Metazoans Flashcards
What are Metazoans?
Multicellular animals
What fossil record do metazoans dominate?
Phanerozoic (Cambrian to present)
What does multicellularity allow for?
Specialisation of cells
What are some examples of cell specialisation?
Locomotion
Respiration
Reproduction
Nutrient acquisition (feeding)
What 2 ways can metazoans be separated by embryo?
Spiralians
Radialians
What are spiralinas?
cells spiral within embryo
What are some examples of animals with Spiralians?
Molluscs and Arthropods
What are some examples of organisms with radialians embryos?
Cnidarians
Brachiopods
Bryozoans
Echinoderms
Hemichordates
What are the vast amount of metazoans?
protostomes
How are protostomes different from Deuterostomes?
Protostomes mouth develops first deuterostomes anus develops first
What are the sister groups to metazoans?
Fungi and Choanoflagellata
When are metazoans first thought to have been present?
At the base of the Cambrian but Ediacaran life has meant maybe pre-Cambrian
What are phylum porifera?
sponges
What are sponges like?
Very simplistic although some articulated specimens might have spicules made of biogenic silicon
What do sponges do?
Filter water for nutrients
What are Stromatoporoids?
sponges produced by calcium carbonate instead of silica which are now extinct but were common reef builders in Palaeozoic
What is an example of where stromatoporoids can be found?
Wren’s nest
What is included under the group Cnidarians?
Jellyfish
Sea anemones
Corals
What is the complexity of Cnidarians like?
simplest of common true metazoans (besides sponges) - few distinct tissues in radial plan
What is the mode of life for sea anemones and corals?
Attached (sessile)
What is the mode of life for jellyfish?
Free swimming (pelagic)
What is the cycle of mode of life for Cnidarians?
Jellyfish can be attached to polyp and then placed into water column but can then potentially sink back don becoming attached
What are Zoantharian corals?
hard corals- largely mineralised (have the best fossil record)
What is the epitheca of Cnidarians?
The outer wall
What is the mesentries of Cnidarians?
in polyp (fold like tissue) secrete septa (struts)
How are mesentries best seen?
horizontal sections
What are tabulae?
horizontal sheets in the corallite
What are dissepiments?
small curved sheets commonly close to epitheca (bubble warp to outer wall)
What are rugose corals composed of?
CALCITIC
What is the septal insertion of rugose corals?
Serial insertion
What is the process of serial insertion of septa for rugose corals?
Protoseptum
Cardinal and counter cardinal
Buttressed by alar
Counter lateral
What is the septal insertion of Sclerantinian corals?
Cyclic
When were Kilbuchophyllia present?
Mid-Ordovician
What are Kilbuchphyllia an example of?
Iterative evolution
What is iterative evolution?
When the same/ similar morphologies appear through evolution
What are Kilbuchophyllia similar to?
septal insertion and microstructure identical to scleractinians
What wiped out the evolutionary experiment which was Kilbuchophyllia?
located in one locality in scotland on the side of a volcano prone to landslip which is thought to have wiped them out
What does Kilbuchophyllia demonstrate?
potential for the mineralisation of other soft bodied anemones
What are all living zoantharian?
scleractinian
How can scleractinians be ecologically divided?
hermatypic zooxanthellate
ahermatypic azooxanthellate
What are ahermatypic azooxanthellate?
don’t have symbiotic algae
What are hermatypic zooxanthellate?
have symbiotic photosynthesizing algae within inner cell layer
What conditions are needed by hermatypic zooxanthellate?
Photic zone- shallow water (>50m)
Minimum water temperature 18 deg C
Normal marine salinity
Firm non-muddy substrate
What conditions are needed by ahermatypic azooxanthellate corals
Common up to 500 m (extend to 6000 m)
Tolerate cold waters (0 deg C)
Most do not build reef-like structures
but some do
What is a location where ahermatypic azooxanthellate are found?
Darwin Mounds: glass sponge Aphrocallistes and cold water coral Lophelia (affected by trawling and gas exploration)
What is a coral reef?
presence of a framework structure is rigid and wave resistant (hermatypic zooxanthellate)
What are bioherms?
formed below wave base ahermatypic azooxanthellate
What is growth rate controlled by in modern coral reefs for hermatypic zooxanthellate?
Growth Rate and Form vary depending on light and water depth
What did Palaeozoic coral growth rate vary based on?
Growth Rate and Form typically vary
depending on substrate and sedimentation
How should genus and species be represented with an example?
Genus first letter capital
, species in italics
Domestic cat= Felis catus (italics)
What is a species when applying it to corals?
a taxonomic division that generally refers to a group of organisms which are similar in structure
What is an example of a fasciculate coral?
Phaceloid - corallites infilled by matric
