The evolution of flight (Part 1)

Many animals are able to fly and most of these are insects. However, when one stops to consider which vertebrates fly (vertebrates are animals with an internal skeleton including a spine and something resembling a spinal chord) only 3 main groups are able to fly.

These are: birds, Pterosaurs and bats.

The wing surface formed in 3 different ways one for each of these groups (see above).

Both bats and Pterosaurs used a wing-surface created by finger elongation (the 'pinkie' in Pterosaurs and all fingers elongated except the 'thumb' in bats).

Meanwhile, birds fly using a surface created by modified scales (feathers) and a strong series of arm and finger bones that are the result numerous bones fusing. Additional details are left out for brevity but are extremely interesting such as skeletal lightening in birds.

Pterosaurs are extinct and so only two extant flying vertebrate groups (extant = animals that are still alive today) are bats and birds. (What is a Pterosaur? Click here!)

Why did flight evolve?

There are two main thoughts about this. Basically either animals were able to flap and lift UP to escape predators etc. OR they were living in trees and started to glide from tree to tree (like 'flying' squirrels) also to catch food (insects) or avoid predators.

Regardless, the sky is (and was) full of potential food and once they were able to fly bats quickly filled a new niche (a niche is the ecological role of an animal generally relating to the food it eats). Both bats and birds were able to eat flying insects but bats as nocturnal animals compete with a fewer set of birds. Indeed this successful niche 'nocturnal insectivore' has since been radically expanded to include other more unusual food-types such as frogs or fish!

You can read more about the evolution of flight here.

Click here for cool videos of bats flying in slow motion.

For my next I will try to summarize the physics required for flight.