Uploaded April 2026 | Updated September 2026, 2 weeks ago
From ninety-tonne supercarnivores to grass-eating dwarfs to land-walking goofballs, sharks have done it all. These animals were revered across human history as sleek killing machines, perfectly adapted for a life as apex predators of the vast ocean. Just as with crocodiles, however, the idea that sharks are “living fossils” that haven’t changed since the time of the nonavian dinosaurs is a false one. Sharks, and the larger group of elasmobranchs that they belong to, are incredibly diverse and have expanded to occupy a huge variety of different ecological positions over the last three hundred million years. Let’s talk about the elasmobranchs on a broad scale, discussing some of their most iconic groups as well as the physiological traits that contribute to their legendary success.
00:00: Why Sharks Are Nature's Favorite Animals
01:00: What Are Elasmobranchs?
01:44: Holocephalians
03:16: Symmoriiformes and Ctenacanthiformes
04:50: Xenacanthiformes and Phoebodontiformes
05:44: Hybodontiformes
06:44: Batoidea
07:53: Squaliformes
09:30: Hexanchiformes
10:13: Squatiniformes and Pristiophoriformes
10:55: Heterodontiformes and Orolectolobiformes
12:25: Lamniformes
16:48: Carcharhiniformes
18:54: Ampullae of Lorenzini
Thumbnail art by Rudolf Hima; Mark Witton; Mario Lanzas
From ninety-tonne supercarnivores to grass-eating dwarfs to land-walking goofballs, sharks have done it all. These animals were revered across human history as sleek killing machines, perfectly adapted for a life as apex predators of the vast ocean. Just as with crocodiles, however, the idea that sharks are “living fossils” that haven’t changed since the time of the nonavian dinosaurs is a false one. Sharks, and the larger group of elasmobranchs that they belong to, are incredibly diverse and have expanded to occupy a huge variety of different ecological positions over the last three hundred million years. Let’s talk about the elasmobranchs on a broad scale, discussing some of their most iconic groups as well as the physiological traits that contribute to their legendary success.
00:00: Why Sharks Are Nature's Favorite Animals
01:00: What Are Elasmobranchs?
01:44: Holocephalians
03:16: Symmoriiformes and Ctenacanthiformes
04:50: Xenacanthiformes and Phoebodontiformes
05:44: Hybodontiformes
06:44: Batoidea
07:53: Squaliformes
09:30: Hexanchiformes
10:13: Squatiniformes and Pristiophoriformes
10:55: Heterodontiformes and Orolectolobiformes
12:25: Lamniformes
16:48: Carcharhiniformes
18:54: Ampullae of Lorenzini
Thumbnail art by Rudolf Hima; Mark Witton; Mario Lanzas
