Invertebrates
Invertebrates lack a hollow dorsal nerve cord. Even if they have a brain and a nerve cord running from it, that nerve cord does not run through a hollow tube along the back.
The number of species of invertebrates far outnumbers those which are chordates, and for every chordate on the planet there are over one million invertebrates!
Invertebrates can be very simple organisms, or can be complex and even show a degree of intelligence. There are eight major phyla of invertebrates.
Because they lack the skeletal structure of vertebrates, invertebrates often have a shell or tough covering, called an exoskeleton.
Does your animal have an exoskeleton, jointed appendages, and a segmented body?
