What do sharks and rays have in common?
If you thought that sharks and rays were similar, you are right. Sharks and rays have many things in common. But what are the similarities between sharks and rays? Let’s take a look…
What are the main similarities between sharks and rays?
- They are both cartilaginous fish meaning they have cartilage for skeletons instead of bones.
- Both have gill slits or clefts.
- They don’t have swim bladders.
- Both have dermal denticles or modified “scales” (shagreen) covering their skin.
- Both have ampullae of Lorenzini sensory organs or electroreceptors.
If you want to find more similarities between sharks and rays, please read on.
What are the similarities between sharks and rays in more detail?
In reality, a ray is quite simply a flattened shark. There are many similarities between sharks and rays, so lets go through them.
What sharks and rays have in common:
- Both are Chondrichthyes, which contains the class of fish elasmobranchs. Which is a subclass of fishes and means they have cartilaginous skeletons. This means sharks and rays don’t have bones.
- Sharks and rays use gill slits or clefts to breath underwater and have between five and seven pairs of slits.
- Unlike bony fish, sharks and rays don’t have swim bladders for buoyancy control.
- Sharks and rays are able to easily move between significant depths, which is because they don’t have swim bladders to restrict them like bony fish.
- The diet of sharks and rays make them both carnivores.
- The eyes of sharks and rays are found on their dorsal surface.
- The skin on sharks and rays is the similar. it is referred to as shagreen and is like rough sandpaper. This is due to the dermal denticles, which are modified “scales” that cover sharks and rays skin.
- Sharks and rays are both widely distributed across the globe. This includes the shallow coastal waters through to the deep and dark depths of the open ocean.
- Both sharks and rays are found in tropical seas, sub tropical, temperate waters and the cold waters of the Arctic and Antarctic regions.
- Sharks and rays are found in salt water and fresh water.
- Both sharks and rays have ampullae of Lorenzini which are special sensing organs or electroreceptors. These help sharks and rays to sense electric fields in the water.
- What gives sharks and rays their buoyancy instead of a swim bladder is a large liver filled with low-density oil.
- Male sharks and rays have claspers, which are located near their pelvic fin. These are what they use to mate with females.
- Female sharks and rays have a vent or genital opening called a cloaca. It is this organ where the male inserts his clasper into during fertilisation. The cloaca also serves for the elimination of urinary and faecal waste, as well as an aperture through which the young “pups” are born.
How are stingrays and sharks alike?
Stingrays are a type of ray. But them I’m sure this won’t be a surprise to you as ‘ray’ is in the name. Which means that stingrays belong to the same group of cartilaginous fish as all other rays and sharks.
The above list of similarities between sharks and rays are applicable to stingrays too. This means that instead of bones, stingrays have skeletons that consist entirely of cartilage.
They don’t have swim bladders like sharks either. They also use the same ampullae of Lorenzini sensors to sense the electrical signals emitted by their prey.
How do scientists classify sharks and rays?
It is this subclass of fish that is referred to as elasmobranchii which means sharks and rays have skeletons consisting of cartilage instead of bones.
Did rays evolve from sharks?
It is understood by scientists that sharks evolved around 450 million years ago. This means that sharks have survived at least four of the planet’s biggest extinction events in that time.
As a matter of interest it is the lobsters of the oceans that pre-date sharks in the evolution trail. Lobsters are thought to have prowled the oceans some 500 million years ago.
But the sub-species of sharks, i.e. rays, that many scientists believe originated from sharks around 170 million years ago during the Jurassic period.
This is about the same time the earliest snake fossils have been found dating back 140-167 million years. It is also around the time that Pangaea (or Pangea) split apart, which was 175 million years ago.
These primitive rays evolved to adapt to life on the seabed. They went from the torpedo like shape of the shark we know today, to the more flattened shape of rays.
The magnificent manta ray, which is a members of the genus Mobula, evolved roughly 20 million years ago.
I hope you enjoyed this article about similarities between sharks and rays
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