Bilaterians Flashcards
Where did trace fossils first come from?
Animals going 3D- mixing sediments- burrowing- swimming- chasing
When did transition from 2D ‘biomat world’ to 3D world occur?
Cambrian start
3 clades of bilateria?
Lophotrocozoa, Ecdysozoa, Deuterostoma
What phyla included in Deuterostomia?
Echonoderms, Hemichordates and Chordates
What do deuterstomia have in common?
Deuterostomy and radial cleavage (these arent unique character)
What are the 5 classes of Echinoderms?
Asteroids (starfish); ophiuroids (brittle stars); Echinoids (sea urchins); holothurians (sea cucumbers); crinoids (sealilies + feather stars)
What is pentaradial symmetry?
5 fold
4 important features of Echinoderms
pentaradial symmetry, water vascular system, endoskeleton, marine
What symmetry do starfish and brittlestars have?
Bilateral- conserved from bilaterian ancestor?
How do starfish feed?
Gut extends down arms. Part of stomach extruded inside out into shell of prey, digestive juices released, can eat!
What is a use of the water-vascular system in Echinoderms?
Locomotion
Feature of Ophiuroids (brittle star)?
Thinner and bendier = for detritus feeding + NO ANUS
What is between Echinoids ossicle pines (which are covered in living tissue)?
Pedicellaria- chop up larvae that land- like little teeth
What do Holothurians (sea cucumber) do when attacked?
Eject Cuvierian tubules. If that doesn’t work.. .. then eject intestine!
What are the 2 classes of Hemichordates?
Enteropneusts (acorn worms) and Pterobranchs
How do Enteropneusts (acorn worms from Hemichordata) feed?
Pharyngeal slits- holes on side of body and cilia to make water current
+ filter feeds
Name 6 features of a generalised chordate
Pharyngeal slits; endostyle; dorsal hollow nerve chord; postanal tail; notochord; lateral muscles
Function of Pharyngeal slits in chordates?
Feeding and gas exchange
Function of endostyle in chordates?
Internal secretory structure of mucus - goes over pharyngeal slits
what germ layer is doral hollow nerve chord derived from in chordates?
ectoderm cells
Function of notochord in chordates?
Important for locomotion = skeletal structure down center of animal
What are the 3 subphyla of the phylum chordata?
Tunicates (urochordates); cephalochordates (amphioxus); vertebrates
What are the 3 groups within Tunicates?
Ascidiacaea (sea squirts); Larvacea; Thalacea
What does sessile mean?
Immobile
What is name for thick cellulose coat found on Ascidians?
Tunic
Where did genes for tunic of Ascidians (sea squirts) come from?
Horizontal gene transfer (from bacteria)
What do larvacea look like?
Sexually mature tadpoles in jelly houses
What do Thaliacea look like?
Sea quirts- but they can SWIM
What are 2 major changes in amphioxus (cephalochordata) body plans?
Notochord extends past brain for stiff tip for burrowing.
Pharyngeal slits no longer interact with outside world as water goes in atrial cavity and out atrial pore
What are the 3 clades of bilaterina?
Lophotrochozoa, ecysozoa and deutrostomia
What phyla are included in Ecdysozoa?
2x wormy; nematodes and nematomorphs
3x leggy; tardigrades onychophora and arthropods
What do ecdysozoa have in common?
They moult (ecdysis)