What are the three synapomorphic characteristics of phylum echinodermata?
- Radial symmetry in adults
- Calcareous endoskeleton (contains calcium carbonate)
- Water vascular system
What are the basic characteristics of the phylum echinodermata?
slow, sessile, marine
adults: pentaradial symmetry
larvae-bilateral symmetrical
mouth at center of arms and faces down
thin epidermis covers endoskeleton
tube feet: locomotion, feeding, detection and gas exchange
What is the class asteroidea?
sea stars
5 arms (or more)
active, walk via tube feet
predatory
use tube feet to pry open bivalves
adhesion due to glue, not suction
What is the class echinoidea?
sea urchins, sand dollars
no arms
5 rows of tube feet
slow moving
spines: locomotion and protection
eat seaweed
What is the class holothuroidea?
sea cucumbers
elongated: symmetry is secondarily bilateral, 5 rows of tube feet, some tube feet around the mouth serves as feeding tentacles
deposit or suspension feeders
shoot out internal organs if disturbed
What are the four synapomorphies of the phylum chordata?
- Notochord: cartilaginous skeletal structure, flexible rod located dorsally between the digestive tube and the nerve cord, stiff but not rigid support along body, present in all chordate embryos and some adults
- Dorsal, hollow nerve chord: unique to chordates, develops from neural plate of ectoderm, plate rolls into tube during embryonic development, nerve cord –> spinal cord and brain
- Pharyngeal clefts: located just posterior to mouth along digestive track
- Muscular, post-anal tail: most adult chordates have muscular tail posterior to anus, contains muscles and skeletal elements, reduced in many species during embryonic development
What are the seven vertebrate derived character states?
- Two or more clusters of Hox genes
- Neural crest
- Endoskeleton and pronounced cephalization
- Circulatory system modified
- Pharyngeal clefts
- Vertebral column (backbone)
- Elaborate skull (cranium)
What are the key concepts of chordates?
deuterostomes are a monophyletic group
echinodermata body plan (radial symmetry in adults, endoskeleton, and water vascular system)
ancestral chordate body plan has been retained but modified in diverse lineages
vertebrate evolution shows development of brain, and diversification of feeding methods
duplication of Hox genes led to development of complex body structures
