Quiz 2 - Deuterstomes Flashcards
What is the earliest fossil of exhinoderms and deuterstomes found in the ediacaran
Arkarua
What dominated the ediacaran fauna? What about the cambrian?
Sponges and diploblasts
Cambrian - arthropods
What is the first accepted deuterstome fossil
Vetulicolians
- segmentation, bipartite, gill slits
Homalozoans were early deuters .. in the mid cambrian and devonian - they had…
Gill slits, post anal tail, lacked radial symmetry
What were the deuterstomes close to hemichordates with a bipartite body, and segmented tail?
Velulocystida
What were similar to the velulocystids (close to hemichordates)?
Stylophorans
What were the two interpretations of early echinoderms
Enchino w early feeding arm
Or
Echino pre-radial w hemichordate stalk
The yanjiahella was found between the….
Echino and hemichordate
What was the earliest accepted hemichordate from the lower cambrian
Yunnanozoon
What was the fossil with a notochord and segmented musculature?
Pikaia
What was the chordate fossil that lacked a cranium?
Haikouella
What belongs to the ambulacraria?
Echinoderm
Hemichordate
What phyla of ambulacraria are exclusively marine, benthic, macroscopic?
Echinoderms
What is different between the forms of paleozoic echinos and modern echinos?
Paleo - sessile
Modern - motile
What is the most ancient class of echinos
Crinoidea
Sea lillies and sea feathers
Describe the sea lillies and sea feathers… what class? Where are they found? How to they use their tube feet?
Crinoidea - ancient class
All benthic
Tube feed for suspension feeding
What class do sea stars belong to
Asteroidea
What is benthic, found at all depths, pentaradial, predatory and scavenger?
Asteroidea - sea stars
What class do brittle stars belong to?
Ophiuroidea
What species are found in class echinoidea?
Sea urchins and sand dollars
For sea urchins and sand $, what gives them their pentaradial symmetry
Fused skeletal ossicles
What is the regular form of echinoidieans?
Sea urchins
Long movable spines
Move w tube feet + spines
Pedicellariae for cleaning and defense
What is the irregular form of echinoidieans?
Sand $ form
Short spines for locomotion + free sediment, secondary bilateral symmetry for digging and burrowing
What class are sea cucumbers in?
Holothuroidea
How did sea cucumbers get bilateral symmetry
Secondarily
How to cucumbers eat
Suspension feed / deposit feed using tentacles + mucus
How to cucumbers move?
Ventral tube feet + body muscles
What are hemichordate
Marine
Benthic
Macroscopic
Motile or sessile
What are the 5 classes of sea stars
Crinoidea (sea lillies + feathers) Asteroidea (sea star) Ophiuroidea (brittle) Echinoidea (urchins + sand $) Holothuroidea (cucumbers)
What are the two classes of hemichordates?
Pterobramchia
Enteropneusta (acorn worms)
Describe pterobranchia
Tube dwelling colonial animals
Looks like bryozoans, superficially
Tripartite body
Describe enteropneusta
Acorn worms
Solitary, sediment dwelling
Tripartite
Feed on sediment particles
What are the characteristics of ambulacraria
Tripartite bodies (and coeloms)
Axial complexity
Larval forms free swimming, bilateral, soft bodied, ciliated
What surrounds the viscera (internal, organs) and contains the watery coelomic fluid
(Ambulacraria)
Pervisceral coelom
All ambulacraria classes have lost this except for the crinoids.. what is it
Hydrocoel
What makes the WVS in ambulacraria
Isolated portion of coelom
Hemichordate have a proboscis, stalk and collar… what is the protocoel?
Space insider proboscis mostly muscles fibers
What is the difference in axial complexity in echinoderms and hemichordates?
Echinos - junction of perivisceral coelom, WVS, + hemal coelom
Hemichordates - heart kidney complex
What are the 6 characteristics of echinoderms
Endoskeleton Pedicellariae (pincers) Dermal branchiae / papulae WVS pentaradial symmetry Ambulacra grooves
What is the endo skeleton of enchinoderms made up of?
Skeletal ossicles
Calcium carbonate makes the stereom
How does the endo skeleton of holothuroidea differ from other echinos?
Lost bulky plates, but have microscopic plates instead
Describe what the pedicellariae do in enchinos
Dorsal side
3-forceps like extensions, cut off larvae / pinch
Looks like long stalk w bulbous head w 3 valves
The pedicellariae are found where
Base of spine
What do the 3 valves of pedicellariae do?
Act like jaws that snap at anything the touches their sensor
What is the dermal branchiae
Thin folds of body wall
Extend btw ossicles
Used for gas exchange
What is the function of papulae / dermal branchiae
Gas exchange/ respiration
Thought of like gills on the skin of echinos - thin fold of the body wall, extend btw ossicles
The WVS of echinos extends from the body surface as a series of tentacles projecting… what are these projections / extensions
Tube feet / podia
What were tube feet originally evolved for?
Feeding first, then locomotion
How do the tube connect to the outside?
Via the madreporite
What is the function of polian vessicles?
Maintain internal pressure
The radial canals extend down what…
Down the ambulacral grooves
Where to lateral canals lead to?
Tube feet
How to tube feet extend from the echino?
Hydrostatic pressure via ampullae
Ampullae move water into tube feet
List the different parts of echino WVS
Podia / tube feet
Connects to the outside via madreporite
Polian vessicle - internal pressure
Radial/ring canals - extend down ambulacra
Lateral canals - lead to tube feet
Ampullae - pull water into tube feet
Tube feet extend via hydrostatic pressure
What is pentaradial symmetry in echinoderm linked to?
Sessile lifestyle of ancestor
What is different about the symmetry of sea urchins and sand dollars (Ophiuroidea)
Superimposed bilateral symmetry on pentaradial symmetry
How is pentaradial symmetry developped in echinos upon metamorphosis
Metamorphosis of echinos makes larva
The left side of larva develops into adult + makes oral side
Right side is absorbed
How to asteroideans develop the WVS + canals
Coelom cavity makes a U shape
Coelomic parts separate
Form WVS + canals
How do echinos develop
What are the 2 larval stages
1 - ciliated bands cover bipinnarial function in locomotion + feeding
2 - brachiolaria
Larva grows 3 adhesive arms + sucks to attach to surfaces
Larva then metamorphosis
What classes have ambulcra grooves restricted to the oral surface
Crinoids
Asteroidea
Ophiuroidea
What classes have ambulcra grooves that extend oral to aboral, and lack arms
Echinoidea
Holothuiroidea
What did echinos likely descend from?
Bilateral ancestors that evolved radially for a sessile lifestyle
What fossils lacks 5 fold symmetry but has spiral grooves indicative of ambulacral groove
Heliocoplacus
What extinct class of echinos was sessile with thick stalk + plates that had pentaradial symmetry
Edrioasteroidea
What were the oldest group of echinos that had starfish and brittle star characters
Asterozoans
What was the hemichordate fossil that looked like tiny saw blades with tubes similar to pterobranchia
Grapolithina (extinct)
What are some characteristics of hemichordates similar to chordates
Branchial opening (gill slits) that open into the pharynx
Stomochord
Dorsal nerve chord + smaller ventral nerve chords
Tripartite body
