A few key traits distinguish chordates from other animals: the notochord, the dorsal nerve cord, pharyngeal slits, and the post anal tail. In many chordates, some of the these features disappear as the animal develops, or they morph into other useful body parts. Crash Course has a great summary of how we got from Lancelets to humans. https://www.youtube.com/watch?v=F8aVgSIDJjM
One of the earliest chordates, the Hagfish, is capable of producing a mind bending quantity of slime almost instantly. Here is a video of hagfish in New Zealand using the slime for defense. The US Navy is researching how a synthetic version of hagfish slime might be used to protect warships.
One of the earliest chordates, the Hagfish, is capable of producing a mind bending quantity of slime almost instantly. Here is a video of hagfish in New Zealand using the slime for defense. The US Navy is researching how a synthetic version of hagfish slime might be used to protect warships.