National Geographic Mag- Sailfish

National Geographic Mag- Sailfish

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National Geographic Mag- Sailfish - 15 October 2008 21:02:45

Neil Daws

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Joined: 5 June 2003
From: Algal bloom river
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I thought gamefishers may like this article.

National Geographic has a small article on feeding sailfish at present explaining the cells that allow the fish to change colour or light up.

An iridescent flash along the body, often in silvery blue stripes, adds to the effect. Darkly pigmented cells called melanophores are "like venetian blinds," says neurobiologist Kerstin Fritsches of the University of Queensland, in Australia. Ordinarily the animal appears dull, but "during stress or excitement, the cells contract their pigment to expose gorgeous metallic colors in the skin below.".

http://ngm.nationalgeographic.com/2008/09/sailfish/holland-text

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RE: National Geographic Mag- Sailfish - 15 October 2008 21:42:26

Neil Daws

Posts: 4090
Joined: 5 June 2003
From: Algal bloom river
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video
The Whirl

http://ngm.nationalgeographic.com/video/player?titleID=1579853604

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"If you cannot measure it, you cannot control it"
"If you cannot control it, you cannot improve it"

(in reply to Neil Daws)

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RE: National Geographic Mag- Sailfish - 15 October 2008 22:04:01

Neil Daws

Posts: 4090
Joined: 5 June 2003
From: Algal bloom river
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Below the melanophores lie iridophores, which produce color structurally rather than with pigment. These cells have layers of guanine crystals that reflect light; wavelengths of light bouncing off them interfere with each other, creating iridescent colors such as metallic blue and silver. The sailfish appear dark when the pigment inside the melanophores is evenly distributed across the cells. But the fish can draw pigment from the melanophores' branches into their core, allowing light to hit the iridophores below and the iridescent colors to flash through.

http://ngm.nationalgeographic.com/geopedia/Sailfish#Sailfish%20Color%20Changes%20

_____________________________

"If you cannot measure it, you cannot control it"
"If you cannot control it, you cannot improve it"

(in reply to Neil Daws)

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RE: National Geographic Mag- Sailfish - 30 October 2008 20:36:17

Lee Williams

Posts: 231
Joined: 26 May 2005
From: Broome
Status: offline

Excellent Neil.

Interesting how the sailfish stopped hunting with cloud cover. The reflected light is obviously important to their hunting technique.

Either that or they can't see in the dark.