16. Deuterostomes Flashcards
Priapulid worms?
Similar to deuterostomes
Protostomes and deuterostomes are the two major evolutionary lineages of ….
Bilateria (split around 500 mya)
In deuterostomes…
- Heart?
- Central nervous system?
- Hard skeleton?
- Ventral heart
- Dorsal CNS
Who are the deuterostomes?
- Echinodermata
- Hemichordata
- Xenoturbellida
- Chordata
Surname of echinoderms?
Spiny skin
Habitat of echinoderms?
Marine
Example of echinoderms?
- Sea stars
- Sea urchins
- Sand dollars
Endoskeleton of echinoderms?
- Composed of CaCO3 plates
- Continuous growth (plates enlarge and new ones are added)
- Covered by thin layers of skin and muscle
Echinoderms larvae are …. symmetrical
Bilaterally (evolved from bilaterally symmetrical ancestor)
How do echinoderms change their symmetry?
Metamorphosis:
- Intermediate larval stage grows 3 adhesive arms & sucker
- Original mouth and anus disappear & new mouth reappears on left side
- Transformation from egg to newly formed starfish takes about 2 months
Water vascular system of echinoderms?
Water-filled tubes (ends in “tube feet” - podia, extend through pores in endoskeleton).
- Used for locomotion, feeding, excretion, gas exchange
- Sensory structure (chemical, tactile)
Sexual reproduction of echinoderms?
- Separate sexes
- External fertilization
- Broadcast spawning
- Larvae (planktonic, ciliated arms)
Example of Crinoidea?
Sea lilies & feather stars
Crnoidea - feeding?
filter feeders
Ophiuroidea - example?
Brittle stars - many arm spines, filter feeders, predators, detritivores
Basket stars - branched arms, filter feeders
