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http://powerforum.dk/viewtopic.php?f=25&t=22512
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Forfatter:  Ravnen [ 25 aug 2009, 14:25 ]
Titel:  dræber reje...

:shock: så har man set det med...

http://www.toxicfactory.com/remarkable- ... p-3890.php

Forfatter:  ae86 [ 25 aug 2009, 15:57 ]
Titel: 

Den minder mig om en Peacock mantis shrimp

Billede

her er lidt facts fra wiki

Citat:
... sometimes referred to as "thumb splitters" by modern divers — because of the relative ease the creature has in mutilating small appendages — mantis shrimp sport powerful claws that they use to attack and kill prey by spearing, stunning or dismemberment. Although it happens rarely, some larger species of mantis shrimp are capable of breaking through aquarium glass with a single strike from this weapon. It is for these reasons that they are often kept as solitary creatures in acrylic tanks...



Citat:
Both types strike by rapidly unfolding and swinging their raptorial claws at the prey, and are capable of inflicting serious damage on victims significantly greater in size than themselves. In smashers, these two weapons are employed with blinding quickness, with an acceleration of 10,400 g and speeds of 23 m/s from a standing start [8], about the acceleration of a .22 caliber bullet. Because they strike so rapidly, they generate cavitation bubbles between the appendage and the striking surface [8]. The collapse of these cavitation bubbles produces measurable forces on their prey in addition to the instantaneous forces of 1,500 newton that are caused by the impact of the appendage against the striking surface, which means that the prey is hit twice by a single strike; first by the claw and then by the collapsing cavitation bubbles that immediately follow [9]. Even if the initial strike misses the prey, the resulting shock wave can be enough to kill or stun the prey.
The snap can also produce sonoluminescence from the collapsing bubble. This will produce a very small amount of light and high temperatures in the range of several thousand kelvin within the collapsing bubble, although both the light and high temperatures are too weak and short-lived to be detected without advanced scientific equipment. The light emission and temperature increase probably have no biological significance but are rather side-effects of the rapid snapping motion. Pistol shrimp produce this effect in a very similar manner


lidt info fra youtube
youtube - en krabbe der får tæsk
en anden krabbe der får tæsk på youtube



wiki ->http://en.wikipedia.org/wiki/Mantis_shrimp
wiki ->http://en.wikipedia.org/wiki/Peacock_mantis_shrimp




Og så er der dens øjne som anses for at være de mest komplekse der findes:

Citat:
Mantis shrimp possess hyperspectral colour vision, allowing up to 12 colour channels extending in the ultraviolet[10]. Their eyes (both mounted on mobile stalks and constantly moving about independently of each other) are similarly variably coloured, and are considered to be the most complex eyes in the animal kingdom.[11][12] They permit both serial and parallel analysis of visual stimuli.
Each compound eye is made up of up to 10,000 separate ommatidia of the apposition type. Each eye consists of two flattened hemispheres separated by six parallel rows of highly specialised ommatidia, collectively called the midband, which divides the eye into three regions. This is a design which makes it possible for mantis shrimp to see objects with three different parts of the same eye. In other words, each individual eye possesses trinocular vision and depth perception. The upper and lower hemispheres are used primarily for recognition of forms and motion, not colour vision, like the eyes of many other crustaceans.
Rows 1-4 of the midband are specialised for colour vision, from ultra-violet to infra-red. The optical elements in these rows have eight different classes of visual pigments and the rhabdom is divided into three different pigmented layers (tiers), each adapted for different wavelengths. The three tiers in rows 2 and 3 are separated by colour filters (intrarhabdomal filters) that can be divided into four distinct classes, two classes in each row. It is organised like a sandwich; a tier, a colour filter of one class, a tier again, a colour filter of another class, and then a last tier. Rows 5-6 are segregated into different tiers too, but have only one class of visual pigment (a ninth class) and are specialised for polarisation vision. They can detect different planes of polarised light. A tenth class of visual pigment is found in the dorsal and ventral hemispheres of the eye.
The midband only covers a small area of about 5°–10° of the visual field at any given instant, but like in most crustaceans, the eyes are mounted on stalks. In mantis shrimps the movement of the stalked eye is unusually free, and can be driven in all possible axes, up to at least 70°, of movement by eight individual eyecup muscles divided into six functional groups. By using these muscles to scan the surroundings with the midband, they can add information about forms, shapes and landscape which cannot be detected by the upper and lower hemisphere of the eye. They can also track moving objects using large, rapid eye movements where the two eyes move independently. By combining different techniques, including saccadic movements, the midband can cover a very wide range of the visual field.
Some species have at least 16 different photoreceptor types, which are divided into four classes (their spectral sensitivity is further tuned by colour filters in the retinas), 12 of them for colour analysis in the different wavelengths (including four which are sensitive to ultraviolet light) and four of them for analysing polarised light. By comparison, humans have only four visual pigments, three dedicated to see colour. The visual information leaving the retina seems to be processed into numerous parallel data streams leading into the central nervous system, greatly reducing the analytical requirements at higher levels.
At least two species have been reported to be able to detect circular polarized light [13][14]. The species Gonodactylus smithii is the first - and only - organism known to simultaneously detect the four linear, and two circular, polarization components required for Stokes parameters, which yield a full description of polarization. It is thus believed to have optimal polarization vision [14][15][16][17].

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