Phylum Porifera (Parazoa) Flashcards
Habitat of porifera
mostly marine, with some freshwater
how do porifera feed
active filtering
size of porifera
less than 2 meters
what do porifera lack
organs, sensory systems, tissues
when do the porifera fossils date back to
early cambrien period
Basic body plan of sponges
- built to create a water current through the body to filter food
- mass of cells embedded in gelatinous mesophyll
- pinacocytes: skin cells
- Choanocytes: filtering collar cells
- Archaeocytes: ameboid
- water flow driven by flagella choanocytes
3 levels of complexity of sponges
- asconoid
- synconoid
- leuconoid
what 2 sponges are radially symmetrical and which one is asymmetrical
- ascanoid
- syncanoid
asymmetrical
1. leucanoid
what is the sponge skeleton made of
collagen fibrils and spicules
What do leuconoid secrete
a form of collagen traditionally know as spongin
what are spicules made of
silica or calcium carbonate
what are choanocytes
Flagellated collar cells
• Lines canals and filter chambers
• Structurally and genetically similar to choanoflagellate protozoans
what are pinacocytes
• Epithelial like cells on exterior surfaces, some are contractile
what are archeocytes
amoeboid cells in the mesophyll which
- ingest food
- differentiate into other cell types
Function of sclerocytes
secrete spicules
function of spongocytes
secrete spongin
collencytes
secrete collagen
what type of digestion do sponges possess
intracellular
how is food phagocytized
by
- archeocytes
- choanocytes
- pinacocytes
- pinocytosis
- direct absorption
how do sponges handle respiration and excretion
via diffusion
2 types of asexual reproduction for sponges
Bud formation
Fragmentation followed by regeneration
what are the 2 types of bud formation in sponges
- external buds
2. Gemmules
what is the function of a gemmule
- its a resistant life stage with a protective covering
2. survive adverse conditions
sexual reproduction term used for sponges
monecious meaning having both male and female reproductive cells in the same body
what type of sexual reproduction do sponges use
broadcast fertilization
1. take in sperm from exterior and fertilize internally
what do sponge zygotes hatch into
swimming parenchymula larva which swim and settle else where
what is sexual reproduction inversion
A hollow blastula forms then inverts to become amphiblastula
3 classes of sponges
o calcarea
o hexactinellida
o demospongiae (most abundant)
description of class Demospongiae
o Siliceous spicules, or sponging
o Includes the only family of freshwater sponges
o Very diverse yet only leuconoid canal system found in this class
description of class calcarea
o calcareous spicules
o includes species with asconoid, syconoid, and leuconoid canal systems
o only extant class with the asconoid canal system
description of class hexactinellida
o Structurally very different from other 2 classes
o 6 rigid siliceous spicules fused into rigid structure (glassy looking)
o body consists of continuous syncytial tissue
