One of the most important fins on a fish is the tail fin, which is called the caudal fin.

Caudal fins – or fish tails – can be many different shapes. The main shapes are rounded, square, forked and lunate.

Here are four main caudal fin (fish tail) shapes:

 

Rounded tail: Sometimes this is called a paddle tail. Eels have rounded tails.

 

Square, truncated or emarginated tail: This is a short tail that ends with a straight edge, almost like a triangle. Some salmon have a square tail. Emarginated tails have a slight inward curve.

 

Forked tail: A forked tail is split into two prongs, or two distinct parts. Tuna have deeply forked tails.

 

Lunate tail: Lunate tails are shaped like a crescent moon. Mako sharks and basking sharks have lunate tails.

 

 

Photographer: Martina Nicolls

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