Inferior mesenteric artery
The part of the colon located distal to the left colic flexure is derived from the hindgut is supplied by the inferior mesenteric artery. The distal part (lower third of the rectum) is supplied by the internal iliac artery. The ileocolic artery supplying the cecum is a branch of the superior mesenteric artery.
Cytoplasm (glycolysis) and the mitochondria (cristae and matrix)
Hag Fish and Lamprey
Vertebrates are the organism which posses a vertibral column(aka the spine or back bone structure), while the earliest had a head they lacked a spine and jaw, these jawless vertebrae lived 500-600 million years ago. they are the ancestors of bony fish which in time became amphibians and other groups of animals