---
title: Sharks (Selachimorpha)
scientific_name: Selachimorpha
common_name: Sharks
rank: Superorder
published: 2024-11-19T18:41:51.573Z
updated: 2026-08-23T20:40:37.909Z
tags: Sharks, Selachimorpha, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/fishes/sharks
---

# Sharks (*Selachimorpha*)

## Quick facts

- **Rank:** Superorder
- **Scientific name:** Selachimorpha
- **Body shape:** Torpedo - Streamlined and muscular, built for open-water speed - jacks, tunas, barracudas.
- **Subcategories:** 7

## How to recognise this group

- elongated, muscular body, typically tapering towards the tail
- five to seven distinct gill slits on each side of the head
- paired pectoral fins clearly separate from the head
- caudal fin with upper lobe visibly longer than lower lobe
- mouth positioned on the underside of the head

A shark has no bones. The entire skeleton is cartilage, the same material as the tip of your nose, which is lighter than bone and flexible enough that a shark can turn inside its own body length. It is also why the fossil record of sharks is almost entirely teeth: cartilage rots, enamel does not.

It has no swim bladder either. Every bony fish carries a gas-filled bag it inflates and deflates to hold depth without effort; a shark does not have one, and instead carries an enormous liver, up to a third of its body weight, filled with low-density oil. That gets it most of the way to neutral, and the rest comes from swimming. Many sharks must keep moving to stay off the bottom, and some must keep moving to breathe at all, forcing water over the gills by driving forward.

The skin is made of teeth. Under a lens, a shark's hide is covered in millions of tiny tooth-shaped scales called denticles, with the same enamel, dentine and pulp as the teeth in its mouth, all pointing backward. Stroked from head to tail it feels smooth; the other way it will take skin off your hand. The denticles also break up turbulence, and the shape has been copied into swimsuit fabric and aircraft skin. The teeth themselves sit in rows on a conveyor: as one is lost the next rotates forward, and a shark can go through tens of thousands in a lifetime.

And they read electricity. The snout is dotted with jelly-filled pores, the ampullae of Lorenzini, that detect fields down to a few billionths of a volt per centimeter, which is enough to find a fish buried in sand by the electrical activity of its own heartbeat. Nothing hides from that.

Sharks have been doing this for over four hundred million years, which means they are older than trees. About thirty species live in this sea, from meter-long reef sharks to the whale shark, and most of them are far more wary of you than the reverse.


## Subcategories

- [Hammerhead sharks (Sphyrnidae)](https://redseacreatures.com/taxon/fishes/sharks/hammerhead-sharks)
- [Mackerel sharks (Lamnidae)](https://redseacreatures.com/taxon/fishes/sharks/mackerel-sharks)
- [Nurse sharks (Ginglymostomatidae)](https://redseacreatures.com/taxon/fishes/sharks/nurse-sharks)
- [Requiem shark (Carcharhinidae)](https://redseacreatures.com/taxon/fishes/sharks/requiem-shark)
- [Thresher sharks (Alopiidae)](https://redseacreatures.com/taxon/fishes/sharks/thresher-sharks)
- [Whale sharks (Rhincodontidae)](https://redseacreatures.com/taxon/fishes/sharks/whale-sharks)
- [Zebra sharks (Stegostomatidae)](https://redseacreatures.com/taxon/fishes/sharks/zebra-sharks)

---

*Source: [Red Sea Creatures](https://redseacreatures.com/taxon/fishes/sharks)*
*Updated: August 23, 2026*