Why do fish have vertical tail fins and whales have horizontal ones?

Thursday 24th September 2009
Uploaded by: Yan Wong
Asked by: Rich Webb, Northampton

It reflects the evolutionary history of locomotion. Our wormy ancestors slithered on the sea floor, so undulated side-to-side. Fish inherited that movement, for which a vertical tail is best.

Their distant land mammal descendants evolved to run with limbs underneath: an unstable gait allowing rapid direction changes. To extend the stride, their spine flexes up-and-down. Marine mammals kept this movement, for which a horizontal tail is best.

What's the fastest speed a human has ever experienced?
previous Q&A Article
What’s the furthest south the Northern Lights have been seen?
next Q&A Article
Q&A Tabs

QWERTY came about because the keys on early typewriters used to stick, especially if frequently used letters were placed close to each other. American inventor Christopher Latham Sholes had the...

The deepest mine in the world is Mponeng, part of the West Wits gold field, in the North-West province of South Africa. Mponeng has been gradually deepened over its lifetime and is now 3.9km (2.5...

At the manufacturing stage, when juice from oranges has been extracted and the pulp removed, the product is processed into two forms: not-from-concentrate (NFC) or bulk frozen concentrated orange...

A sneeze begins with a sudden inhalation. This is the ‘Aaah’ part of the sneeze. The ‘Choo!’ occurs on the exhale because most of the muscles in your body are reflexively...

All female mammals have a clitoris, the sole purpose of which is to react to sexual stimulation, and presumably this stimulation has evolved to be pleasurable for most species. But establishing...

To create a sound, we have to set matter - whether it's a gas like air, a liquid or even a solid material - in regular motion, creating a wave of specific frequencies, which we hear as a sound of...

Mirrors don’t reverse left and right either – that’s just our interpretation of what happens. Your reflection in the mirror is actually reversed front to back – if you have...

Discovered by an American student named Gary Flandro in the mid-1960s, the slingshot manoeuvre usually involves spacecraft briefly 'coat-tailing' a planet orbiting the Sun, extracting some of the...

The ice disappears because the wind blows away water molecules that have evaporated or 'sublimed' from the ice, so the ice slowly shrinks in size. The molecules that escape are those with the...

We use cookies to improve your experience of our website. Cookies perform functions like recognising you each time you visit and delivering advertising messages that are relevant to you. Read more here