Uncover the similarities and differences that set sharks and rays apart. <\/p>
Sharks and rays are from the same family known as elasmobranchs and there are over 1,100\u00a0known species of\u00a0elasmobranchs in our oceans. That\u2019s over 500 sharks,\u00a0and over 600 rays, say the experts at The Shark Trust<\/a>.<\/strong><\/p> Elasmobranchs are a subclass of\u00a0\u2018Chondrichthyes\u2019\u00a0\u00a0and\u00a0have cartilaginous, rather than bony,\u00a0skeletons. They exhibit\u00a0a\u00a0vast\u00a0diversity of shapes, sizes and adaptations, unique to each species.\u00a0<\/p> Here, we unravel the differences\u00a0between\u00a0the\u00a0sharks and\u00a0the\u00a0rays, and how\u00a0to\u00a0tell them apart.<\/p> From an evolutionary perspective,\u00a0the\u00a0sharks came first, having been around for\u00a0over 400\u00a0million years. Rays\u00a0diverged from them only around 200 million years ago.\u00a0<\/p> It is believed that rays evolved from sharks that had adapted well to the sandy, muddy sediments of shallow\u00a0coastal\u00a0slopes\u00a0during the Jurassic Period. Their bodies flattened out, their pectoral fins became enlarged and in many of them, the tail area was reduced. <\/p> Some (mobulids\u00a0and mantas) developed cephalic lobes (fleshy projections on the side of their heads), covered in\u00a0electrosensory\u00a0pores to help when hunting.\u00a0Others developed a sting in their tail;\u00a0their modified tails having become superfluous to movement evolved into a defence mechanism, while some adapted to fresh water, living in rivers and lakes around the world.<\/p> When comparing most species of sharks and rays, the most pronounced difference is usually the\u00a0torpedo\u00a0or\u00a0flat shape\u00a0of their bodies. However, this distinction can become misleading when, for instance, comparing Angel Sharks<\/a> and Guitarfish. <\/p> Both are flat-bodied species, but one is a shark and the other a ray. One key, reliable difference between sharks and rays is the gill placement: among rays, the gills are located on the underside of the body, whilst in sharks they are located on either side of their head.<\/p> The evolution of\u00a0the\u00a0flattened, disc-like bodies\u00a0of rays\u00a0has engendered many other \u00a0advantageous \u00a0adaptations, which separate them from sharks:<\/p> Many species of sharks are known as \u2018ram ventilators\u2019, meaning they\u00a0have to\u00a0keep moving in order to get oxygen through their gills. All rays have evolved special organs called \u2018spiracles\u2019 which allow them to flush water through their gills<\/a> even when buried under the sand,\u00a0in order to\u00a0continuously receive oxygen when stationary or covered up.<\/p> All sharks swim using continuous side to side undulations their body. This creates the classic swimming motion that we know as they glide forward through the water column.<\/p> In contrast, most rays use one of two movement options, undulatory or oscillatory movement. Undulatory swimmers pass short waves down the pectoral fins. In contrast, oscillatory\u00a0swimmers\u00a0\u2018flap\u2019 their pectoral fins to push themselves forward, similar to a bird wing flapping.<\/p> There is often some confusion around skates and rays, so\u00a0whilst we\u2019re on the topic of differences,\u00a0we thought we\u2019d clear this up too.\u00a0<\/p> Put simply, all skates are rays but not all rays are skates. In other words, rays are the umbrella for many species and\u00a0families\u00a0of rays \u2013 one of which are the skates.\u00a0<\/p>Which came first, the shark or the ray?<\/h2>
What’s the difference between sharks and rays?<\/h2>
How do sharks and rays ‘breathe’?<\/h2>
How do sharks and rays swim through the water?<\/h2>
What about rays\u00a0and\u00a0skates – what’s the difference between them?<\/h2>