phylum chordata
DESCRIPTION
Phylum Chordata. SBI 3U. What are Chordates?. Chordates are animals with a nerve cord, notochord and gill slits (at least at some point in their lives). Characteristics of Chordates. Bilaterally symmetrical Ventral heart Body extends past anus into a tail Nerve cord Notochord - PowerPoint PPT PresentationTRANSCRIPT
Phylum Chordata
SBI 3U
What are Chordates? Chordates are animals with a nerve cord,
notochord and gill slits (at least at some point in their lives)
Characteristics of Chordates Bilaterally symmetrical Ventral heart Body extends past anus into a tail Nerve cord Notochord Gill slits
More about chordates Most recent group of animals Make up only about 5% of animal species
What is a nerve cord? Unique to chordates Dorsal nerve cord (dorsal=back side) Found in the embryos of animals within the
phylum chordata NOT the spinal cord but it develops into one
in vertebrates Part of the nervous system Connects the brain with the lateral muscles and other organs
What is a notochord? A notochord is a skeletal rod made up of
cartilage Found in all embryonic and some adult
chordates In vertebrates only present during
embryonic development
Classification of Chordates Three subphyla: Cephalochordata, Urochordata and
Vertebrata Cephalochordata: such as lancelets Urochordata: such as tunicates Vertebrata: such as amphibians, reptiles, birds and
mammals
Cephalochorata & Urochordata Filter-feeding marine organisms Filter-feeding pass water over a specialized filtering
structure Have notochords No backbones or vertebral columns Transition from invertebrates chordates Example: Lancelet (cephalochordata) Example: Tunicate
Vertebrata Approx. 95% of all chordates Presence of vertebrae hollow, cartilaginous, bony structure
protects dorsal nerve cord Endoskeleton Large brain protected by skull Advanced nervous system Circulatory system Large coelom containing vital organs
Development of Appendages Two pairs of appendages limbs Improvement of locomotion One of the defining features of vertebrates Even snakes have them!
Skull Anterior skull with a large brain Supports structures of the face and protects
brain
Mouse Human Dog
Circulatory System Ventral heart pumps blood throughout body
in the process, delivering oxygen throughout