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Tuesday, April 10, 2012

Cnidaria: Siphonophores (Jane and Allie)

There are approximately 10,000 species in the phylum cnidarian. They have special stinging cells called cnidocysts and a tissue that covers their outer body, which is connected to a gel-like substance called the mesoglea. Cnidarians use a nerve net and basic receptors to move and take oxygen from the water.

Marrus orthocanna




Many cnidaria live in colonies and appear as one organism; specifically: siphonophores, which resemble jellyfish. The most famous organism is the Portuguese Man o’ War, measuring 40-50 meters. 


Portuguese man o war




Siphonophores are made up of zooids that each have a specialized function and lack the ability to survive on their own. They are arranged like a locomotive, usually with propulsion at one end, and feeding, protective, and reproductive units trailing behind.


Mertensia ovum




Cnidarians use their cnidocysts around their mouth to immobilize their prey. Cnidarians eat organisms raging from the size of plankton to turtles, but obtain much of their nutrition from endosymbiotic algae and parasites. Each “feeding compartment” has its own tentacle and can catch and process food individually.


Apolemia




Most siphonophores are bioluminescent and can produce dramatic light shows when disturbed. Some, including many newly discovered deep-sea species, are fluorescent, iridescent, and capable of lightening to a milky white color. 


Video clipped from National Geographic's Worlds Deadliest Animals Costa Rica, during a segment about the siphonophore, Portuguese Man O' War.




In the past the only method of collecting siphonophores was trawling with large nets, which would break apart the delicate animal. Now our diving protocols, sampling, and diving technology has advanced, allowing us to enter their environment, identify the animals we want, and gently take them from the water without harming them. 




Dr. Phil Pugh describes what it’s like to come across a siphonophore in the deep sea with a submarine.


To see our sources and for more information on cnidaria and siphonophores, click on a link:


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