Advanced Features of Vertebrates over Protochordates PDF

ADVANCED FEATURES OF VERTEBRATES OVER PROTOCHORDATES : Vertebrates have several advanced features over protochordates, including: Vertebral column: Vertebrates have a vertebral column, or backbone, made up of vertebrae separated by discs. The notochord of protochordates is either replace...

ADVANCED FEATURES OF VERTEBRATES OVER PROTOCHORDATES : Vertebrates have several advanced features over protochordates, including: Vertebral column: Vertebrates have a vertebral column, or backbone, made up of vertebrae separated by discs. The notochord of protochordates is either replaced by the vertebral column or persists alongside it. Brain: Vertebrates have a brain as part of their central nervous system. Heart: Vertebrates have a chambered heart with red blood cells (RBCs) in the blood. Sexes: Vertebrates have separate sexes, except for some fish. Fertilization: During fertilization, the sperm and ovum unite in the animal pole pathway. Examples: Agnathan to mammals. Neural crest cells: Vertebrates have neural crest cells that develop into the nervous system. Endostyle: The endostyle is absent in adult vertebrates, but is present in the larval stage of some vertebrates. Other features of vertebrates include: A cranium or skull to protect the brain A muscular system attached to the endoskeleton for movement A closed circulatory system Skin that may produce scales, feathers, fur, or hair Paired kidneys for excretion Glands throughout the body for the endocrine system Protochordates are primitive chordates without head and vertebral column. Some primitive features of protochordates are as follows: Notochord persists throughout life. No cranium or vertebral column. Atrium, the space in between the pharynx and body wall, is present. Endostyle is present except hemichordates. It is the precursor of the thyroid gland of higher vertebrates. Absence of neural crest cells in the development of the nervous system. Pharyngeal slits or clefts are present throughout life. Hearts chamber less. No blood corpuscles in the blood. Sexes mostly separate (dioecious), or monoecious in most urochordates. During fertilization, the sperm unites with the ovum in the pathway of the vegetal pole. Examples: Hemichordates, urochordates and cephalochordates.