SHARK TAXONOMY
Basking Shark © Charles Hood.

Taxonomy is the scientific field concerned with the classification and naming of species, it forms the bedrock for our understanding of (in our case) sharks, skates, rays and chimaera.

It’s vital to know what species are and how they’re related, in order to better understand their function within the ecosystem.

Up until the 1600’s each animal and plant were referred to by their common names, but these vary even within the same language - in English the Basking Shark has been referred to as Bone Shark and Elephant Shark. These names vary again in different languages - in French it’s Pélérin or Éléphant de Mer, in Spanish Peregrino, in Portuguese Albafar and in Italian lo Squalo Elefante. This system of naming species understandably caused some confusion and made it difficult for scientists speaking different languages to discuss species.

In the 1600’s, a Swedish scientist called Carl Linneaus invented a system that created order from chaos. Although this system has altered over time, the concept has remained the same and is still used today.

Below is a simple introduction to taxonomy, however this system is much more complex and includes intermediate classification ranks such as Super-class, Super-order, Sub-order and Super-families, housed in between these levels.


KINGDOM - Organisms are grouped together under very wide categories, such as Animalia (Animal) or Plantae (Plant). Sharks belong to the Kingdom Animalia.


PHYLUM - This level divides the Kingdoms into smaller groups that share similar characteristics. Sharks belong to the Phylum Chordata and the Sub-phylum Vertebrata, as they possess a spinal chord, notochord and a backbone (vertebrae).


CLASS - These groups include the more familiar Aves (Birds), Mammalia, Reptila and Amphibia. Sharks belong to the Class Chondrichthyes, which include fish that have a cartilaginous skeleton. They are further divided into two Sub-classes; Elasmobranchii (sharks, skates and rays) and Holocephali (chimaera).


ORDER - Further identification of similar looking animals and plants starts to get more complicated. The Elasmobranchii are divided into two super-orders, the extinct Cladoselachimorpha and the Euselachii, which is made up of 12 Orders. Only nine Orders of Euselachii exist today:

Blonde Ray © Sally Sharrock.

Skates and Rays (Rajiformes) - are generally flattened in shape because of their enlarged pectoral fins (or wings). Five pairs of gill slits are on the underside of the body rather than on the side as with sharks.

Japanese Sawshark © Ume-y-(cc-by-2_0).

Sawsharks (Pristiophoriformes) - have a long saw-like snout, which they use to stun prey and defend themselves against predators. They have either five or six pairs of gills.

Angelshark © Simon Rogerson.

Angelsharks (Squatiniformes) - with a flattened body these sharks may look more like rays, but their gills are positioned on the side of their body.

Spiny Dogfish © Lill Haugen.

Dogfish Sharks (Squaliformes) - have a short mouth with a long snout and five pairs of gills.

Sevengill Shark © Peter de Maagt.

Sixgilled Sharks (Hexanchiformes) - as the name suggests these sharks have six pairs of gills, however to add confusion some have seven pairs (unlike most other sharks which have five).

White Shark © Sean Sequeira.

Mackerel Sharks (Lamniformes) - have a long snout and mouth, with five pairs of gills. This order includes the infamous White Shark, the filter feeding Basking Shark, and the Shortfin Mako Shark that can reach speeds of 30mph.

Hammerhead Shark © Jillian Morris.

Ground Sharks (Carcharhiniformes) - have a wide mouth with sharp-edged teeth and five pairs of gills. They also have a moveable membrane over their eyes to protect them when they are feeding. Reef sharks and the flat headed hammerheads belong to this Order.

Wobbegong © Andy Murch.

Carpetsharks (Orectolobiformes) - have a short snout and five pairs of gills. Most have barbels near their mouth, which they use to taste food under the seabed. This Order includes wobbegongs, blind sharks and the enormous Whale Shark.

Port Jackson © Taso Viglas, Wikimedia Commons.

Bullhead Sharks (Heterodontiformes) - have five pairs of gills and fin spines on their dorsal and anal fins. Port Jackson Sharks belong to this Order.


FAMILY - These groups include species that are closely related. For example apes, monkeys and humans belong to the Family Primates. Some Families are extremely large while others contain just a few members.


GENUS - The Genus (first word of the scientific name) shows just how closely related species are to each other. For example, the Shortfin Mako Shark is Isurus oxyrinchus and the Longfin Mako Shark is Isurus paucus – Isurus is the Genus and shows us they are closely related.


SPECIES - A species is a group of organisms (animal or plant) that are capable of interbreeding and producing fertile offspring. The first part of a species name refers to the Genus (and begins with a capital letter) and the second part (written in lower case) completes the species name, which is either italicised or underlined, e.g., Carcharodon carcharias – the White Shark.


Angelshark © Simon Rogerson.An example of a taxonomic hierarchy is:

Kingdom: Animalia
Phylum: Chordata
Class: Chrondrichthyes
Order: Squatiniformes
Family: Squatinidae
Genus: Squatina
Species: Squatina squatina (Angelshark)
 


FAMILY TREE FOR BRITISH SHARKS:

British Sharks Family Tree (pdf)
 


RELATED LINKS:

➤ Download our British Sharks Family Tree (pdf)

➤ Download our British Skates and Rays Family Tree (pdf)