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 Post subject: Cuttlefish on SA shores
Unread postPosted: Tue Aug 18, 2009 9:19 am 
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I saw a program on the tube the other day... :hmz:
How many different types of cuttlefish have we got the shores of South Africa ?
Can some-one please explain how they alter their colours with a blink of the eye ?

:big_eyes: These are truely amazing sea creatures and would like to know more about them and if you have any pictures, could you please some them with us ? :pray: :pray:

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 Post subject: Re: Cuttlefish on SA shores
Unread postPosted: Tue Aug 18, 2009 9:29 am 
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For those that don't know what cuttlefish are: link

I like them a lot, but have yet to see them in the wild.

My birds like them too, the cuttlebone, it's internal skeleton, is a very much prized source of calcium for them. Especially when the girl is laying eggs again.

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 Post subject: Re: Cuttlefish on SA shores
Unread postPosted: Tue Aug 18, 2009 5:53 pm 
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Fascinating creatures indeed bentley! :thumbs_up: :thumbs_up:

Image

Cuttlefish belong to the Cephalopoda class and includes squid, octopuses, and nautiluses). Although they are known as fish, they are mollusks and not fish! Recent studies indicate that cuttlefish are among the most intelligent invertebrates. Internationally there are 120 species of cuttlefish recognized. I am not sure how many species are in South African waters though!

Cuttlefish have eight arms and two tentacles furnished with suckers, with which they secure their prey.

They have a life expectancy of approximately 2 years and feed on small mollusks, crabs, shrimp, fish, octopuses, worms, and other cuttlefish. They are being preyed upon by dolphins, sharks, fish, seals and other cuttlefish.

Their cuttle-bones are porous and used for buoyancy by changing the gas-to-liquid ratio in the chambered cuttle-bone.

Cuttlefish eyes are among the most developed in the animal kingdom.
The blood of a cuttlefish is an unusual shade of green-blue. The reason for this is the fact that they use the copper containing protein hemocyanin to carry oxygen instead of the red iron-containing protein hemoglobin that is found in mammals. They have 3 separate hearts to pump their blood. Two hearts pump blood to the pair of gills and the third pumps blood to the rest of the body.

Photo of 2 Cuttlefish:
Image

Herewith something interesting facts about their ability to change colours:

Cuttlefish are sometimes referred to as the chameleon of the sea because of their remarkable ability to rapidly alter their skin color at will. Their skin flashes a fast-changing pattern as communication to other cuttlefish and to camouflage them from predators. This color-changing function is produced by groups of red, yellow, brown, and black pigmented chromatophores above a layer of reflective iridophores and leucophores, with up to 200 of these specialized pigment cells per square millimeter. The pigmented chromatophores have a sac of pigment and a large membrane that is folded when retracted. There are 6-20 small muscle cells on the sides which can contract to squash the elastic sac into a disc against the skin. Yellow chromatophores (xanthophores) are closest to the surface of the skin, red and orange are below (erythrophores), and brown or black are just above the iridophore layer (melanophores). The iridophores reflect blue and green light. Iridophores are plates of chitin or protein, which can reflect the environment around a cuttlefish. They are responsible for the metallic blues, greens, golds, and silvers often seen on cuttlefish. All of these cells can be used in combinations. For example, orange is produced by red and yellow chromatophores, while purple can be created by a red chromatophore and an iridophore. The cuttlefish can also use an iridophore and a yellow chromatophore to produce a brighter green. As well as being able to influence the color of the light that reflects off their skin, cuttlefish can also affect the light's polarization, which can be used to signal to other marine animals, many of which can also sense polarization.

(Source: http://en.wikipedia.org/wiki/Cuttlefish )


Last edited by TheunsH on Tue Aug 18, 2009 8:24 pm, edited 1 time in total.

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 Post subject: Re: Cuttlefish on SA shores
Unread postPosted: Tue Aug 18, 2009 8:10 pm 
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Often get the bones washed up on the beach near me and the empty egg sacs (Mermaids purses we used to call them)

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 Post subject: Re: Cuttlefish on SA shores
Unread postPosted: Wed Aug 19, 2009 10:55 pm 
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Thanks Theuns for the awesome pictures and info on them cuttlefish :thumbs_up: :wink:

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 Post subject: Re: Cuttlefish on SA shores
Unread postPosted: Mon Aug 31, 2009 12:39 pm 
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Thanks for the cool info! I had no idea they looked like that- found a bone at WCNP a while ago.


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 Post subject: Re: Cuttlefish on SA shores
Unread postPosted: Thu Sep 10, 2009 1:16 am 
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Dotty wrote:
Often get the bones washed up on the beach near me and the empty egg sacs (Mermaids purses we used to call them)

The eggs of cuttlefish are about the size of lentil or small peas and the mermaids purses are normally shark eggs.
See here.

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 Post subject: Re: Cuttlefish on SA shores
Unread postPosted: Sun Oct 25, 2009 7:37 am 
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When we scubadived in the Knysna lagoon a couple of years ago, we saw two of them that were as big as a grown man's torso (Their body part that is) and I couldn't believe my eyes. There are lots of them down there but about the size of a man's hand. When I spoke to Mr Peet Joubert (Nature conservation's office on the jetty) he said that they have seen some that were about six feet (1.8m) in length. So, they DO get quite big. Their underside glimmers with a neon green light (With wavy, changing, black lines) when you shine a light on them. VERY BEAUTIFUL to see.

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