfortunately I am not able to catch my own specimens to observe them in any way. I am also a cephalopod enthusiast and would really love one (or several!) as a collectors piece. My first thought was to approach commerical fishermen who discard them anyway but they are not very common in my area. Does anyone have any suggestions about how or where to acquire a decent sized squid beak for a reasonable price? Thanks!
     
  8. gjbarord

    gjbarord Sepia elegans Staff Member Moderator

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    What do you mean by decent size? Are you only interested in squid beaks? Cuttlefish, octopus? I have several beaks of Enteroctopus dofleini, though I will have to remember where I stored them... There are several large squid species trawled up along the west coast. Not sure how you could contact local fisherman there? Perhaps contacting one of the universities along the coast?

    Greg
     
  9. aziegler802

    aziegler802 Larval Mass Registered

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    I am most interested in squid beaks but really any would do for the time being. I know that the beaks of smaller squids are quite small which is basically the most common around here so I just meant a beak that I could actually see well but I've never really seen how the size of the beak compares to the body in person. I am pretty inexperienced when it comes to cephalopods unfortunately but I am really hoping to improve my knowledge and widen my experiences to focus on cephalopods more in graduate school. I may be taking a summer course at Washington University in which case I will hunt down some beaks! I will have to see what I can do about other Universities. Thank you so much for the help and a really fast response!
    ~Amanda
     
  10. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    Amanda,
    Do you have an asian food market near by? If so you can buy whole frozen squid (sometimes fresh as well) and frozen octopus (look up HMart and Assi or just try Googling Korean food markets with your city and state as part of the search). Our sort of local Assi had whole octopuses that were cantelope size so you may find at least viewable beaks. The squid I brought home were very small and the beaks tiny but these were fresh and I was looking for the smallest in the barrel. You might even try asking at the food counter where they clean the squid if they have any beaks (be prepared to explain by pointing and with patience as many of the people are still learning English at our markets and their first languages vary).
     
  11. aziegler802

    aziegler802 Larval Mass Registered

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    There seem to be quite a few asian markets just north of me. I am not familiar with any so I will have to visit some in the very near future and see what I can find. Good tip, thanks!
    ~Amanda
     

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