Phylum Chordata - Chicagoland Jewish High School
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Transcript Phylum Chordata - Chicagoland Jewish High School
Phylum Chordata
Chordate Cladogram
Mammals
Birds
Amphibians
Fishes
Nonvertebrate
chordates
Invertebrate ancestor
Reptiles
All chordates at sometime during their
life history have:
• a notochord: a dorsal supporting rod located
dorsally just below the nerve cord; it provides
support and is replaced by the vertebral column
in vertebrates
• a dorsal hollow nerve cord: a fluid-filled canal;
spinal cord is protected by vertebrae
• pharyngeal gill pouches: openings that
function in feeding, gas exchange, or both
Chordates that are not vertebrates
• Subphylum
Urochordata
• contains 1,250
species
Tunicates (Sea Squirts),
Larvae
• The larvae of tunicates resemble the ancestral
chordate.
• It has all three chordate characteristics and
looks like a tadpole.
• The free-swimming larva develops into a sessile,
filter-feeding adult.
Adult
• The adult has a thick-walled body sac and an
incurrent siphon and an excurrent siphon.
• Gill slits are the only chordate feature retained
by the adult form.
• In some tunicates, the adult form may have been
lost. These animals retained the larval form as
adults. Vertebrates may have evolved from
forms like these.
Subphylum Cephalochordata
Subphylum Cephalochordata
23 species of lancelets are in the genus
Branchiostoma
elongated, lance-shaped body resembles the
lancelet, a two-edged surgical knife
inhabit shallow coastal waters; they lie partly buried
in sandy substrates and filter feed
Lancelets retain the three chordate characteristics
as an adult
notochord extends from head to tail
segmented muscles and their
dorsal hollow nerve cord
Vertebrate Chordates
• Subphylum
Vertebrata
• Animals with a
vertebra column.