Porifera and Diploblasts- Biodiverity
What are Porifera
These are sponges so have no true symmetry
There is no true tissue but different cell types
There are No Hox Genes and reproduction take place via Sequential Hermaphroditism
How do Porifera feed
They are suspension feeders so gain food that is carried in suspension in water that get
What are sponges made of
There are some sponges that have sharp spicules made of calcium carbonate or silica ajd others that are more flexible due to fibres are made of protein called Spongin
What are diploblasts
These are animals that have 2 tissue layers made in gastrulation
Triploblasts have 3 layers and sponges have no tissue layers at all
The diploblasts have 2 phylum in what are they
There are Cnidaria which are Jelly Fish, Sea Anemones, Corals
There are also Ctenophora which are comb jellies
These phylum are both mostly marine based animals
What is Gastrulation
This is where single layered blastula turn into a double layered gastrula to then allow true tissues to develop
The Diploblasts are basal meaning that they split from the tree earlier than other animals but are still as evolved so are not primitive animals
How did early diploblast evolve
A Blastula like animal settle on sea floor and then it will invgainate to increase the feeding efficiency
The end results diploblastiic protoanimal
What are Cnidaria
These are very old based on the fossil record and are all diploblasts
Made up of Jelly Fish, Sea Anenomes, Corals
What is the Body form of the Cnidaria
The sessile species and the meduse species all have radial symmetry
They all have 2 tissue layers being the gastrodermis and epidermis
The mouth and anus are in the same place and they both have tentacles
What is the circulatory system of the Cnidaria
There is no proper body cavity and only the mesoglea between the 2 tissue layers
There is circulatory system by the use of water filled coelenteron that is enclosed by the gastrodermis
How do Cnidaria Locomote
Medusa move by swimming via jet propulsion, caused by the cornal muscle relaxing to allow the subumrellar cavity to expand and fill with water
Then in the left subumbrellar cavity contracts due to the muscles contracst forcing the water into a jet to swim
Hydra swim by a sumersaulting mechanism
What are Nerve Nets - Polyps
They allow multidirectional diffuse impules
They have sensory, motor neurones and interneurones
Have a nerve net at the base of the epidermis and gastrodermis connecte by interneurones to then mesoglea
What is the medusa nerve net
The same as in Polyps but there is an additonal nerve ring
As well as marginal ganglia at the circumfernace to receive inputs from sensory organs to act as a pacemaker for swimming muscles
How do Cnidaria reproduce
Via asexual reproduction so cloning is common in polyps but also happne in medusa
How do Jelly Fish sting you
They have a cnidocyte containing an Nematocyst with a stored inverted thread
On tactile or chemical cue to cause stimulation the thread is released and puncture the prey leading to the injection of posion to the prey
How are Cnidaria Classified
Hydrozoa
Schyphozoa
Cubozoa
Anthozoa
What are the Hydrozoa
These are Portugese Man of War
They are all marine and have both polyp and mdeulla stage
The Polyp stage is often in colonies
What is the Sail in hydrozoas
A gas filled air sack that is equipped with a siphon to allow the quick defaltion in case of defence so they then submerge
They have 3 lateral polyp type:
Dactylozoid for defence and catch prey
Gonozooid for reproduction
Gastrozooid for Feeding
What ar Scyphozoa
These are true Jelly fish with over 200 species globally
They are marine all of them and free swimming when in medusa stage but reduced in polyp stage
What are Cubozoa
These are Box jelly fish with 26 species known
Have extreme deadly poison
They are actove predators and hunt fish
Have eyes with cornea, retina and lens to form an image but no brain so have complex eyes
All marine
What are Anthozoa
Largest class with 6000 species
Usually Sea Aenomes and corals
No medusa stage only phylp
All marine and all are sessile
What are Ctenophora
The other extant group of diploblasts such as Comb Jellies
How do Ctenophora move and anatomy
They have rows of fused cilia that form a comb for locomotion
They have comb plates, tentacles, Mouth with a Pharnyx and a working stomach with gut divison
Have mouth and anal pores seperate
What are comb jellies n
These are Ctenophora with around 100 species
Never sessile or colonial
Adhesive cells called colloblast on the 2 tentacles foir catching prey