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jellyfish


jellyfish
Photo Information
Copyright: Morten Bjerregaard (mbhhas) (15)
Genre: Animals
Medium: Color
Date Taken: 2007-03-31
Categories: Seascape
Exposure: f/4.5, 1/30 seconds
More Photo Info: [view]
Photo Version: Original Version
Date Submitted: 2007-04-01 7:16
Viewed: 3932
Points: 2
[Note Guidelines] Photographer's Note
Jellyfish are marine invertebrates belonging to the Scyphozoan class, and in turn the phylum Cnidaria. The body of an adult jellyfish is composed of a bell-shaped, jelly producing substance enclosing its internal structure, from which the creature's tentacles are suspended. Each tentacle is covered with stinging cells (cnidocytes) that can sting or kill other animals: most jellyfish use them to secure prey or as a defense mechanism. Others, such as Rhizostomae, do not have tentacles at all. To compensate for its lack of basic sensory organs and a brain, the jellyfish exploits its nervous system and rhopalia to perceive stimuli, such as light or odor, and orchestrate expedient responses. In its adult form, it is composed of 9498% water and can be found in every ocean in the world. Most jellyfish are passive drifters that feed on small fish and zooplankton that become caught in their tentacles. Jellyfish have an incomplete digestive system, meaning that the same orifice is used for both food intake and waste expulsion. They are made up of a layer of epidermis, gastrodermis, and a thick layer called mesoglea that actually produces a main part of jelly and it separates the epidermis from the gastrodermis.

Their shape is not hydrodynamic, which makes them slow swimmers but this is little hindrance as they feed on plankton, needing only to drift slowly through the water. It is more important for them that their movements create a current where the water (which contains their food) is being forced within reach of their tentacles. They accomplish this by rhythmically opening and closing their bell-like body.

Since jellyfish do not biologically qualify as actual "fish", the term "jellyfish" is considered a misnomer by some, who instead employ the names "jellies" or "sea jellies". The name "jellyfish" is also often used to denote either Hydrozoa or the box jellyfish, Cubozoa. The class name Scyphozoa comes from the Greek word skyphos, denoting a kind of drinking cup and alluding to the cup shape of the animal.

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Critiques [Translate]

Hello Morten!
Very beauty presentation of very nice (and small I suppose) species :)
Picture has great details and fantastic colours and contrast (especially the stomach pouches are well visible :>).
Very interesting note too.
Best greetings,
Radomir

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