Beaks

[olgacguven]

In some of the scientific journals about the beak analysis I have found some terms about beak measurements such as Lower rostral length (LRL) and upper rostral length (URL). I will be very grateful if someone can explain me these terms. If its possible with figures. thanks....

 

[Graeme]

Gaagh! Mouthpart Terminology!! erm..... Right, I'm guessing that'd be the upper and lower half of the beak. I'm not toally clued up on Ceph mouthpart morphology, but that would be my best guess! There's so many words describing different parts of mouthparts, which in Arthropods in very easy since all the mouthparts are practically seperate. But when you start getting into animals with "2" mouthparts then it starts to become hazy.

Graeme

 

[OB]

Hi there Olgac!

I trust you'll find http://www.museum.vic.gov.au/sciencereports/docs/6_lufigs1.pdf helpful, to this respect.

Cheers,

Olaf

 

[olgacguven]

thank you very much for your interest....

 

[Jean]

Olac

Are you measuring beaks???? What species??? I've measured a wee few Nototodarus sloanii beaks and the odd Moroteuthis ingens ones........................what fun One wee bit of advice use digital calipers if you can.........so much easier on the eyes!

Cheers

J

 

[olgacguven]

I am planing to measure three difrent species in Antalya Bay TURKEY (S. officinalis, L. vulgaris, E. cirrosa)

 

[Jean]

I am planing to measure three difrent species in Antalya Bay TURKEY (S. officinalis, L. vulgaris, E. cirrosa)

That sounds interesting. Are you doing RL to mantle length regressions? It's nice to hear someone else measuring gazillions of beaks!!!!!


J

 

[olgacguven]

I hope so. For the present I am collecting past journals to determine useful metod.

 

[Steve O'Shea]

You'll have a bit of 'fun' measuring rostral length of the lower beak in an octopod, given the lack of a clearly defined 'jaw angle'. Prepare to pull your hair out; differentiating beaks can be tremendous fun (and equally frustrating). When doing so, especially when comparing closely related taxa, keep in mind that the differences between them might not be obviously mathematical (especially if you limit yourself to a few basic measurements), but in some other less-easy-to-define character state.

Take a good look at those beaks ... throw your ruler away .... and understand how they are put together. Differences are remarkably subtle, but once familiar with beak construction they are as distinct as apples and oranges (or pears as those in the UK might say).

 

[Jean]

yup good ol' rostral gap, hood length, crest length, wing length.............

J

 

[Gayla]

A late entry on this thread, I know ...

But I want to second what Steve said about throwing your ruler away. Measuring is important for some things, but I think it can slow down your learning process. Certainly you should start by reading what characters and ratios are important to look at, but once you know which points to key in on, then spend your time browsing pictures of beaks and the beaks that you have.

What helped me the most was looking at a large number of beaks and developing an intuitive sense for them. Your eyes and your brain are very good at perceiving proportions and integrating visual information that's just too complex to be described in ratios, and the faster you can train them the easier your job will be. You want to be able to look at a beak and your mind automatically go through a check list (jaw angle, hood-edge ratio, lateral wall features, wing fold, hood-crest gap, overall "posture", etc...) and family name or two pop into your head. I think the fastest way to get there is to look at as many beaks as possible as often as possible. The information seems to leak from my brain rapidly, so I try not to let more than 4-5 days go by without looking at beaks from some source.

Then measure if you must.

Just my 2 cents ... good luck to you!

Gayla

 

[Jean]

Hi Gayla,

What beaks were you looking at??????

J

 

[Gayla]

Beaks from the stomachs of Yellowfin and Bigeye Tuna off Hawaii. Beaks are predominantly Ommastrephidae, Cranchiidae, Histioteuthidae, good amount of Onychoteuthidae and Enoploteuthids also, but I have about 25 diff families represented including some Sepiolids (Heteroteuthis) and Octopods. We're getting resolution between the diets at the family level, so I'm not going to genus/species unless it's obvious. Also, I'd NEVER get done if I had to get much further with my id's. I have 3000+ id's to make; I have a good number of bodies but most are only beaks.

 

[Jean]

What fun The only diet stuff I'm dealing with are the contents of squid stomachs and on the whole they tend to eat members of their own species (among the fish etc).............but the fish otoliths I have some that look like dust grains but under high power they are different AAAAAAAAAAAAAAAAARGH once had some viper/dragon fish oto's but couldn't id them any further than to that family.

Then there are the krill eyes but that's a whole nother story

J

 

[Steve O'Shea]

Beaks from the stomachs of Yellowfin and Bigeye Tuna off Hawaii. Beaks are predominantly Ommastrephidae, Cranchiidae, Histioteuthidae, good amount of Onychoteuthidae and Enoploteuthids also, but I have about 25 diff families represented including some Sepiolids (Heteroteuthis) and Octopods. We're getting resolution between the diets at the family level, so I'm not going to genus/species unless it's obvious. Also, I'd NEVER get done if I had to get much further with my id's. I have 3000+ id's to make; I have a good number of bodies but most are only beaks.

Hi Gayla; any problematic beaks in that lot? Felipe and Emma here are doing similar work on the Sperm Whale & Pygmy Sperm Whale respectively. Keying out the smaller-bodied taxa using available literature is just about impossible; they've gone through and developed a reference collection of beaks from actual squid.

I cannot imagine you 'discarding' the beaks afterwards (end of your study), but if they don't have a home then I'd be all-too-happy to wave my hands around and look after them for you in the collections here. I'd love someone to do comparable work on some of our tuna, sharks and marlin - it is such an interesting, challenging and rewarding area of research.