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9 Fascinating Facts about the Freshwater Stingray

freshwater stingrays facts

Freshwater stingrays facts

So to kick off – first the biology lesson.  Did you know that stingrays are members of the Elasmobranch class?  Well of course you did right? Just in case you didn’t..its is a group the includes both freshwater and marine stingrays, sharks and sawfish.  So now you know that, here are my 9 fascinating freshwater stingrays facts to help you understand your fishy friend a little more and marvel at how unique they are

denticles
Dermal denticles as viewed through an electron microscope

Freshwater Stingrays Facts # 1

Stingrays and their cousins the shark are covered with placoid scales Also called dermal denticles.  

Its the denticles that give the texture of smooth sandpaper.  

Placoid scales can’t actually grow in size, instead more scales are added as the fish increases in size.

 

Freshwater Stingrays Facts # 2

The barb is actually a modified denticle. The stingray has the ability to grow and shed its barb usually about twice a year. And its not uncommon for a ray to be seen with two barbs whilst the new one is growing. Usually the larger barb that is closer to the tail tip is the one that will fall off (Don’t forget  barbs can be found in your aquarium so please take care when removing them as they can still sting you even when they are no longer attached)

Freshwater Stingray Top Tip: If the barb is still black you can be sure that there is still a poisonous coating that you really don’t want to touch.

Freshwater Stingrays Facts #3

All Elasmobranchs shed their teeth continually thoroughout their life span.  Just take a look at the bottom of your tank if you don’t believe me. No, its not sand! Its teeth!

Freshwater Stingrays Facts # 4

Freshwater stingrays don’t have calcified bones instead their body is composed of cartilage – this enables the ray to maximise its movement. So it’s important to remember that great care should be taken when removing a ray from the water environment.

Freshwater Stingray Top Tip:  Moving rays should be done quickly with minimum stress to the fish.  The weight of the body can cause the cartilage to compress putting strain on the vital organs.

Freshwater Stingrays Facts # 5

Freshwater stingrays have adapted to living partially buried in the substrate. They rays have an accessory respiratory opening, the Spiracle. This is believed to be an adapted gill slit which has over time migrated to the dorsal side of the stingray. When the stingray is resting on the bottom and the under belly gills cannot allow water to pass through them then these spiricals open which allows the ray to breath whilst resting on the bottom.

Freshwater Stingrays Facts # 6

Stingrays have good eyesight which is a bonus for any ambush predator. Inside the eye there is a structure called the Operculum pupillare which controls the amount of light entering the eye. In dim light this will retract allowing greater light in and better vision at night.  So this is my favourite freshwater stingray fact.  Yes, they are watching you

Freshwater Stingrays Facts # 7

The digestive system of stingrays have evolved an unusual structure in the intestine. There are many layers or folds that have been added to the lining of the intestine. As food passes through the digestive tract it passes through this spiral valve. This explains why stingray waste has a ribbon like twist to it. This adaptation is also found in sharks and other primitive fish.

Freshwater Stingrays Facts # 8

The barb of the freshwater stingray is located midway along the tail of the ray. It is a defence weapon. The barb is only used a defence strategy and never used to hunt with. The ray is able to swipe its tail and reach its furthest point of its body in a very quick response. Want to know more about the venom and the spine read my other blog on the topic

Freshwater Stingrays Facts # 9

Potamotrygon is a genus of freshwater stingrays native to the rivers of South America. There are currently 27 recognized species in this genus.  So plenty of stingrays for us to put on our wish list

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