they saw a dragon flying
The scientific name for dragonflies is Odonata.
There are several Families of dragonflies. If you are looking for the commonly used general classification name for them, the Order name for dragonflies and damselflies is Odonata. The Suborder for dragonflies is Anisoptera. Odonata Central (http://www.odonatacentral.org) has lots of photos and classification information if you are looking for the Family name for a particular type of dragonfly.
The scientific name for the Blue dasher is Pachydiplax longipennis
yes dragoferosus
Dragonflies have too many predators to list. They're eaten by birds, bats, frogs, fish, large spiders, wasps and other dragonflies, to name a few.
Libellula lydia
yes
The scientific name for dragonflies is Order Odonata.
Odonata is the name of the order of dragonflies. It merges as members insects of the Anisoptera suborder of dragonflies and the Zygoptera suborder of damselflies. The name of the order traces its origins back to the ancient Greek οδόντoς (οδούς, odontos) for "tooth" even though damselflies and dragonflies are not unique in claiming toothed mandibles.
Dragonflies do not emit light. The insect that you are thinking of is a firefly, or the scientific name is Lampyridae, which are a class of beetles. They are nicknamed 'lightning bugs' in the US.
Dragonflies are invertebrates
The ancestors to the dragonflies was the Protondonata. These were the 1st winged insects on Earth and the earliest form of dragonflies.