Lecture 16: Intro to deuterostomes Flashcards
When did protostomes and deuterostomes split?
Cambrian
Deuterostomes
- bilaterally symmetrical
- triploblastic
- blastopore develops into an anus
- endoskeleton
What features differ in protostomes and deuterostomes?
Nervous system hard skeleton coelom anus circulatory system
Groups of deuterostomes
Echinoderms (sea stars, sea urchins)
Hemi chordates (acron worms, pterobranches)
Chordates (sea squirts, lanclets and vertebrates)
Echinoderms
benthic
only marine
bilaterally symmetrical as larvae
as adults they are pentaradial symmetrical (change via metamorphosis)
hard endoskeleton composed of CaCO3
- have water vascular system: a network of water filled canals leading to a multi-purpose extensions called tube feet that serves as gas exchange, movement and feeding system.
crinodea
echinoderm
- sea lilies and feather stars
- filter feeders
- can swim short distances
asteroidea
echinoderm
- sea stars
- fairly immobile
- have evert stomach
sea urchins and sand dollars
- have many spines used for locomotion, defence
- have pincers used for defence and cleaning
- have Aristotle lantern for scraping off algae
holothuroidea
SEA CUCOMBERS
- respire by drawing water into anus
- commensal relationship (+/0) with pearlfish
Chordates
- include vertebrates
- deuterostome
- coelomate
- bilateral symmetry
characteristic unique to chordates
- dorsal hollow nerve cord
- notocord
- post anal tail
characteristic common to chordates
- ventral heart
- reduced segmentation
- segmented musculature (generate thrusts)) called myomers
Groups of chordates
- Cephalochordates
2. Urochordates
Cephalochordates
- fish like bodies
- live in sediments
- adults retain all three unique chordate characteristics
- live in current as larvae, live in sand as adults
Urochordates
- have all three unique characteristics as larvae
- as larvae they are planktonic and/or resemble tadpoles
- as adults, they are sessile, benthic and filter feeders
