Phylum Chordata The Chordates!

All chordates have these 4 characteristics at some point in their lifetime: Dorsal Hollow Nerve Cord: a nerve cord that runs along the back (later becomes brain/spinal cord) Notochord: long, supporting rod that runs below the DHNC (becomes backbone/vertebral column)

Pharyngeal Slits (pouches): slits in the throat that help with gas exchange in some animals (as a fetus, humans lose these in favor of lungs) 4. Post-Anal Tail: at some point in their lives, all chordates have a tail that extends past the anus

The Generalized Structure of a Chordate Section 30-1 Muscle segments Tail Anus Pharyngeal pouches Mouth Hollow nerve cord Notochord

Chordate Cladogram Section 30-1 Mammals Birds Reptiles Amphibians Fishes Nonvertebrate chordates Invertebrate ancestor

Tunicates (sea squirts) Lancelets Most chordates are vertebrates but there are some non-vertebrate chordates. The two groups of non-vertebrate chordates (chordates without backbones) are: Tunicates (sea squirts) Filter feeders that live in the ocean Soft-bodied Show all the characteristics of chordates as LARVAE—not as adults Lancelets Small, fish-like creatures that live on the ocean floor Unlike vertebrates, their notochord (spine) extends into their head

Tunicates Take in water through incurrent (oral)siphon and releases it through excurrent (anal) siphon

SO… Phylum Chordata includes: 3 subphyla: Subphylum Urochordata (tunicates) Subphylum Cephalochordata (lancelets) Subphylum Vertebrata (vertebrates) Vertebrates: fishes, amphibians, reptiles, birds, and mammals

Vertebrates include: fishes, amphibians, reptiles, birds, and mammals All vertebrates have: A backbone Bilateral symmetry Endoskeletons Closed circulatory systems Complex brains & sensory organs Efficient respiratory systems

Introduction to Fish Jawless Fish Lamprey, Lamprey, Part 2 Hagfish