When people think of sharks, they think of the majestic White (Carcharodon carcharias), the sleek Blue (Prionace glauca), or the fast Shortfin mako (Isurus oxyrinchus).
White shark; photo credit: Raul Touzon
What is a Ray?
However, many people do not know that sharks have other relatives. Elasmobranchs refers to fishes that have a cartilaginous skeleton, no swim bladders, and have five to seven gill slits. We will be focusing on the batoids, aka ‘flatsharks’. People might be familiar with the word ‘ray’, but what defines a ray? A ray is a flattened shark, with the gill slits only visible on the ventral side. Currently, there are six orders of elasmobranchs taxanomists have defined as batoids. They include: Pristiformes (Sawfishes), Rhiniformes (Wedgefishes), Rhinobatiformes (Guitarfishes), Torpediniformes (Electric Rays), Myliobatiformes (Stingrays), and the Rajiformes (Skates).
Here are what some of these batoids look like:
Dwarf sawfish (Pristis clavata)
Black Spotted Torpedo Ray (Torpedo fuscomaculata)
Shovelnose guitarfish (Rhinobatos productus)
Bowmouth guitarfish (Rhina ancylostoma)
Smoothnose wedgefish (Rhynchobatus laevis)
As you can see even these flat sharks are variable in morphology! If you are interested in how these orders are related in-depth, please check out the Tree of Life! We will go through all these different orders at a later time, but let’s focus on two orders: Myliobatiformes (Stingrays), and the Rajiformes (Skates). People often confuse these two groups, since they have similar body plans, but let’s take a closer look at their differences.