Creationists and evolutionists are probably agree on one thing: nature in its beauty reveals who knows the observe a certain logic, a remarkable organization. Some see God's work, on the other the result of a set of mechanisms grouped under the concept of evolution.
Still God is rather easy as the solution ... If God explains everything, it explains nothing not more ... "it snow thanks to God," the president is sent by God "... In God we trust ... too! I recently heard an interview with Michel Onfray, the philosopher who says that religion is a "mental disorder": Tasty!
But for the average philistine who observes a siphonophore, y 'it enough to ask questions. Faced with an organization as full and yet so simple! See these remarkable creatures closer ...
Presentation.
The siphonophores are cnidarians such as Hydra, jellyfish, sea anemones or corals. They are among the Hydrozoa (hydras group). These are marine organisms related to zooplankton although it can reach large sizes (up to 40m long). Like all cnidarians
the siphonophores grow from a larva called planula. The anterior part of the larva will give a nodule in the form of a jellyfish pneumatophore, while the base will grow and provide a first filament fishermen. Between these two zones will develop swimming bells and other filaments fishermen.
Ultimately each colony consists of a part that allows nectosome displacement and waterline and a siphonosome composed of identical units to each other and including each time a filament fisherman's cormidies.
Casting
Who does what in a siphonophore? Take the example of the kind Halistemma: a siphonophore where each unit is individually and arranged on a linear axis stolon.
Still God is rather easy as the solution ... If God explains everything, it explains nothing not more ... "it snow thanks to God," the president is sent by God "... In God we trust ... too! I recently heard an interview with Michel Onfray, the philosopher who says that religion is a "mental disorder": Tasty!
But for the average philistine who observes a siphonophore, y 'it enough to ask questions. Faced with an organization as full and yet so simple! See these remarkable creatures closer ...
Presentation.
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| Physalia physalis |
the siphonophores grow from a larva called planula. The anterior part of the larva will give a nodule in the form of a jellyfish pneumatophore, while the base will grow and provide a first filament fishermen. Between these two zones will develop swimming bells and other filaments fishermen.
Ultimately each colony consists of a part that allows nectosome displacement and waterline and a siphonosome composed of identical units to each other and including each time a filament fisherman's cormidies.
Casting
Who does what in a siphonophore? Take the example of the kind Halistemma: a siphonophore where each unit is individually and arranged on a linear axis stolon.
- The nectosome (from the Greek "nekton" swimming) is like the engine of siphonophore, it includes:
- The pneumatophore: This small vesicle will form a pocket filled with gas (composed of argon, nitrogen and oxygen) will floatation.
- The swimming bells: in the manner of small jellyfish this will allow the propulsion of siphonophore by contracting to expel the water at the center of the bell.
- The cormidies comprising the siphonosome include every time :
- A bract: it is a flat element that protects the rest of the cormidie
- dactylozoïde or cystozoïde A: Who has a role in excretion of waste
- gonozoïdes One or more males and females produce reproductive cells necessary the formation of new larvae
- gastrozoïte A: comprising a cavity and a filament gastrovascular fisherman who will bring the prey into the cavity of gastrozoïte.
- Sometimes other items: dactylozoïde, cystozoïde ...
A well-armed warship!
siphonophore The kind of the best known is probably Physalia physalis (see above), whose name comes from the Greek "phusalis" means galley and Portuguese, is also the common name this species. This name probably comes from martial over the pace of pneumatophore in boat hull, as the presence of filaments fishermen equipped with stinging cells: the cnidocytes. These cells
characteristics gave their name to the group of cnidarians. These are real lassos / spears wrapped in a blister under pressure: the nematocyst . A cnidocil the top of the cell can trigger the release mechanism of filament wound in the nematocyst stinging.
siphonophore The kind of the best known is probably Physalia physalis (see above), whose name comes from the Greek "phusalis" means galley and Portuguese, is also the common name this species. This name probably comes from martial over the pace of pneumatophore in boat hull, as the presence of filaments fishermen equipped with stinging cells: the cnidocytes. These cells
characteristics gave their name to the group of cnidarians. These are real lassos / spears wrapped in a blister under pressure: the nematocyst . A cnidocil the top of the cell can trigger the release mechanism of filament wound in the nematocyst stinging.
The prey in addition to suffering the effects of the stinging toxin contained in the nematocyst may, if its size allows it, find themselves trapped, wrapped by the filament. The target is then returned to the mouth or entrance of gastrozoïte. This formidable weapon emerged early in the history of life may prove fatal even for large organizations such as Human Rights (see eg jellyfish Chironex fleckeri )!
was therefore among siphonophores a sort of "angling" giant mass to capture small prey throughout the area covered by the filaments fishermen. This efficiency is often enhanced by bioluminescence and Tenille "lures" that mimic copepods (planktonic crustacean) whose purpose is to attract fish.
was therefore among siphonophores a sort of "angling" giant mass to capture small prey throughout the area covered by the filaments fishermen. This efficiency is often enhanced by bioluminescence and Tenille "lures" that mimic copepods (planktonic crustacean) whose purpose is to attract fish.
[Left: View of swimming bells of siphonophore. Right: Examples of tentilles (small tentacles) mimic bioluminescent marine copepod. in a kind of siphonophore Erena (Haddock, Science - 2005)]
Super-organism ... yes and no!
Each siphonophore is will be understood, consists of a specialized unit and assembled into a single structure. Each of these units can be compared with a polyp (a cnidarian fixed) or a jellyfish (eg swimming bells). It has several highly specialized units in various functions. In this sense a siphonophore is a colonial cnidarian, ie composed of individuals with the same genotype puisqu'issus of the larva and attached to each other. We're talking super-organism because each individual contributes to the survival of the entire structure.
But what about the human body for example? Isolate as a self gastrozoïte do not necessarily make more sense than isolating self as a body involved in proper functioning of the human body.
is why the term super-organism can not in my opinion apply only to social species which individuals are distinct, because physically separated, and participating in the functioning of society which is considered the super-organism. This is the case of bees who are dedicated to the hive, for example. The problem is actually to solve the question of individuality ... The philosophy is she everywhere?
[ Some video siphonophores at work: ]
Links:
- http://www.siphonophores.org/ : for learn more about the lures (English)
- Other video: http://vimeo.com/9561696 and http://vimeo.com/10784386
- Quick on Science Direct (English)
- Wikipedia http://fr.wikipedia.org/wiki/Siphonophorae
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