Morphological Characteristics of Piranha, Clever Adaptations

[Just1nK4ng]

I'm going to use this thread to post some interesting morphological, or body, characteristics of the Red Bellied Piranha I have observed over the past 20 or so years of keeping these unique fish. Don't hesitate to add your own observations to this thread too.


Buccal Valve:

One of the easier things to see different about these fish and most others, besides the teeth , is the presence of a buccal valve. As piranha spend most of their time with their mouths open, only rarely closing them, breathing could pose a problem as oxygenated water, obviously, has to pass through the mouth over the gills. An open mouth will prevent this but these cleverly designed little fishes have this buccal valve that can easily be seen just by looking into their mouths.... careful of your nose!

This is a survival adaptation which becomes very apparent when the fish has a large morsel of food which it is carrying about before eating. I have seen my fish swim about with food for a little while before actually consuming it. Only then do the advantage of this valve become apparent. With a widely open mouth piranha can still breath as this valve allows water to enter the mouth and then closes behind it to force it through the gills. Clever fish.

 

[Just1nK4ng]

Hinged Jaws:

Don't know if anybody else mounted a skull of one of these fish but if you were to look at the jaws from behind there is a very rigid but flexible hinge in the center of the jaw much the same design as a piano hinge.

When feeding, watch the action of the jaws, if they don't eat too fast that is.... They can spread twice as wide as they look when the fish is relaxed. This is a pretty unique adaptation to these fish which may allow them to maximize their bite size. First impressions can be misleading. The fish appear not to have large mouths but a good yawn gives the large gape away.

The most obvious hint of this can be seen in the cheeks. When a big morsel is taken the cheeks puff out. This is the jaws widening on the hinge.

Anybody else take notice of this?

 

[Just1nK4ng]

Nasty-assed Teeth:

As you are well aware these fish have teeth. Why else would all us piranha freaks have them!! There are a number of incredible attributes to these teeth that serve these fish well.

First of all, sharpness can't be underestimated. They are needle tipped with razor sharp edges even after the fish are finished and shed them. Shedding occurs about every two months in stages. They can't afford to go about with a mouth full of no teeth so they have a strategy. They shed a quarter of the mouth at a time.

New teeth are made in the jaw, much like our own and unlike sharks, and when they are ready they just rise, pushing the "old" ones out all at once (per quadrant) and within one to two days the new ones are in place and set strongly. Couple of weeks later another quadrant, usually the ones opposite the new ones, do the same. This will continue for about a month until all teeth are in place again.

This ensures the fish will always have 3/4 of it's teeth remain for defense and feeding.... a necessity when all your neighbours are well armed.

The teeth themselves are set such that there is a little cusp at the back of each upon which the rear teeth sit firmly upon. Not only does this produce a solid cutting surface without any gaps between the teeth but it causes the teeth to become very strong. If one of the rear teeth encounter bone, the force is shared with the teeth in front to prevent breakage or loss. If a tip is broken it stays that way until shedding of the entire set occurs.

The two front teeth of the lower jaw aren't connected to each other but are very close such that when the hinged jaw opens they stay together.

The bottom teeth are about three times larger than the top ones and, when the mouth is closed, sit behind the top much like an overbite. They don't, as many books on the subject say, fit between the gaps in the top teeth. The top teeth only act to hold the prey while the bottom ones slice. This is very effective for quick feeding as a long channel of meat can be cleaved off and swallowed simultaneously. The top teeth grip and the cleavers slice, the top teeth shifted further up and the slicing continued. This allows for very rapid removal of meat from a large animal... let's say a bloody cow! ............. Small round bites aren't what skins a cow but the stripping off of the meat.................. mmmmmmmmmmm ..............Small morsels like feeder fish or mice are just bitten into.

Incidently, if one was to hold an 11 inch Great White Shark in their hands, it wouldn't be a problem reaching in and touching the teeth. No offence to the mighty shark but there's no comparison as a full thumb would be snipped off in a heartbeat if it was tried with our little snappers.

 

[Just1nK4ng]

Rigid Skull:

Most fish when dissected have many loose bones which make up the skull, even the powerful jawed wolffish which eat clams, snails, lobster, sea urchins.... When the flesh is removed the bones come apart like a puzzle.

Piranhas have a skull that is completely rigid and almost look like a freaked out humanoid with goth teeth :laugh:

Seems the strength of the jaw muscles are powerful enuf to warrant a solid mass of fused bones. There's also a pocket on either side where the large cheek muscles sit. These muscles are huge compared to other fish and are attached to the jaw further to the front to maximize biting power.

The jaw itself is very rigid and solid for it's size. There's nothing to compare the jaw with as no other fish comes close to it's thickness and strength for it's size. The joint where it attaches to the skull is remarkable as well.

These fish are full of unique adaptations

Note: This image has been copied from an avatar on this site. I can't remember who I got it from but if you recognize it please let me know so I can put your name as the source.

 

[jenBLKAROWANA]

Wow...fasinating info! Thank you!!! I never knew that about those nasty little buggers!

Jen

 

[piranha45]

I learned some stuff there....

 

[Just1nK4ng]

Thanx guys

As a fish biologist I have been interested in these marvels of adaption piranha have and where else to discuss this stuff than with a bunch of other like-minded individuals who are equally amazed with these small deadly finned animals.

 

[Just1nK4ng]

T-Beam Ribs:

As is very apparent piranha of all species share a flat body shape much like a discus fish... with some variation. Why not just have an elongated torpedo shape instead? .. Ahhh.. these fish have a method to their madness....

For starters, watch two fight. They start by doing their threating displays to each other by puffing out the fins, gaping their jaws, and waving their bodies back and forth. The next step is to put up or leave the area. Those that continue the fight will try and take a bite out of each other. This seems to be impossible to do if the fish are attacked on the side and I have witnessed this many times. The teeth can't get a grip. They will also do their best to protect their top and bottom and will always turn their flat side to each other to avoid showing any area vulnerable to a bite. I have seen fish slash repeatedly at each other and as long as it's at the flat side, it does no harm.

When schooling, opportunities for sucker bites from other piranha abound but as long as the other fish don't try and get above, or under the target, they are safe from each other.

Eating any type of fish one occassionally comes across small bones which are thin and roundish in cross-section. Piranha, on the other hand, have strong, solid ribs which, if taken in cross-section, are like T-beams. This lends tremendous strength to them preventing bending during an attempted bite. Bending would allow the teeth to get hold of the side and would be sure to cause a fatal wound.

Fish that do receive a bite from above, below, or of the tail area quickly give up the fight and flee for their lives.... or disappear within seconds like so much other feeder foods .

 

[jenBLKAROWANA]

Amazing creatures....You just keep spilling out info! I love it!!!!

Jen

 

[Just1nK4ng]

Glad you are enjoying this stuff.... these fish are just plain FASCINATING!!!!

go second page for more info on these fishs