(II)Cephalochordata- Branchiostoma (Amphioxus or Lancelet).
Characteristics of Vertebrate:
Vertebrates include animals which possess vertebral column and a cranium.
They possess a well-developed brain follows by a spinal cord in the vertebral column.
They bear two pairs of appendages, three pairs of sense organs.
Aquatic vertebrates have gills and terrestrial forms have lungs for respiration.
The heart is located on the ventral side.
The skin is separable from the visceral organs and the skeleton is internal.
The liver and pancreas are well developed.
Examples- Lizards, Frog and birds etc.
“All vertebrates are chordates but all chordates are not vertebrates”. Justify the statement?
All the vertebrates are chordates because they have all those characteristics which are essentially fundamental features of chordates like the presence of a notochord, a dorsal hollow nerve chord and paired pharyngeal gill slits. But all the chordates cannot be vertebrates as some chordates like Protochordates do not have cranium or brain box. In Urochordates, the notochord is restricted to the tail region in the larval stage and get lost in the adults.