Porifera - Sponges Flashcards
What are the defining features of Porifera?
They are the most primitive of multicellular animals.
+ They lack organs or defined tissues.
+ Cells are multifunctional.
+ They are always sessile - once a juvenile settles it won’t move.
What is the phylum porifera?
Sponges.
How many species of porifera are there?
150 freshwater species, 5000 marine species.
At what depths do Porifera live?
Mainly shallow water, but one group is common in the deep sea.
What are their defining physical characteristics?
There is no set shape and they can be very size variable. They are often very brightly coloured.
What is the morphology of sponges?
Some species are able to bore into rock by secreting a powerful acid and eating away the rock. Others exist flat on the substratum, and others grown parallel to the substratum up into the water column. These are more common in warmer waters but can be found in temperate waters as well.
What is the pinacoderm of a sponge?
The outer surface of the sponge, made of cells called pinacocytes.
What is the inner surface of a sponge called and what is it made of?
The inner surface is mostly comprised of the choanaderm, and is composed of flagellated cells called choanacytes. This and the pinacoderm are a single cell thick.
What is the mesohyl?
The layer between the pinacoderm and the the choanoderm. It can be very thin or very thick depending on the species.
What are the three levels of body complexity in sponges?
Asconoid: flask like structure. The choanoderm is simple and continuous.
Syconoid: the choanoderm becomes more folded - which gives the sponge a greater filtering/food gathering capacity.
Leuconoid: the choanoderm becomes subdivided into separate flagellated chambers.
What are the two ‘architectural’ types of sponge?
Solid: usually leuconoid, but very variable.
Tubular: synconoid and asconoid.
What are spicules?
Calcium carbonate or silicate deposits which form ‘spines’ which help to support sponges. They are produced by sclerocytes.
What are the two types of spicules?
Microscleres or megascleres. Microscleres are small to minute and used in reinforcing (or ‘packing’) spicules. Megascleres are large structural spicules. Demosponges and hexactinellids have both, whereas calcareous sponges often only have megescleres.
What are the main sponge cell types and their functions?
+Archeocytes: large, phagocytic, used in digestion. Able to transform to other cell types. Can produce eggs but not sperm - ovarian tissue.
+Collencytes: secrete collagen. This helps bind everything together - gives the sponge cohesion.
+Sclereocytes: secrete spicules, calcium carbonate or silica.
+Spongocytes: secrete spongin, a structural protein. It creates the ‘spongy’ feelings; resilient and elastic.
+Choanocytes: flagellated cells that create currents of water in the sponge, produces sperm and some can produce eggs. They collect particles from the water current. They also flush away waste and CO2.
How do sponges pump water?
They pump water (up to 10,000 times their own volume) through the central atrium. The rate of flow is controlled by the size of the osculum & opening/closing of ostia. Water current is produced by choanocytes.
