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
Asteroidea - feeding?
Predatory (fairly mobile) - evert stomach, secrete enzymes to digest prey and then engulf partially-digested prey
Crown of thorns?
- Feeds on coral polyps
- Responsible for periodic coral destruction on Great Barrier Reef
Example of Holothuroidea?
Sea cucumbers
Holothuroidea = feeding?
Detritivores, scavengers, filter-feeders
Holothuroidea - ….. relationship with pearlfish
Commensal (+/0)
Holothuroidea - skeleton?
Reduced endoskeleton
Holothuroidea - respiration?
By drawing water into anus
Chordates are …..ostomes
Deuterostomes!
……. slits are an ancestral trait of deuterostomes
Pharyngeal
3 subgroups of chordates?
- Cephalochordates
- Urochordates
- Vertebrates
What are lancelets?
Cephalochordates - adults retain all 3 chordate characteristics
Urochordate larva have which characteristics of chordate?
All 3 as larvae
As an adult, urochordates have…
Incurrent and excurrent siphons
Which has more species - deutorostomes or protostomes?
Protostomes
