Porifera Flashcards
what is porifera?
sponges
what are phylogenetic trees used for?
understanding how things evolved
what are chanoflagellates?
single cell protists
sister group to animals
can aggregate into multicellular forms
key features of porifera?
sessile filter feeders - unique canal system which uses water currents low and encrusting/ erect branching no organs or true tissues - no CNS long fossil record lack obvious symmetry
ecology of porifera?
marine and all depths
larvae free swimming, adults sessile
environment strongly affects size and shape
rarely predated - smelly, sharp, distasteful
good habitats for other organisms
function of water canal system?
uses pores
connected by canals with flagellated choanocytes which generate current and trap food
oscula - out
ostia - in
three types - asconoid, syconoid, leuconoid
cell types in porifera?
choanocytes - generate water current and trap food - collar of microvilli, flagellated, one end embedded in mesophyl
mesophyl - skeletal elements
archaeocytes - phagocytose food particles, differentiate into other cell types
pinacocytes - external epithelium
physiology of porifera?
non-selective filter feeding
digestion intracellular - phagocytosis
respire/excrete by diffusion
development of porifera?
monoecious - male and female sex cells
sex cells formed by transformation
flagellated cells internalised on settlement - become choanocytes
asexual budding - withstand unfavorable conditions
dissociation - association: can regenerate and recognise themselves/each other
what are spicules?
the skeleton ish - made up of silicon, calcium carbonate or spongin
features of calcarea?
CaCO3 spicules
1,3 or 4 rayed w/ superficial radial symmetry
features of hexactinellida?
glass sponges silicon spicules 3-axon or 6-rayed vase or tube shaped deep water
features of demospongiae?
silicon spicules
spongin skeleton - collangeous
some have solid catalytic skeleton
features of homoscleromorpha?
absent rigid skeleton
occasionally present - kinked oxeas
