lec 6 Flashcards
phylum porifera species richness marine and freshwater
freshwater 200 species
marine 9000
phylum Porifera vs rest of metazoa
-show least cellular differentiation and integration of all metazoa
-lack cross striated ciliary rootlets
-almost all sponge adults are sessile
what symmetry do sponges have
no clear axes of symmetry
Ponifera water canal system components
ostia
oscula or osculum
spongeocoel
ostia
one or a few large incurrent pores
oscula, osculum
few or one large excurrent pores
spongocoel
spacious water filled central cavity
nota true coelom
chonanocytes
flagellated cells that water flows through
non cellular filler material
mesohyl
internal skeleton of ponifera
made of calcareous or silicious spicules or collagenous spongin( or both)
cells relatively autonomous and show
totipotency or pluripotency
totipency and pluripotency
capacity to transport into all (totipotency) or most cell types (pluripotency)
what are the two major growth forms of sponges
upright and encrusting
3 body plans in sponges
ascon
sycon
leucon
ascon type
single flagellated pumping cavity(spongocoel)
sycon type
many flagellated canals connected to spongocoel
leucon type
many flagellated chambers connected by non flagellated canals
all 3 body plans occur in class
calcarea
flat cells that form outer body covering
pinacocytes
pinacocytes form the
pinacoderm
some sponge species, pinacoderm acts like
true’
epithelial tissue
archaeocytes
what are they also known as
amoeboid cells that
can transform into any cell type (totipotent)
amoebocytes
encircle osculum and
flagellated chambers, can open and close oscula
myocytes
tubular cells
porocytes
choanocytes
(collar cells) in
choanocyte layer
punnping and feeding, can transform to sperm
hexactinellids unique features
main part of their body becomes syncytial
syncytium
-fused multinucleate mass of cystoplasm in common cell membrane
-allows electrical signals to travel
-analogous to nervous system of other animals
skeletal support in sponges
-collagen fibres:
are either loosely dispersed in the mesohyl
-spongin: sturdy network of large strands
-spicules
spongin skeletons occur only in some
what sponges only have spongin in they skeleton
demospongiae
bath sponges
what do spicules consist of?
calcium carbonate or silicon
Monorhaphis chuni
very long spicule running through centre of its body
feeding in sponges
-the choanocytes capture food like choanoflagellates
-phagocytized
-capture very tiny particles
-they form mutualisms or can be predatory
what happens w sponge mutualism
-many sponges harbour photosynthetic
endosymbionts
-sponge privide nitrogen symbionts provide carrbohydrates
sponge sneezing
-special non-mobile cilia on
osculum lining sense when the water flow is reduced
-myocytes contract and “sneeze” water and blockage out
what happens if osculum removed?
no sneeze, why it is thought as analogous to sense organ
how do most sponges reproduce?
they are sequentially hermaphroditic
-either protandry or protogyny
protogyny
female first and then male
protandry
male first and female later
lecithotrophy
larva swims only briefly before settlement, getting all the
food it needs from its yolk supply
brooding species
-fertulizatiin internal in the female sponge
-larvae are brooded in the female until they to swim via cilia or flagella
broadcast spawning species fertilization
occurs in
the water
sexual reproduction in sponges
andwhat transforms to the sperm and eggs
-choanocytes transform into
sperm (collar dropped) and eggs
-sometimes eggs and sperms released broadcast spawning or free spawning
-sometimes eggs retained and sperm broadcasted
how many different types of embryogenesis
many
however, at
least briefly, more than
one layer of cells is
present
do sponges reproduce asexually
most species also
have asexual
reproduction
-budding
and/or fragmentation
Repair and recognition in Porifera
-certain sponges are able to
reconstitute their bodies after cells are separated
-cell-cell recognition theory inspired
Freshwater sponges unique features
special resistant
structures called gemmules that can
withstand freezing and drought
Economic uses for sponges
-bath sponge industry
-bioprospecting for pharmaceutical chemicals because of their antimicrobial, antiviral chemical defences
Jurassic Period glass sponges
glass sponge reefs were once
thought to have disappeared
class calcarea
the calcareous sponges
Class Hexactinellida
glass sponges
Class Demospongiae
most species-rich
only class that includes freshwater spp.
Class Homoscleromorpha common name
no common name
Calcarea
skeleton structure
calcareous spicules with 3 rays, no spongin
Demospongiae skeleton structure
-: silica spicules never 6-
rayed, some have spongin + spicules and some only spongin
Hexactinellida: skele structure
silica spicules, with 3 or 6 rays, no spongin
Homoscleromorpha skeleton structure
: small silica spicules called calthrops
that have 4 rays, no spongin
