Cephalochordata

Three Characteristics:

1. They are marine
2. They all have segmented bodies
3. They all have elongated bodies

Two Common Names:

1. Lancelet
2. Amphioxus

Poem:
My size is rather small never longer than inches of four or five,
my circulatory system is closed like feelings insinde my heart.
The ocean is unending amd my existence is small,
the cuts in my heart are like the segments of my body,
small but plentiful.
So I will continue to swim with the pulse of my notochord,
and the beating of my will.