Invertebrate Diversity III The coelomate deuterostomes: Phylum Echinodermata Phylum Hemichordata Phylum Chordata Subphylum Urochordata Subphylum Cephalochordata

Q3: Deuterostomes 1)Have radial, indeterminate cleavage 2)Are ancestrally enterocoelous 3)Develop the mouth as the second gut opening 4)All of the above

Ph. Echinodermata Deuterostomes “spiny-skinned” pentamerous radial symmetry –a secondarily derived trait endoskeleton of calcium carbonate ossicles water vascular system with “tube feet”

Tube feet on a sea star

5 classes of Echinoderms Cl. Asteroidea -- sea stars Cl. Ophiuroidea -- brittle stars Cl. Echinoidea -- sea urchins, sand dollars Cl. Crinoidea -- crinoids, sea lilies Cl. Holothuroidea -- sea cucumbers

Sea star: Asteroidea Bat star

Brittle star: Ophiuroidea

Urchin: Echinoidea

Crinoids/Sea Lilies: Crinoidea

Sea cucumber: Holothuroidea Warty sea cucumber

Q2: The peculiar form of symmetry common to the Echinoderms is 1)radial 2)bilateral 3)pentaradial 4)multilateral

Q3: The major phylum most closely related to Echinodermata is our own phylum of 1)Arthropoda 2)Bryozoa 3)Ectoprocta 4)Chordata

The “Protochordates” Ph. Echinodermata Ph. Hemichordata Ph. Chordata –Subph. Urochordata –Subph. Cephalochordata –Subph. Vertebrata } Protochordates Three major deuterostome phyla:

Deuterostomes and Chordates Generic deuterostome characteristics: –Radial, indeterminate cleavage –Enterocoely –Deuterostomy The four Chordate characteristics: –Notochord –Pharyngeal gill slits –Post-anal tail –Dorsal hollow nerve chord (+ trends toward segmentation and cephalization)

Phylum Hemichordata: awkward intermediate or sideshow? Acorn worms and pterobranchs – sessile, filter-feeding, tube-dwellers Ciliated larva – similar to echinoderm pluteus Half a chordate? –Pharygeal gill slits –Stomatotochord (not really a notochord) –Dorsal solid nerve chord (but little cephalization) –No post-anal tail

Q4: The only chordate property clearly shared by the hemichordates is the 1)Notochord 2)Pharyngeal gill slits 3)Dorsal hollow nerve chord 4)Post-anal tail

Phylum Chordata: Sub-phylum Urochordata –tunicates Sub-phylum Cephalochordata –lancelets Sub-phylum Vertebrata –vertebrates

Sub-ph Urochordata: tunicates

More Tunicates

Tunicate morphology

Free-swimming Tunicate larvae

Q5: The only chordate character retained by adult tunicates is the 1)Notochord 2)Pharyngeal gill slits 3)Dorsal hollow nerve chord 4)Post-anal tail

Sub-ph Cephalochordata: lancelet

Branchiostoma -- lancelet

Anatomy of a lancelet – a prototypical chordate

Lancelet (Branchiostoma)

Q6: The closest protochordate vertebrate ancestors are the 1)Echinoderms 2)Hemichordates 3)Urochordates 4)Cephalochordates

Sub-ph. Vertebrata – a preview Central characteristics: segmented vertebral column (i.e., backbone) cranium (brain case: bone or cartilage) closed circulatory system neural crest cells – become teeth, part of cranium, adrenal glands nephritic kidneys semicircular vestibular canals seconarily schizocoelous