Porifera Flashcards
Porifera features
Simple and no symmetry
Ancient and successful -650mya from rocks - may be slightly younger
No higher-level tissue organisation
Individual cells doing different things in matrix
Mostly marine (fw too)
Sessile - can move 4mm/day
Can move via other organisms - hermit crabs and dolphins
Variation in Porifera form
Can be dictated by water currents
-lots of wave action = flat and low, otherwise get damaged
Lots of food around will be smaller
Deeper with little currents and food will be larger - need as much water through as possible
Venus’s flower basket
Has spicules made of silicate - 75% syncytial tissues - no boundaries in cells
Forms fine and delicate patterns, but are rigid and strong
If tissue stimulated - stop beating flagella of choanocytes
But don’t have a NS…
Electrical impulses can travel in syncytial tissue
Spong feeding
Take organic material from water
Food trapped in choanocytes and engulfed by amoebocytes which are totipotent, also clean outside of sponge
Digestion intracellular
Bigger sponges need more choanocytes for current in organism
How do they help coral reefs?
Coral reefs in water nutrient poor in P and N
Sponges important in generating these
Take up C from water, when bits of sponge fall off is eaten by other organisms
Deposit C back into form that can be used by others
Carnivorous Porifera?
Those in the deep sea
Have modified spicules into sticky pads used for capturing prey
Grow around prey and break it down
Sponge regeneration
Have amazing powers of regeneration
Wilson put sponge through sieve - sponge reformed
Put two different sponges through together resulting in reforming two separate sponges
-level of immunorecognition
Asexual reproduction in Porifera
By budding - little parts of itself drop off and regenerate into an individual
By gemmules when conditions aren’t favourable (seen in FW forms, where ponds may dry out etc.)
When conditions get better, amoebocyte comes out of sponge and reforms new one
Sexual reproduction in Porifera
Usually hermaphrodites
Release at different times - triggered by temp, photoperiod etc.
Sperm expelled out of osculum and into another sponge
Sperm taken up by choanocyte trapping and engulfing it moving it to the eggs
Larvae retained for a period of time till blastula stage
Protection
Don’t move = vulnerable
Brightly coloured by algae or because they are toxic
Warning signals to get rid of competitors
Produce biotoxins
Also have antibacterial properties to fend off bacteria
Causes dead zones in corals if living with them
